The Power of When: Discover Your Chronotype–and the Best Time to Eat Lunch, Ask for a Raise, Have Sex, Write a Novel, Take Your Meds, and More by Michael Breus and Mehmet C. Oz
This precisely engineered timekeeper is called your circadian pacemaker, or biological clock. Specifically, it’s a group of nerves called the suprachiasmatic nucleus (SCN), in the hypothalamus, right above the pituitary gland.
It takes a day for the body to adjust to a one-hour time zone difference, and, on horseback or in a coach, it’d take about that long to go that far. Starting in the mid-twentieth century, in the blink of an eye, evolutionarily speaking, we could travel multiple time zones in a few hours, leaving bio-time lagging behind.
It took only 125 years to undo 50,000 years of perfect bio-timekeeping. Saying that our physiology hasn’t evolved as quickly as our technology is the understatement of the millennium. As a result, our “when” is way, way off.
(check out Lighting Science, http://www.lighting.science)
Treating a disease such as cancer on bio-time can save your life. In 2009, researchers from the University of North Carolina School of Medicine experimented with mice to determine if timing of medication affected the speed of DNA repair to damaged cells. They took extracts of the mouse brains at various times and found that when medication was taken at night, DNA repaired itself seven times faster, in correspondence with the circadian rising and falling levels of a certain enzyme. The researchers theorized that, to minimize side effects and maximize effectiveness, chemo drugs should be given to patients when their
cells are better able to repair themselves.
Thinking on bio-time can make you smarter and more creative. In 2011, a team of psychologists from Michigan State University and Albion College asked their study subjects to solve problems, some analytical and some that required insight, at different times throughout the day. The subjects solved creative problems better during their non-optimal times, when they were tired and groggy. They solved analytical problems at their optimal times, when they were wide-awake and alert. The researchers concluded that creative and analytical thinking operates on bio-time. If you set out to solve a certain type of problem, you’ll do better at certain times.
gene function. Which group lost more weight? The early eaters lost twenty-two pounds, on average; the late eaters lost, on average, seventeen pounds, a 25 percent difference.
Living on bio-time can make you happier. In 2015, researchers at Copenhagen University Hospital, in Denmark, treated seventy-five patients with major depression through the use of either daily chronotherapy (bright light exposure and a consistent wake time) or exercise. Sixty-two percent of the chronotherapy patients went into remission in six months. Only 38 percent of the exercisers did.
The number of hours between a runner’s wake time and race time had a huge impact on performance. If the late risers ran in the evening, they were much faster than if they ran in the morning, for example. The differences in speed were significant, measuring up to 26 percent.
Your sleep drive is genetic, and it determines how much sleep you need and your depth of sleep. Those with low sleep drive don’t need a lot of sleep, so the night seems very long to them. Low sleep drive people are easily woken up by sound and light disturbance, and they wake up feeling less than refreshed. Those with high sleep drive need more hours of sleep, so the night feels too short for them. High sleep drive people sleep deeply, but they wake up feeling less than refreshed no matter how much sleep they get. Those with medium sleep drive sleep somewhat deeply and are satisfied and refreshed by seven hours of continuous rest.
1. Dolphins. Real dolphins sleep with only half of their brain at a time (which is why they’re called unihemispheric sleepers). The other half is awake and alert, concentrating on swimming and looking for predators. This name fits insomniacs well: intelligent, neurotic light sleepers with a low sleep drive. 2. Lions. Real lions are morning hunters at the top of the food chain. This name fits morning-oriented driven optimists with a medium sleep drive. 3. Bears. Real bears are go-with-the-flow ramblers, good sleepers, and anytime hunters. This name fits fun-loving, outgoing people who prefer a solar-based schedule and have a high sleep drive. 4. Wolves. Real wolves are nocturnal hunters. This name fits night-oriented creative extroverts with a medium sleep drive.
Remember, your chronotype is genetic—determined specifically by the PER3 gene. If you have a long PER3 gene, you need at least seven hours of deep sleep to function, and tend to be an early riser. If you have a short PER3, you can get by on light or little sleep, and you tend to be a late riser. It’s likely that at least one of your parents had the same chronotype as you.
Dolphins account for 10 percent of the population. Light sleepers, they rouse at the smallest noise to wake and warn the group of danger. • Lions account for 15 to 20 percent. They rise early, taking the morning shift of guarding the group and watching out for roving predators. • Bears account for 50 percent. Their cycles match the rise and fall of the sun; they hunt and gather in daylight. • Wolves account for 15 to 20 percent. They take the late shift to guard the group, drifting off when the most extreme Lions start to stir.
DOLPHIN • Four Key Personality Traits: Cautiousness, introversion, neuroticism, intelligence • Four Key Behaviors: Avoiding risky situations, striving for perfection, obsessive-compulsive tendencies, fixating on details • Sleep/Alertness Pattern: Dolphins usually wake up feeling unrefreshed and are tired until late in the evening, when they suddenly hit their stride. Most alert: late at night. Most productive: in spurts throughout the day. Naps: They try to nap to catch up on sleep but can’t quite make it happen.
LION • Four Key Personality Traits: Conscientiousness, stability, practicality, optimism • Four Key Behaviors: Overachieving, prioritizing health and fitness, seeking positive interactions, strategizing • Sleep/Alertness Pattern: Lions wake up bright-eyed at dawn or earlier, start to feel tired in the late afternoon, and fall asleep easily. Most alert: noon. Most productive: morning. Naps: Lions hardly ever nap. They’d rather be doing something useful.
BEAR • Four Key Personality Traits: Cautiousness, extroversion, friendly and easy to talk to, open-minded • Four Key Behaviors: Avoiding conflict, aspiring to be healthy, prioritizing happiness, taking comfort in the familiar • Sleep/Alertness Pattern: Bears wake up in a daze after hitting the snooze button once or twice, start to feel tired by mid-to late evening, and sleep deeply but not as long as they’d like. Most alert: mid-morning into early afternoon. Most productive: late morning. Naps: Bears catch extra hours on the weekends, on the couch.
WOLF • Four Key Personality Traits: Impulsivity, pessimism, creativity, moodiness • Four Key Behaviors: Taking risks, prioritizing pleasure, seeking novelty, reacting with emotional intensity • Sleep/Alertness Pattern: Wolves have difficulty waking up before 9:00 a.m. (they do it, but they’re not happy about it), are groggy until midday, and don’t feel tired until midnight or later. Most alert: 7:00 p.m. Most productive: late morning and late evening. Naps: Tempting, but if a Wolf sleeps during the day, he won’t fall asleep at night. It’s just not worth it.
To take the Temperature Test, record your temperature every hour between 5:00 p.m. and bedtime. When does your temperature start to rise? When does it start to drop? The rise in temperature won’t be dramatic. It could be just a few tenths of a degree (this is where digital thermometers come in). Chart your temperature for three days to collect sufficient data.
Dolphins tend to be neurotic and private. But once the intimacy wall is breached and all of their quirks come out, they can form extremely close, loyal relationships.
But for Dolphins, cortisol levels are elevated at night.
Researchers at the University of Goettingen, Germany, tested2 the plasma cortisol secretions of seven severe insomniacs over the course of the entire night.
At wake time, cortisol production in Lions, Bears, and Wolves goes up to get them moving. But in Dolphins? Their cortisol levels are at their lowest in the morning. Researchers at the University of Luebeck, Germany, tested3 the salivary cortisol in fourteen insomniacs and fifteen healthy, normal sleepers. The insomniacs’ morning cortisol levels were significantly lower than were those of the control group. The lower their salivary cortisol, the lower their self-reported sleep quality.
In a 2015 Mayo Clinic study, sleep-deprived subjects’ systolic and diastolic blood pressure markers rose at bedtime. The numbers didn’t go down when subjects were sleeping, which, as you can well imagine, negatively affected the quality of their sleep.
In contrast, the brain’s wandering-mind regions light up when a Dolphin is sleeping. Dolphins’ night dreams are more like daydreams.
