Imagine what your day would be like if you did everything at the best time—when your body clock is naturally most in tune with what each kind of activity requires and rewards.

That’s the premise of 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, the new book by sleep expert Michael Breus, PhD.

The reality is, the way you feel and function changes throughout the day, hour by hour, based on your body’s daily (circadian) rhythms. These physiologic ups and downs are orchestrated by 24-hour fluctuations in hormones (such as serotonin, cortisol, dopamine and melatonin), blood pressure and body temperature, explains Dr. Breus, who has done a deep dive into the science of chronobiology to research the new book.

The trick is to match each activity to your appropriate biological peak. Then you’ll find the best time to eat, think, exercise, daydream, talk to friends—even see your dentist—for you. “There’s a never-ending set of peaks, depending on what you want to accomplish,” says Dr. Breus. “It’s all about riding the wave and jumping from one peak to another.”


The “power of when” works whether you’re an early-morning lark or a night owl—it’s just that your peaks will come at different times of the day for you. Most of us, Dr. Breus writes, are one of four “chronotypes.” (To discover which type best describes your own daily rhythms, take this 45-second quiz “What’s Your Chronotype?” developed by Dr. Breus.)

The following “best time to” routine is based on the chronotype that Dr. Breus dubs “Bears.” It’s the most common one, describing about 50% of the population. Bears, writes Dr. Breus, “tend to wake up in a daze after hitting the snooze button once or twice, start to feel tired by mid-to-late afternoon and sleep deeply but not as long as they’d like.”

To adjust to an earlier schedule or later schedule, just shift the numbers to be closer to your starting wake and sleep times.


Before we start, let’s be realistic. You won’t be able to do each of these activities every day—after all, if you have a job, shopping and napping in the afternoon aren’t daily options! Yes, there’s no TV time here, either, but then there’s no ideal time to watch—although there’s an ideal time not to watch (right before bedtime). So don’t consider this an actual schedule. Rather, it’s a guide to the best times to do these activities…

7:00-8:00 am: Wake up—and have sex. While many people have sex before bedtime, sexual desire actually peaks in the morning for most people. That’s when testosterone, which affects sex drive in both men and women, is at its highest, explains Dr. Breus. Plus, having sex in the morning, which can put you in a good mood and flood your brain with feel-good hormones such as oxytocin (the “love hormone”), is a great way to start your day.

8:00-9:00 am: If you need to schedule something that’s uncomfortable, do it now. On most days, you’d eat a hearty breakfast about now, but if you need to have a tooth drilled or get a mammogram, now’s the best time. Pain tolerance peaks in the early morning—no one knows exactly why, but it may be related to the lingering analgesic effects of cortisol, which tends to rise just after you wake up. So if you have any kind of physically uncomfortable or potentially painful event to schedule, get it over with early in the day.

9:00-9:30 am: Organize your day. Alertness and attention build slowly after you wake up and tend to be at a high level by mid-morning—which makes this the perfect time to map out what you plan to accomplish for the rest of the day. Instead of just jumping into the routine task that you didn’t finish yesterday—something you may be able to do when you’re less primed for alertness—step back and think strategically. It’s a great time to make lists.

9:30-11:30 am: Tackle your hardest work problems now. During this window of opportunity, your intellectual capabilities are the highest they’ll be all day. This is an ideal time to learn new information or work through a complicated project.

11:30 am-1:00 pm: Get aerobic exercise such as a walk or do yoga—and then have lunch. If you exercise first before you eat, you’ll speed up your metabolism—and decrease your appetite at the same time, Dr. Breus notes. Plus, it’s a great way to stave off that afternoon lull. “Your core body temperature dips between 1:00 and 3:00 pm,” says Dr. Breus—that may make you feel a little sleepy, but “getting a little exercise beforehand can rejuvenate you.”

1:00-3:00 pm: Do chores—especially shopping. You’re less susceptible to overspending now. Why? Chances are you’re not hungry and your energy is slightly low. Shopping in this state, says Dr. Breus, can help you avoid impulse purchases—which are more common when adrenalin levels are up.

2:30 pm: Take a (short) power nap. A 20-minute nap can restore your energy and alertness. Set an alarm so you don’t sleep longer than that—or else you could wake up with a case of sleep inertia (aka, brain fog), Dr. Breus warns.

3:00-5:00 pm: Make important decisions. Your alertness picks up again in the later afternoon. Now you’ll be better able to make logical, less risky decisions rather than being emotionally reactive when faced with choices, Dr. Breus says. If you’re a little hungry, have a light snack—no more than 250 calories—with some protein, since eating too much can dampen your alertness. Examples: An apple with a tablespoon of almond butter…or a handful of whole-grain crackers with an ounce of cheese.

5:00-7:00 pm: Didn’t exercise at lunch? Go now! Consider a run, a bike ride, lifting weights—or playing a team sport. Why? Your body temperature is higher in the early evening, which means your strength, hand-eye coordination and aerobic capacity are at their peak. This is a great time to get physical.

7:00-8 pm: Eat dinner. Make it the smallest meal of your day—a vegetable-rich stew and a salad, for example—so your body isn’t overwhelmed with digestion when you need to start winding down. You’ll want to finish eating at least three hours before your bedtime.

8:00-9:00 pm: Call a friend or brainstorm. Your alertness and concentration now start to wane, but that means creativity starts to peak, says Dr. Breus. Now is also a good time to play games. So now’