• Increase energy in the early hours to make better use of morning hours. • Decrease anxiety in the evening for a more restful night.
Unrealistic expectations. Insomniacs need to lose the illusion that if they could get eight hours a night, all of their problems would go away.
Inconsistency. The power of when comes into full force with consistency. Dolphins can use their neuroticism in a positive way by fully committing to my recommended changes for an entire week. I urge patients to make their chronorhythm (below) a new obsession and compulsion;
get five to fifteen minutes of direct sunlight to activate your SCN during your workout or cool-down.
Jump-start with a cool shower and a high-protein breakfast. If you have done a few cardio moves as recommended, by all means, rinse off. Since a hot shower might lower core body temperature (it sends blood to the extremities), take a cool shower instead, as cool as you can stand it to rush the blood into your vital organs, raise core temperature, and trigger “I’m awake now” hormonal secretions.
Before you take a single bite of breakfast, drink a large glass of room-temperature water. Everyone is dehydrated after a night’s rest, especially Dolphins, whose metabolism works overtime overnight.
Carbs increase the production of serotonin, the “comfort” hormone.
When you’re slightly tired, your hyperactive, creative mind is primed to do what it does best: connect the dots, no matter how disparate and misaligned they seem. If you are into journaling or jotting down big-picture ideas,
Recharge. Do not nap! Napping lowers the buildup of sleep pressure, making it harder to pass out at bedtime, already
Schedule fifteen to thirty minutes for quiet alone time to decompress. Your hyperactive mind will become increasingly anxious as the night wears on and cortisol levels rise. Starting the evening with quiet alone time can ward off or lessen those hormonal and emotional reactions.
To reap the benefits of a retrained brain and reset chronorhythm, you have to be consistent.
8:00 P.M. TO 8:30 P.M. Typical: “I get a lot done, or try to. I might set out to do one thing and get distracted by something else, especially online. There is always a chore or thing I have to do.” Optimal: Have sex, either with a partner or by yourself. It might seem odd to do it at 8:00 p.m., but post-dinner, pre-bedtime sex serves a couple of purposes for you.
Lions’ cortisol level elevates and their melatonin wanes very early, typically at 3:30 to 4:00 a.m., which is why their eyes snap open before dawn. They don’t struggle with sleep inertia, either. In a Lion’s brain, the “white matter”—the fatty tissue in the frontal and temporal lobes of the corpus callosum that connects “gray matter” areas and allows nerve cells to communicate with each other—tends to be in excellent condition.
A Canadian and French study3 found that keeping regular mealtimes and hitting the hay early can ward off anxiety and depression and can even prevent bipolar and schizophrenic episodes in people suffering from those disorders. Numerous studies have confirmed that going to bed early is heart-healthy and BMI-friendly, which isn’t too surprising, considering that late-night junk food consumption is a major cause of both arterial plaque buildup and weight gain. Lions are asleep when Wolves and Bears binge.
When Lions are tired and mentally fuzzy, they come into their creative and insightful powers. Stop trying to stay alert and on point. If you have freedom at work, this is the time to go purposely off point and think outside the box. Brainstorming meetings could yield innovative ideas.
7:30 a.m. to 9:00 a.m.: Cool shower, get dressed, interact with friends or family before heading to work. 9:00 a.m.: Small snack: 250 calories, 25 percent protein, 75 percent carbs. Ideally, have it at a breakfast meeting. 10:00 a.m. to 12:00 p.m.: Personal interactions, morning meetings, phone calls, emails, strategic problem solving. 12:00 p.m. to 1:00 p.m.: Balanced lunch. Go outside for sunlight exposure, if possible. 1:00 p.m. to 5:00 p.m.: Creative thinking time. Listen to music, catch up on reading and journaling. In a workplace setting, lead or attend brainstorming meetings. 5:00 to 6:00 p.m.: Exercise, preferably outdoors, followed by a cool shower. 6:00 p.m. to 7:00 p.m.: Dinner. Keep it balanced—equal parts protein, carbs, and healthy fats. A carb-heavy meal like pasta might make you crash. 7:30 p.m.: Last call for alcohol. A drink after this hour will knock you out. 7:00 p.m. to 10:00 p.m.: Socialize on the town, or connect with loved ones online while relaxing at home. You bought yourself an extra hour, so make the most of it! 10:00 p.m.: Be in your home environment by now. Turn off all screens to begin the downshift before bed. 10:30 p.m.: Go to sleep.
That attraction might be affected by bio-timing. According to a University of Texas at Austin study,1 men can detect a woman’s fertility based on smell alone.
The Rhythm Recap The attraction rhythm: When you feel drawn to a new love interest, thanks to pheromones and the halo effect. The affection rhythm: When you feel the urge to be physically close with a new partner, thanks to the spike in love hormones. The attachment rhythm: When you feel a long-term bond with a partner, thanks to the steady flow of love hormones. THE WORST TIME TO FALL IN LOVE 11:00 a.m. to 2:00 p.m. Morning oxytocin, testosterone, and dopamine levels have receded by then (even for Wolves). For all chronotypes, positive affect is lower at the heart of the workday. Lunch dates may be a great way to meet a person and get to know him or her, but dinner is when you become attracted. THE BEST TIME TO FALL IN LOVE Dolphin: 8:00 p.m., in the afterglow of a serotonin-boosting dinner of mainly carbs, and after sex, which releases oxytocin. Lion: 7:00 a.m., after morning sex. Bear: 4:00 p.m., in the afterglow of a nap, brimming with positive affect. Wolf: 11:00 p.m., in the afterglow of a serotonin-boosting dinner and oxytocin-producing sex.
The Cornell study also looked at chronotype phone-calling preferences and confirmed that morning types are motivated to call friends and engage socially during
The Rhythm Recap The availability rhythm: When someone is most likely to have the time and attention to answer a call, based on work and family schedule. The intimacy rhythm: When to call someone, based on the depth and closeness of the relationship. The bio-time calling rhythm: When to reach out, according to the chronotype of the person receiving the call. THE WORST TIME TO CALL A FRIEND 9:00 a.m. to 3:00 p.m.; 6:00 p.m. to 9:00 p.m. Don’t make social calls during work and school hours. If you must contact a friend during the workday, text. Also, don’t call at dinnertime, when someone might be spending quality time with family or might be out on a date. THE BEST TIME TO CALL A FRIEND Since your goal is to place phone calls that strengthen social relationships, the question is, “When will your friend be most happy to hear from you?” Don’t call according to your chronotype. Call according to his or hers. If your friend is a… Dolphin: 9:00 p.m. to 10:00 p.m. Lion: 7:00 a.m. to 10:00 a.m. Bear: 8:00 p.m. to 10:00 p.m. Wolf: 9:00 p.m. to 11:00 p.m.
The first and most important time-wise tip: Don’t pick a fight unless you’ve had a decent night’s sleep. Call it the sleep-deprivation rhythm—the “you’re overreacting” rhythm.
What about the resolution rhythm—the “don’t go to bed angry” rhythm? That old saying should be changed to “don’t argue before bed.” During deep sleep, the brain consolidates memory. If you have a big screaming fight at midnight and then go to sleep, your brain will cement the negative emotions of the fight in your mind overnight even if you made up beforehand.
Do not rattle a Lion’s cage between 3:00 p.m. and 8:00 p.m.
Do not pick a fight with a Dolphin or a Bear until after 4:00 p.m., or it’ll seem like you’re fighting with yourself.
Lions, Dolphins, and Bears rate lower on impulsivity and future-orientation11 than Wolves, but they, too, are vulnerable to saying things when they’re off-peak that they can’t take back. Wolves, on the other hand, are unlikely to hold their tongues ever and will say anything to win an argument now. When Wolves are off-peak (mornings and mid-afternoon), they might be crankier, but they’ll also be slightly less acidly articulate.
The Rhythm Recap The sleep-deprivation rhythm: When your emotions are muddled due to lack of adequate rest. The resolution rhythm: When to resolve a fight so it doesn’t linger in your mind. The mood rhythm: When mood affects the likelihood of getting in an argument, and its intensity. The self-regulation rhythm: When chronotypes can and can’t hold back from saying something they’ll regret. THE WORST TIME TO FIGHT WITH YOUR PARTNER 11:00 p.m. Fighting before sleep, when you’re both tired and therefore overly sensitive and, for Lions and Bears, at mood low points, is not a good idea. Even if you make up before you turn off the light, sleep immediately after a fight will cement the negative emotions in your mind. Better to argue constructively in the late morning or early afternoon. THE BEST TIME TO FIGHT WITH YOUR PARTNER Dolphin: 7:00 p.m. Dolphins are conflict-averse and good listeners. Wait until after a carb-heavy dinner and they’ll agree to just about anything. Lion: 9:00 a.m. Lions will be alert, analytical, and eager to fix things, although they might not listen well. Bear: 5:00 p.m. Bears might not understand what the fight is about, but they’ll be most willing to compromise when in a good mood. Wolf: 8:00 p.m. Wolves are wide-awake and sharply articulate at this hour, but they’re also in their best mood of the day. Proceed with caution. Fight with Your Partner Compatibility Chart For productive discussion that leads to positive resolution: You : Dolphin Dolphin Partner : 7:00 p.m. Lion Partner : 7:00 p.m. Bear Partner : 5:00 p.m. Wolf Partner : 7:00 p.m. You : Lion Dolphin Partner : 7:00 p.m. Lion Partner : 9:00 a.m. Bear Partner : 3:00 p.m. Wolf Partner : 5:00 p.m. You : Bear Dolphin Partner : 5:00 p.m. Lion Partner : 3:00 p.m. Bear Partner : 5:00 p.m. Wolf Partner : 5:00 p.m. You: Wolf Dolphin Partner: 7:00 p.m. Lion Partner: 5:00 p.m. Bear Partner: 5:00 p.m. Wolf Partner: 8:00 p.m.
Orgasm triggers oxytocin, elevating your mood and sense of connection to your partner all day. When oxytocin levels go up, cortisol levels go down. They’re on a seesaw. More sex, less stress—and less of all the health problems associated with stress, such as obesity, heart disease, and mood disorders. The chemical benefit of sex, that loving feeling, is too often squandered if you have sex and then fall asleep.
The Rhythm Recap The vision rhythm: When your brain is best equipped to fantasize and come up with creative ideas. The logistics rhythm: When your brain is best equipped to analyze the options, research, figure out budgets, and make reservations. The attention rhythm: When your chronotype can sustain attention to detail. THE WORST TIME TO PLAN SOMETHING IMPORTANT At the last minute. THE BEST TIME TO PLAN SOMETHING IMPORTANT Since each chronotype excels at different tasks, it might be smart to divide jobs. In general terms, Dolphins and Lions should take charge of the research and planning. Bears and Wolves should take charge of the vision stuff. That said, here are the best times for each chronotype to do both: Dolphin: Talk about ideas: 8:00 a.m. to noon. Research and solidify plans: 8:00 p.m. to 10:00 p.m. Lion: Talk about ideas: 8:00 p.m. to 10:00 p.m. Research and solidify plans: 6:00 a.m. to 9:00 a.m. Bear: Talk about ideas: 2:00 p.m. to 3:00 p.m.; 6:00 p.m. to 9:00 p.m. Research and solidify plans: 10:00 a.m. to 2:00 p.m. Wolf: Talk about ideas: 8:00 a.m. to noon. Research and solidify plans: 6:00 p.m. to 10:00 p.m.
The distraction rhythm. Children are most open to conversation when they’re distractible (not focused on a task, be it homework, a computer game, or Snapchat) and at low energy (off-peak and tired, as opposed to bouncing off the walls). And when would that be? It depends on the child’s age.
But children are far more likely to fall into one or another category depending on their age. For example: • Infants are majority Wolves, sleepy during the day and active overnight. • Toddlers through kindergartners are majority Lions, waking pre-dawn and then falling asleep early. They benefit greatly from afternoon naps that allow their bodies to recharge. If a toddler or preschooler doesn’t sleep on a Lion’s schedule, it’s probably because he’s habituated to his parents’ schedule or takes long afternoon naps. • Grade schoolers are majority Bears. They wake and fall asleep on a solar schedule and fade out of afternoon napping. • Teenagers are majority Wolves. They are zombies in the morning, with energy surging at night, much to the annoyance of parents who want peace and quiet overnight.
when a child is primed for conversation, consider age more than any other factor. • Ages one to six: Initiate important conversations immediately after lunch and dinner. Little Lions will experience a drop in blood sugar known as the postprandial dip after eating. For about thirty minutes, they slow down but don’t shut down, giving you the perfect window for conversation. • Ages seven to twelve: Initiate talks after school from 3:00 p.m. to 5:00 p.m. during their predictable late-afternoon mood boost. I’ve often advised patients to talk to their kids in the car while driving them to classes and sporting events. The combination of the bio-timing, the side-by-side (not face-to-face) dynamic, and forced enclosure works wonders. But if they have a bad day at school, switch to their topic, and don’t persist with yours. • Ages thirteen to eighteen: Initiate conversations around 10:00 p.m. Teen Wolves are downright gabby late at night. If you can catch them within an hour of bedtime, they’ll surprise you with how much they’re willing to reveal.
Talk to your kids when cortisol levels are low (mid-afternoon or at bedtime), serotonin level is high (after carb-heavy meals or post-exercise), and oxytocin is flowing (after sex or some other kind of affection).
through a day and measured their speed and agility. Early risers performed best in the late morning. Intermediate risers did best in the afternoon. Late risers did best in the evening.
rest rhythm, run in the morning. In an Appalachian State University study,2 researchers had groups of subjects walk on a treadmill at three different times—7:00 a.m., 1:00 p.m., and 7:00 p.m.—and monitored their blood pressure and sleep. The 7:00 a.m. group had a 10 percent drop in blood pressure post-workout and a 25 percent drop later that night, along with a 75 percent increase in deep delta wave sleep—significant improvements compared to those experienced by the 7:00 p.m. walkers.
Major League Baseball players from seven teams. They also asked each player to fill out the Morningness-Eveningness Questionnaire (MEQ). Nine players were evening types, and seven were morning types. For the morning types, the highest batting average (.267) was when game time was at 2:00 p.m., and the lowest (.252) was at 8:00 p.m. game times. The opposite was true for evening types. Their averages were highest (.306) when game time was at 8:00 p.m. and lowest (.259) at 2:00 p.m. games.
Whether you work out early or late, you’re going to see similar results in hypertrophy over a three-month period—if you train daily. The control group that didn’t exercise regularly saw no increase in volume.
Actually, it’s not the concentration of testosterone that matters but the ratio of cortisol to testosterone, or the C/T ratio.12 The ratio of C to T that is most favorable to strength performance is in the afternoon for Lions, the early evening for Bears, and the late evening for Dolphins and Wolves.
their wrists nine times throughout the day. Both groups’ pain tolerance changed significantly from morning to night, but the morning types could take more heat than evening types all day long—50 degrees Celsius vs. 47 degrees Celsius (or 122 degrees Fahrenheit vs. 116 degrees Fahrenheit). This data corroborates the abundance of research about Wolves’ aversion to exercise. They just can’t stand the pain.
THE BEST TIME TO TRAIN FOR STRENGTH Dolphin: 8:00 p.m. Your temperature rises and your cortisol level and heart rate increase at night, ideal for muscle growth and strength. Lion: 2:30 p.m. to 5:00 p.m., your muscle strength window. Bear: 4:00 p.m. to 7:00 p.m. Your body is primed, but if you don’t exercise every day, you won’t increase muscle volume, which, in turn, speeds up metabolism. Wolf: 6:00 p.m. to 7:00 p.m. Routine matters for increasing muscle volume and speeding up metabolism. Although your strength peak comes later, it’s unlikely you’ll actually exercise at 10:00 p.m. Also, exercise within three hours of bed can delay sleep.
Immune function is most active at night, when we are resting, and less active during the day, when we are out and about. The bulk of healing goes on during the first third of a night’s sleep, when your body is recovering from the busy day, and when you undergo physical restoration due to an increase in slow wave deep sleep. However, your white blood cells—the front line of defense—keep their own bio-time, and it doesn’t necessarily stick to the schedule. If white blood cells detect bacteria, infection, or inflammation somewhere inside you, they can go rogue (go on or off their usual bio-time) and attack the bad cells at any time throughout the day. The immunity override rhythm was identified by scientists at Trinity College in Dublin and the University of Pennsylvania.1 They proved that we have an alarm inside each immunity cell that says, “Day or night, it’s time to fight.” Researchers are especially excited about using this insight to develop and improve the new class of “immunotherapy” drugs—custom-made antibodies and proteins that act as the “on” switch to activate our body’s natural defenses to attack the invader, be it bacteria or a tumor, more aggressively.
Timing did make a huge difference. Tumors in mice treated during sleeping hours were smaller than those treated during the day. In the future, it’s likely that EGFR-related cancers will be treated when GC hormones are low—to enhance their effectiveness.
The subjects who slept less than six hours were significantly more likely to get sick than those sleeping seven hours per night. All other variables—gender, health practices, BMI, psychological issues—were ruled out. One hour per night made all the difference.
The fragmented sleep group’s tumors were double the size of, and far more invasive than, the well-rested mice’s tumors. The mushrooming effect was caused not by the cancer cells themselves but by the compromised immunity of the sleep-disrupted mice. Instead of attacking malignant cells in the tumor core (as in the case of the well-rested mice), the immune system of the sleepy mice misdirected white blood cells to blood vessels around the tumors’ edges, promoting rapid growth. The good news: If a certain protein that signals tumor growth—TLR4, or toll-like receptor 4—was blocked, tumor growth was kept in check, even in sleep-deprived mice.
THE BEST TIME TO FIGHT ILLNESS Getting sufficient quality sleep will do as much to fight and prevent disease as quitting high-risk behaviors such as smoking, drinking, and eating junk food. Shoot for seven hours per night. An extra hour can make all the difference. Dolphin: 11:30 p.m. to 6:30 a.m. Lion: 10:30 p.m. to 5:30 a.m. Bear: 11:30 p.m. to 7:00 a.m. Wolf: 12:30 a.m. to 7:30 a.m.
The subjects could withstand pain for longer periods and with greater intensity in the morning.
So when does the body naturally produce antibodies at a faster rate? Fifteen minutes before exercise.
Exercise increases circulation. So getting the blood moving right after receiving the shot helps to spread the vaccine all over your body, increasing widespread production of antibodies.
THE BEST TIME TO GET A FLU SHOT All chronotypes should get a flu shot in early October. Dolphin: 1:00 p.m. Get the shot, and then take a long walk for immunity and an energy boost when you need it. Lion: 4:45 p.m., right before a longer than usual workout. Bear: 11:30 a.m., and then take a long walk to buy lunch and carry it back to work. Wolf: 5:45 p.m. Wear exercise clothes to the pharmacy or doctor’s office, and then walk, jog, or bike home, taking the long way.
caffeine increases breast tenderness and exacerbates the pain of fibroids. In a Duke University study7 of 113 women with fibrocystic breast disease, two-thirds who substantially restricted caffeine for a year reported reduced or eliminated breast pain. Before a mammogram, cut back on caffeinated coffee, tea, and soda for a day or two to make the process easier to take.
Analysis of 380,000 mammograms of women aged thirty-five to fifty-four over an eleven-year time span showed that there were positive readings (when a lump is found) 80 percent of the time during the first week. Breast tissue is less dense then—less swollen from water retention symptomatic of premenstrual syndrome, or PMS—and lumps are easier to spot. Later weeks of the cycle yielded positive readings approximately 70 percent of the time.
THE WORST TIME TO GET A MAMMOGRAM Late in the day, after drinking a pot of coffee, during the last week of your menstrual cycle. THE BEST TIME TO GET A MAMMOGRAM Shoot for the first appointment of the day during the first week of your menstrual cycle.
As a hormone factory, the gut has quite the inventory, and many of the biochemicals it produces run on bio-time.9 • Motilin and ghrelin kick-start the digestive process of cascading muscle contractions, beginning in the stomach. • Gastrin, ghrelin, cholecystokinin, and serotonin keep motility (the movement of food and waste) going through the small intestine and the colon. • Melatonin. You may have thought it was only for sleep, but it has tremendous implications for the gut. It relates to hunger and satiety, and it controls the timing of the digestive process.
When it gets dark out and melatonin starts being secreted from the pineal gland, the GI tract and bowel function are suppressed. When the sun comes up and melatonin turns off—around 8:00 a.m. for Bears—the colon wakes up, too. Most Bears will have their first bowel movement of the day within ninety minutes of waking.
THE WORST TIME TO GO TO THE BATHROOM 1:00 a.m. to 5:00 a.m. Melatonin is flowing in the middle of the night and should suppress your bowel activity. If you have to get up and go in the wee hours, there might be something wrong with your digestive or endocrine system. THE BEST TIME TO GO TO THE BATHROOM Dolphin: Whenever the urge happens. Constipation is an unfortunate side effect of insomnia.11 My advice to insomnia patients is to eat fruits and vegetables at every meal, eat regularly three times a day, and not delay going for convenience or privacy—because that can compound constipation. Lion: 7:00 a.m., an hour after waking. Bear: 9:00 a.m., ninety minutes after waking. Remember to eat a high-fiber diet, eat at regular times, and drink a lot of water. Wolf: 11:00 a.m. Wolves are slower to get started, colon-wise, and might not move for two or three hours after waking. Wolves who commit to eating breakfast will start to go earlier.
• Lions have the most stable personalities, and they’re happiest with their lives, health, and outlook. • Wolves are susceptible to mood swings and addiction, and they’re less happy with their lives, health, and outlook than are other chronotypes.
At the end of the series of sessions, the insomniacs showed significant improvement in both their sleep patterns and depression symptoms.
THE WORST TIME TO SEE A THERAPIST Off-peak alertness times of the day. To keep from falling asleep during the session, and to be sure you’re able to concentrate on the issues, avoid seeing a therapist in the early morning (except Lions) or mid-afternoon. And no one should see a therapist in the evening except for a Wolf. THE BEST TIME TO SEE A THERAPIST I heartily recommend that you seek professional help for an emotional problem, be it short- or long-term, or for expert advice about curing insomnia. To find a traditional therapist, go to http://www.psychologytoday.com. To find a sleep therapist, go to http://www.sleepcenters.org. Dolphin: 4:00 p.m. to 6:00 p.m. Lion: 7:00 a.m. to 12:00 p.m. Bear: 10:00 a.m. to 2:00 p.m. Wolf: 5:00 p.m. to 8:00 p.m.
Lions: Morning meditation will set the tone for the day ahead. • Dolphins: Mini-meditations of two or three minutes can reduce stress on an as-needed basis. Pre-bedtime meditation can reduce cortisol levels and lower blood pressure and heart rate. • Bears: Lunchtime meditation can help boost creativity in the afternoon. Evening meditation can ease the transition from work to home. • Wolf: Mini-meditations of two or three minutes can reduce stress on an as-needed basis. Pre-bedtime meditation helps you transition from peak to sleep.
To help it rise, take a cool (not cold) shower. Lower-temperature water on the surface of your skin causes blood to flow into your core to keep your vital organs warm. So a cold shower actually makes your core temperature rise, waking you up.
A hot-water immersion will cause blood to flow to the extremities (notice how your skin gets flushed after a Jacuzzi or a sauna?) and away from your vital organs, lowering your core body temperature and encouraging sleepiness.
accordingly by time of day. • In the morning, take a tepid or cool shower. A hot shower in the morning will prolong sleep inertia. • Before bed, a hot bath or shower will encourage sleep. A tepid or cool shower at night might suppress it.
THE WORST TIME TO TAKE A BATH OR SHOWER 11:00 a.m. For all chronotypes, a hot shower mid-morning will make you sleepy when you should feel wide-awake. It’s unlikely that showering during on-peak mental alertness times will bring about a creative breakthrough. Your brain is just too focused for lightbulb moments to occur at this hour. THE BEST TIME TO TAKE A BATH OR SHOWER Dolphin: 7:30 a.m. cool shower to help you wake up; 9:00 p.m. hot bath to calm you down before bed. Lion: 6:00 a.m. if you need a morning rinse; 6:00 p.m. post-workout cool shower to stave off evening sleepiness. Bear: 7:30 a.m. cool shower to help wake you up; 10:00 p.m. hot bath to calm you down before bed. Wolf: 11:00 p.m. hot bath to calm you down before bed. No morning shower. It’s better for you to take that time getting
high blood pressure. Nighttime medicine takers had a 33 percent lowered risk of heart attack and stroke compared with the morning pill takers.
Drug: Antihistamines Bio-Time Dosing: evening Drug: Aspirin Bio-Time Dosing: bedtime Drug: ACE inhibitors and ARBs Bio-Time Dosing: bedtime Drug: Acid reflux drugs Bio-Time Dosing: before breakfast Drug: Beta-blockers Bio-Time Dosing: bedtime Drug: Corticosteroids Bio-Time Dosing: afternoon, to reduce overnight inflammation Drug: Heartburn pills Bio-Time Dosing: after dinner Drug: Multivitamin Bio-Time Dosing: after breakfast Drug: NSAIDs Bio-Time Dosing: four hours before maximum pain Drug: Osteoporosis drugs Bio-Time Dosing: an hour before breakfast Drug: Probiotics Bio-Time Dosing: with breakfast Drug: Rheumatoid arthritis drugs Bio-Time Dosing: bedtime Drug: Statins Bio-Time Dosing: bedtime
DANGEROUS TIMES The reason drugs are more or less effective at particular times is because your ailments and conditions fluctuate on circadian rhythms of their own. • Allergies are at their worst in the morning, thanks to nighttime accumulation of pollen. Sufferers wake up sneezing their heads off. • Arthritis. Joints are stiffest between 8:00 a.m. and 11:00 a.m. because your immune system goes into overdrive at night, increasing inflammation. • Asthma attacks strike most often between 4:00 a.m. and 6:00 a.m., when lung function is at its worst. • Depression is at its worst upon waking at 8:00 a.m. • Heart attacks are most common between 6:00 a.m. and noon due to overactive platelets and clotting proteins. • Heartburn strikes after dinner when stomach acids peak and are exacerbated by lying down on the couch or in bed. • High blood pressure will be at its highest at 9:00 p.m. • High blood sugar will be particularly elevated when the liver dumps glucose into your system from 4:00 a.m. to 6:00 a.m. to wake you up. • Hot flashes in menopausal women are most intense and frequent in the late evening around 9:00 p.m. and continuing overnight. • Migraines start forming in your brain at 4:00 a.m. and are most commonly felt upon waking. • Restless leg syndrome is at its most annoying at midnight. • Seizures are most common between 3:00 p.m. and 7:00 p.m. • Strokes are most likely to occur between 6:00 a.m. and noon. • Tension headaches predictably strike in the late afternoon.
Adenosine is a substance in our brains that makes us feel sleepy. Caffeine is an adenosine receptor inhibitor, effectively putting the brakes on sleepiness. This mechanism can be a wonderful thing at 2:00 p.m. Adenosine, a by-product of cellular metabolism, gradually builds up over the course of the day. But upon waking, thanks to your inner clock, you don’t have adenosine in your system. Drinking coffee in the morning is like throwing water on an already extinguished fire. Coffee does give you a hit of adrenaline, which is why people equate it with feeling energized. The problem is, caffeine tolerance builds up over time, and you need to increase the amount of intake to get the effect, just as with any other addicting drug. (See “Have Coffee,” here, to find out the best time to fill your mug.)
researchers asked the subjects to rate their subjective alertness, fatigue, energy, and cognition upon waking and thereafter. • The five-minute nappers reported essentially the same results as the no-nappers—that is, they derived no significant benefits from the super-short nap. • The ten-minute nappers were immediately and dramatically improved across the board, and the benefits were maintained for two and a half hours. • The twenty-minute nappers showed delayed minor improvement. The benefits didn’t kick in for thirty-five minutes, and then they lasted for two hours. • The thirty-minute nappers were immediately and dramatically impaired in all measures for fifty minutes post-nap. When the impressive benefits finally kicked in, they lasted for another hour and a half.
So you have two choices to consider: 1. Nap for less than fifteen minutes—ending the nap before you enter deep sleep—to feel more alert and energized for a few hours. OR… 2. Nap for ninety minutes (cycling all the way back to light wave sleep) to sharpen your focus for the rest of the day.
Nap Wheel, the invention of Sara Mednick, PhD, author of Take a Nap! and researcher on a few of the studies noted in this chapter. According to her data, the Ultimate Nap occurs approximately seven hours post-wake-up, give or take a few minutes, when you are likely to strike the perfect napping balance between slow wave sleep and REM sleep, leaving your mind refreshed with minimal grogginess upon waking.
you nap before seven hours post-wake-up, your nap will be comprised heavily of REM sleep, making you more creative. If you nap after the seven-hour post-wake-up, the nap will be slow wave sleep and will be more physically restorative.
Dolphin: No naps. Napping relieves sleep pressure, the opposite of what you need. Sorry, but a nap would do you more harm than good. Lion: For a wake time of 6:00 a.m., the Ultimate Nap time is 1:30 p.m. Bears: For a wake time of 7:00 a.m., the Ultimate Nap time is 2:00 p.m. Wolf: Naps are not ideal for Wolves if they want to fall asleep by midnight. But if you really need to refresh, for a rise time of 7:30 a.m., the Ultimate Nap time is 2:15 p.m.
refreshed, you need to complete at least four cycles, preferably five. If you wake up mid-cycle, sleep inertia will be hell. Calculate your sleep time by counting backward from your wake time by seven and a half hours (90 minutes x 5 complete cycles = 450 minutes) plus twenty minutes (fall-asleep time), or a total of 470 total minutes. Or, wake time–470 minutes = bedtime.
(Ninety minutes x four cycles) + forty minutes = 400 minutes.
fair to say that eating within an eight- or twelve-hour window makes complete sense for our kind as well, since the GI tract runs on a four-hour ultradian rhythm, smaller time loops within the twenty-four hour circadian rhythm.3 Eating every four hours (within an eight- or twelve-hour window) helps you keep perfect digestive bio-time.
First, booze knocks out the SCN, the master clock located in your brain, and then it seeps down, knocking
The sleep/wake cycle. Drinking in the evening suppresses melatonin release. In a Brown University study,6 researchers monitored the sleep of twenty-nine healthy men and women in their early twenties for ten days. For three nights, half of the subjects drank a placebo beverage, and the other half got vodka one hour before bed. The vodka drinkers’ salivary melatonin was reduced by up to 19 percent. Just one drink can cut your melatonin drastically. • Digestion. Your second brain gets stupid when you drink, too. Since your master clock is affected, your guts don’t know when they’re supposed to do their job releasing proteins and enzymes. The unpleasant result is called “gut leakiness”7 or “leaky gut syndrome.” The bacterial lining of your gut fails to serve as a barrier, so bacteria, viruses, and toxins can leak into (and out of) the intestines, causing bloating, gas, inflammation, headaches, skin conditions, food allergies, fatigue, and joint aches. • Liver function. Your body’s filter and metabolizer operates on its own clock, releasing proteins and molecules on a schedule. Alcohol disrupts that schedule, and in turn, the organ’s mitochondria lose flexibility and start to break down, which causes liver disease.8 Just to be clear: You don’t have to be an alcoholic to do long-term damage to your body and to dismantle circadian rhythms. Chronic use, defined as two drinks a day, is enough to impair your master clock and, by extension, the 100 known minor clocks running on carefully calibrated timing throughout your body. I
The subjects’ ability to metabolize alcohol and clear it out of their system was highest in the evening and lowest in the morning.
Human dehydrogenase is the enzyme that breaks down toxins including alcohol, and it has a circadian rhythm of its own. Call it the bio-time happy hour. Have your wine, beer, or cocktail when those enzymes are flowing in the early to mid-evening—enjoy the drink with friends, and have a conversation without slurring your words.
The Rhythm Recap The tolerance rhythm: When alcohol is metabolized the quickest, so you can drink more with fewer effects. The hangover rhythm: When excessive consumption causes social jet lag symptoms. THE WORST TIME TO HAVE A DRINK Brunch and last call. Early-morning drinking will get you drunker quicker—and sicker quicker. Late-night drinking will disrupt your inner clock and ruin the quality of your sleep. THE BEST TIME TO HAVE A DRINK Dolphin: Bio-time happy hours, 6:00 p.m. to 8:00 p.m. Lion: Bio-time happy hours, 5:30 p.m. to 7:30 p.m. Bear: Bio-time happy hours, 6:30 p.m. to 8:30 p.m. Wolf: Bio-time happy hours, 7:00 p.m. to 9:00 p.m.
• If you drink coffee when cortisol level is high, the effects are nonexistent. Compared to cortisol, caffeine is weak tea. The only thing coffee does for you within two hours of waking is to increase your tolerance for caffeine. • If you drink coffee when cortisol level is low, caffeine gently nudges your adrenals to give you a hit of adrenaline, and you will feel more awake and alert. Scientific research and bio-time have provided a very clear schedule for coffee breaks to coincide with cortisol level dips. For the average Bears, those dips occur between the hours of 9:30 a.m. and 11:30 a.m., and between 1:30 p.m. and 5:30 p.m. (For your chronotype’s optimal coffee window, see “The Best Time to Have Coffee” here.)
Although bright and dim light suppressed melatonin, coffee had the most significant effect, blocking melatonin for forty minutes, enough to ruin a night’s sleep and cause chrono-misalignment.
it can take between six and eight hours for the stimulant effects of caffeine to be reduced by half.
Don’t drink any coffee until your cortisol level dips. Have your last cup before 2:00 p.m. (Dolphins and Wolves) or 3:00 p.m. (Lions and Bears).
THE BEST TIME TO HAVE COFFEE The cortisol level dips or optimal coffee break times for each chronotype are: Dolphin: 8:30 a.m. to 11:00 a.m.; 1:00 p.m. to 2:00 p.m. No caffeinated beverages after 2:00 p.m., including decaf coffee (yes, there is caffeine in decaf). Lion: 8:00 a.m. to 10:00 a.m.; 2:00 p.m. to 4:00 p.m. Bear: 9:30 a.m. to 11:30 a.m.; 1:30 p.m. to 3:30 p.m. Wolf: 12:00 p.m. to 2:00 p.m. No caffeinated beverages after 2:00 p.m., including decaf.
The German study found that people are grumpiest in the morning, get progressively happier in the afternoon, and are happiest in the evening. Extrapolating by chronotype: • Dolphin pleasantness peak: 4:00 p.m. • Lion pleasantness peak: 2:00 p.m. • Bear pleasantness peak: 6:00 p.m. • Wolf pleasantness peak: 8:00 p.m.
activation is at medium intensity in the morning, at peak in the afternoon, and lowest in the evening. Extrapolating by chronotype: • Dolphin activation peak: 4:00 p.m. • Lion activation peak: 12:00 p.m. • Bear activation peak: 2:00 p.m. • Wolf activation peak: 5:00 p.m.
Ask for a Raise Compatibility Chart You : Dolphin Dolphin Boss: 4:00 p.m. Lion Boss: 3:00p.m. Bear Boss: 5:00 p.m. Wolf Boss: 5:00 p.m. You : Lion Dolphin Boss: 3:00 p.m. Lion Boss: 1:30 p.m. Bear Boss: 3:00 p.m. Wolf Boss: 3:30 p.m. You : Bear Dolphin Boss: 3:30 p.m. Lion Boss: 2:00 p.m. Bear Boss: 4:00 p.m. Wolf Boss: 4:00 p.m. You : Wolf Dolphin Boss: 4:30 p.m. Lion Boss: 3:30 p.m. Bear Boss: 4:30 p.m. Wolf Boss: 5:00 p.m.
Data was also calculated to determine the daily mood shift rhythm for successful cold calling, or the best time of day to connect with a person: • 7:00 a.m. to 8:00 a.m.: Very early morning is the worst time to connect, and it’s not hard to understand why. Only Lions are in work mode at that hour. • 8:00 a.m. to 10:00 a.m.: First thing in the morning is a great time to connect due to morning procrastination. Dolphins, Bears, and Wolves aren’t yet at their peak focus and concentration, so they’ll pick up the phone and waste time chatting for a minute. • 10:00 a.m. to 2:00 p.m.: The heart of the workday is not a good time to connect, especially if reaching out to Bears. They’re at peak performance from 10:00 a.m. to 2:00 p.m. and are focused on their own work. • 2:00 p.m. to 4:00 p.m.: Bad time to call, due to the post-lunch cortisol level dip that puts everyone (except Lions) into an afternoon lull. • 4:00 p.m. to 6:00 p.m.: The hands-down best time to connect is in the late afternoon, when the post-lunch dip has subsided. Dolphins, Bears, and Wolves have an uptick in energy and mood and will be open to listening to your pitch. • 6:00 p.m. to 7:00 p.m.: Don’t bother. Obviously, people are ready to leave the office, if they haven’t left already.
Dolphin: 4:00 p.m. to 6:00 p.m., your optimal “in the zone” time. Lion: 8:00 a.m. to 10:00 a.m., your optimal “in the zone” time. Bear: 4:00 p.m. to 6:00 p.m., when you hit a second wind of alertness and are in a good mood and can handle rejection better. Wolf: 4:00 p.m. to 6:00 p.m.,
TIME-WISE TIPS TO PREVENT DROWSY DRIVING ACCIDENTS • Spray peppermint aromatherapy in the car, eat peppermint candy, or chew mint gum. The smell is revitalizing. • Get some exposure to bright lights. • Do some light exercise at rest stops, such as push-ups against the car. It gets blood flowing and will wake you up. Stopping for exercise will block “road hypnosis,” when you’re zoned out behind the wheel. • Listen to a comedy podcast. Laugher and active listening increase alertness. • Tickle the roof of your mouth with your tongue. Just try it. • Nap-a-latte: Drink six to eight ounces of lukewarm or iced coffee and then take a twenty-minute nap. The nap decreases sleep drive. When you wake up, the caffeine will have kicked in. • Drive with a partner. • Take a nap, if possible, before you get on the road.
THE BEST TIME TO EMAIL Dolphin: Professional, 4:00 p.m. to 6:00 p.m. Personal, 9:00 a.m. to 12:00 p.m. Lion: Professional, 7:00 a.m. and 10:00 a.m. to 12:00 p.m. Personal, 3:00 p.m. to 5:00 p.m. Bear: Professional, 10:00 a.m. to 2:00 p.m. Personal, 4:00 p.m. to 6:00 p.m. Wolf: Professional, 4:00 p.m. to 7:00 p.m. Personal, 10:00 a.m. to 12:00 p.m.
When Lions did the hardest tasks in the morning, their middle frontal gyri (in the cerebral region and responsible for executive decision making and higher information) lit up more than the evening types’. Lions’ and Wolves’ brains rely on different regions when they are challenged to learn at their peak mental capacity. Chronotype isn’t only about when you wake up and feel tired. It’s about how your brain works. (This facet of chronobiology isn’t necessarily relevant to when each type learns—but it sure is cool.)
THE BEST TIME TO LEARN SOMETHING NEW Dolphin: 3:00 p.m. to 9:00 p.m., awake enough and at the peak of your learning curve. Lion: 8:00 a.m. to 12:00 p.m., wide-awake and at the peak of your learning curve Bear: 10:00 a.m. to 2:00 p.m., wide-awake and at the peak of your learning curve. Wolf: 5:00 p.m. to 12:00 a.m., awake enough and at the peak of your learning curve.
“On” Times to Make a Decision Dolphin: 10:00 a.m.–2:00 p.m.; 4:00 p.m.–10:00 p.m. Lion: 6:00 a.m.–11:00 a.m.; 2:00 p.m.–9:00 p.m. Bear: 8:00 a.m.–1:00 p.m.; 3:00 p.m.–11:00 p.m. Wolf: 12:00 p.m.–2:00 p.m.; 5:00 p.m.–1:00 a.m. “Off” Times to Make a Decision Dolphin: 9:00 p.m.–6:00 a.m.; 2:00 p.m.–4:00 p.m. Lion: 10:00 p.m.–6:00 a.m.; 11:00 a.m.–2:00 p.m. Bear: 1:00 p.m. to 3:00 p.m.; 12:00 a.m.–8:00 a.m. Wolf: 1:00 a.m.–12:00 p.m.; 2:00 p.m.–5:00 p.m.
THE WORST TIME TO MAKE A DECISION First thing in the morning and the middle of the night.
deliberation. If the phone rings at 3:00 a.m. and you’re asked to make a decision, put it off until morning. Unless you’re a doctor or the president, the emergency can wait. THE BEST TIME TO MAKE A DECISION Dolphin: 4:00 p.m. to 11:00 p.m. Lion: 6:00 a.m. to 11:00 a.m. Bear: 3:00 p.m. to 11:00 p.m. Wolf: 5:00 p.m. to 12:00 a.m.
But first, a quick explanation of how memory works. Using song lyrics as an example, here’s how the three-step memory-making process works: 1. Acquisition. You hear “Hello” by Adele on the radio. 2. Consolidation. The words “Hello from the other side / I must have called a thousand times” solidify in your mind. 3. Recall. When you hear the song “Hello” twenty years from now, you’ll be able to sing every line.
New York University scientists studied22 the neural activity of mice and found that a period of sleep immediately after learning a new skill encouraged the growth of synapses in the brain that were specifically related to what you just learned.
Regardless of when the three groups were trained and later tested, all of them had better recall in the afternoon.
THE WORST TIME TO MEMORIZE After a bad night’s sleep and first thing in the morning. THE BEST TIME TO MEMORIZE For all chronotypes, a good night’s sleep is essential for acquiring, consolidating, and recalling memories. Memory acquisition happens all day long. As for the other two hurdles of memory: Dolphin: Consolidation, 4:30 a.m. to 6:30 a.m. Recall, 3:30 p.m. Lion: Consolidation, 3:30 a.m. to 5:30 a.m. Recall, 2:00 p.m. Bear: Consolidation, 4:00 a.m. to 7:00 a.m. Recall, 5:00 p.m. Wolf: Consolidation, 5:00 a.m. to 7:00 a.m. Recall, 6:00 p.m.
Respondents were most flexible about fitting in a meeting between 2:30 p.m. and 3:00 p.m. The second best time: 10:00 a.m. to 11:00 a.m. • Respondents were the least flexible at 9:15 a.m. The second worst time: 12:00 p.m. to 1:00 p.m. (lunch). • Tuesday afternoons got the highest flexibility scores, and Monday mornings got the lowest number of flexible times.
THE WORST TIME TO PRESENT YOUR IDEAS 9:00 a.m., 2:00 p.m., and 6:00 p.m. In the early morning, people are dealing with sleep inertia and are not at their energetic peak. In the post-lunch body temperature dip, energy is also at a low point. At the end of the workday, people’s focus is tapped out and their attention span is down (Wolves are the exception). Even if you’re in the zone, your audience will be zoned out. THE BEST TIME TO PRESENT YOUR IDEAS Make your presentation short and sweet—twenty minutes or less. If you have the power to set the presentation time, choose a time during an on-peak energy and alertness window: Dolphin: 4:00 p.m. to 4:20 p.m. Lion: 10:00 a.m. to 10:20 a.m. Bear: 1:40 p.m. to 2:00 p.m. Wolf: 5:00 p.m. to 5:20 p.m.
In the morning, they found bilateral links in the medial temporal regions, meaning your mind is making all kinds of connections that trigger fresh avenues of thought. In the evening, MRI scans show frontal and parietal brain correlations, meaning the brain is busy retrieving memories and not creating new ideas.
THE WORST TIME TO BRAINSTORM 11:00 a.m. to 3:00 p.m. It’s a sad irony that you’re at your least creative at the heart of the workday, when brainstorming is demanded of you. THE BEST TIME TO BRAINSTORM Dolphin: 5:00 a.m. to 8:00 a.m., 2:00 p.m. to 4:00 p.m. Lion: 4:00 a.m. to 6:00 a.m., 8:00 p.m. to 10:00 p.m. Bear: 6:00 a.m. to 8:00 a.m., 9:00 p.m. to 11:00 p.m. Wolf: 7:00 a.m. to 9:00 a.m., 10:00 p.m. to 1:00 a.m.
THE WORST TIME TO PUT IT ALL TOGETHER 10:00 a.m. to 2:00 p.m. for Lions and Bears; 4:00 p.m. to 11:00 p.m. for Dolphins and Wolves. Peak alertness hours are for accumulating input that will become future memories (or clues, if you will). Don’t bother trying to put the pieces together then. Instead, soak up information and sensory experiences. THE BEST TIME TO PUT IT ALL TOGETHER Dolphin: 4:00 to 7:00 a.m., during REM sleep and for half an hour after waking. No naps for Dolphins! Lion: 3:00 to 6:00 a.m., during REM sleep and for half an hour after waking. 3:30 p.m., after waking up from a ninety-minute nap. Bear: 4:30 to 7:30 a.m., during REM sleep and for half an hour after waking. 4:00 p.m., after waking up from a nap. Wolf: 5:00 to 8:00 a.m., during REM sleep and for half an hour after waking.
THE WORST TIME TO WRITE A NOVEL 2:00 p.m. to 3:30 p.m.; 12:00 a.m. to 7:30 a.m. The only times you shouldn’t be writing or editing your novel? When you should be napping or sleeping, and consolidating memories and making remote associations that will help you to create the next day. THE BEST TIME TO WRITE A NOVEL Dolphin: Write, 8:00 a.m. to 10:00 a.m. Edit, 4:00 p.m. to 6:00 p.m. Lion: Write, 8:00 p.m. to 10:00 p.m. Edit, 6:00 a.m. to 8:00 a.m. Bear: Write, 6:00 p.m. to 11:00 p.m. Edit, 10:00 a.m. to 2:00 p.m. Wolf: Write, 8:00 a.m. to 11:00 a.m. Edit, 6:00 p.m. to 10:00 p.m.
THE WORST TIME TO BUY Defining “worst” as when you’re most susceptible to overspending: • Female shoppers: A week before your period, two hours before a meal. • Male shoppers: Two hours before a meal. THE BEST TIME TO BUY Defining “best” as when you’re least susceptible to overspending, purchase when you’re (1) not hungry, (2) in an energy lull, and (3) at an arousal low point. That is, buy after lunch. Dolphin: 1:00 p.m. Lion: 12:00 p.m. Bear: 2:00 p.m. Wolf: 3:00 p.m.
THE WORST TIME TO GET RICH 12:00 p.m. to 2:00 p.m. At lunchtime, all chronotypes are alert and focused, and therefore not daydreaming or in risk-taking mode. THE BEST TIME TO GET RICH Dolphin: 9:00 a.m. to 12:00 p.m., sleep inertia daydreaming. Lion: 6:00 a.m. to 9:00 a.m., when you’ve got the working world to yourself. Bear: 7:00 a.m. to 9:00 a.m., sleep inertia daydreaming. 8:00 p.m. to 11:00 p.m., evening daydreaming Wolf: 7:30 a.m. to 10:00 a.m., sleep inertia daydreaming. 9:00 p.m. to 12:00 a.m., evening daydreaming.
The Simple Science By now, you already know that you’re at your sharpest, strongest, and clearest during peak alertness hours. • Dolphin: Mid-afternoon • Lion: Early morning • Bear: Mid-morning • Wolf: Early evening
THE WORST TIME TO MAKE A DEAL Right before lunch, especially after a sleepless night. You will cave. THE BEST TIME TO MAKE A DEAL Dolphin: 2:00 p.m., after lunch and the postprandial afternoon dip in energy and attention. Lion: 8:00 a.m., after breakfast. Bear: 3:00 p.m., after lunch and the postprandial afternoon dip in energy and attention. Wolf: 4:00 p.m., after lunch and the postprandial
THE WORST TIME TO SELL Before 10:00 a.m. and after 10:00 p.m., when you’re most likely to appear tired, which affects the perception of your trustworthiness. Also, you’ll be off your cognitive flexibility peaks in the early mornings and late nights. THE BEST TIME TO SELL Dolphin: 5:00 p.m. to 9:00 p.m. Your cortisol is flowing, making you wide-awake and cognitively agile. Take advantage and sell! Lion: 10:00 a.m. to 3:00 p.m. Quit before your cortisol level drops in the afternoon, and you start to feel (and look) tired. Bear: 10:00 a.m. to 6:00 p.m. Bears make great salespeople and will be at their best from mid-morning to mid-evening. Take a break in the afternoon to reset your cognitive flexibility and you’ll be good to go. Wolf: 4:00 p.m. to 10:00 p.m. Take the closing shift, work the phones, or schedule meetings when your face appears wide-awake, your cortisol is pumping, and you’re ready to dazzle.
THE WORST TIME TO BINGE-WATCH YOUR SHOWS After 10:00 p.m. All chronotypes with social-norm work schedules should turn off all screens by 10:00 p.m. to begin your nightly Power-Down Hour (see here). This includes hand-held devices. THE BEST TIME TO BINGE-WATCH YOUR SHOWS Dolphin: 10:00 a.m. to 2:00 p.m. A morning/afternoon stretch during sleep inertia. By afternoon, your laser clarity kicks in, and that’s when the TV should go off. Lion: 7:00 p.m. to 10:00 p.m., when you’re winding down. Lions who have the occasional bout with insomnia should not watch in bed with hand-held devices. Bear: 3:00 p.m. to 9:00 p.m. on weekends. Don’t fall into the trap of staying up all night on Saturday. It’ll wreck your sleep patterns for the upcoming workweek. Wolf: 5:00 p.m. to 11:00 p.m. on weekends. Don’t fall into the trap of staying up all night on Saturday. It’ll wreck your sleep patterns for the upcoming workweek. Wolves should not TV binge alone. If you have a friend or family member watching with you, you’ll be able to cut yourself off and stop the “one more episode” spiral.
THE WORST TIME TO LOG ON On-peak productivity hours, depending on chronotype; within an hour before bedtime. By now, you should know your on-peak times and bedtime. Log off one hour before sleep so you don’t disrupt the flow of nighttime melatonin. THE BEST TIME TO LOG ON Dolphin: 9:00 a.m. to 3:00 p.m. Block browsing until 9:00 p.m. Log off by 10:30 p.m. Lion: 6:30 a.m. to 6:00 p.m. Log off by 9:00 p.m. Bear: 8:00 to 11:00 a.m. Block all but work-related sites until 7:00 p.m. Log off by 10:00 p.m. Wolf: 9:00 a.m. to 3:00 p.m. Block browsing until 10:00 p.m. Log off by 11:00 p.m.
THE WORST TIME TO PLAY GAMES 2:00 a.m., even for Wolves. When you’re tired, you’re likely to cheat, have less fun, make poor judgments, and lose your shirt. THE BEST TIME TO PLAY GAMES Dolphin: Games that require insight, 10:00 a.m. to 2:00 p.m. Games of chance and games that involve strategy, 4:00 p.m. to 10:00 p.m. Lion: Insight, 5:00 p.m. to 9:00 p.m. Chance/strategy, 7:00 a.m. to 3:00 p.m. Bear: Insight, 6:00 p.m. to 10:00 p.m. Chance/strategy, 10:00 a.m. to 2:00 p.m. Wolf: Insight, 8:00 a.m. to 2:00 p.m. Chance/strategy, 4:00 p.m. to 11:00 p.m.
THE BEST TIME TO READ FOR PLEASURE Open your mind and eyes to the written word every day for multidimensional benefits to the mind and spirit. I recommend reading during your nightly Power-Down Hour in preparation for sleep. Dolphin: 10:00 p.m. Lion: 9:00 p.m. Bear: 10:00 p.m. Wolf: 11:00 p.m.
Note: The guidelines below are for traveling at least three time zones. If you’re traveling one or two time zones, you’ll need to follow the strategies for day one only or not at all. The human body needs one day per time zone traveling to adapt. Traveling East, or Phase Advance (Waking Earlier; Going to Bed Earlier) • Day of flight: No caffeine at all. Adjust your watch to your new time zone. • During flight: After two hours on the plane, attempt to sleep for the remainder of the flight. Use the complimentary eye mask and earplugs, or bring your own. If you can’t sleep, avoid light and/or wear sunglasses. • Upon landing at your destination: Put on shades if they’re not already on. • Day one at your new destination: Wear sunglasses until 12:00 p.m. After 12:00, take your sunglasses off, and get as much direct sunlight as possible, especially between 1:30 p.m. and 4:30 p.m. If you’re stuck inside all afternoon, take sunshine breaks for ten minutes each hour. You can have caffeine upon arrival, but no later than 3:00 p.m. Eat breakfast, lunch, and dinner (here) on your new schedule, even if you’re not hungry. Exercise in the afternoon, preferably outdoors. Naps: no! A sleep aid can help you sleep later the first night.28 NASA recommends using one, too. Don’t bother setting an alarm. Sleep in as long as you can. • Day two: Put on your sunglasses upon waking and keep them on until 10:00. After 10:00, take the sunglasses off and get as much direct sunlight as possible, especially from 11:30 to 2:30. If you’re stuck inside, take sunshine breaks every hour. Caffeine: yes, but no later than 3:00 p.m. Eat on your new schedule, even if you’re not hungry. Exercise in the afternoon, preferably outdoors. Naps: no! • Day three: You’ll feel normal by this morning, but continue wearing sunglasses before 9:00 and getting direct sunlight after 9:00 on an hourly basis. • Day four: Congrats! You are now comfortably on a Bear’s chronorhythm at your new time zone. Traveling West, or Phase Delay (Waking Up Later; Going to Bed Later) • Day of flight: No caffeine before the flight. Set your watch for your destination time zone. Wear sunglasses all day until the flight. • During flight: As soon as you get comfortable, put on an eye mask and ear buds and listen to a relaxation audio program (go to http://www.thepowerofwhen.com for a download), and attempt to sleep. If the flight is long enough, use a sleep medication.29 No caffeine for the duration of the flight. Wear sunglasses until the last two hours of the flight. Then take them off and get as much sunlight as possible through the plane window or artificial light with close-up screen exposure. • Day one at your new destination: The sunglasses off, get as much direct sunlight as possible, especially in the evening. Use screens at night until bedtime. No caffeine after 6:00, and no naps. Exercise before noon, and eat on your new schedule, even if you’re not hungry. • Day two: Get as much direct sunlight as possible, morning…
THE WORST TIME TO TRAVEL When drunk. One drink in the air is more intoxicating than one drink on the ground (due to in-flight dehydration). THE BEST TIME TO TRAVEL For flights that take you three time zones or more from home: Dolphin: Daylight hours, to save yourself a night of plane-related insomnia. Lion: Late evening. For an overnight flight, you’ll do slightly better to arrive very early in the morning. Bear: Overnight, at your flight schedule convenience. Wolf: Midnight. Take the last plane out, and you’ll be able to sleep better during the flight.
In the days leading up to the full moon, melatonin started dropping dramatically, hitting its lowest level on the night of the full moon. Melatonin rose to its highest level at day fourteen or fifteen of the twenty-nine-day lunar cycle.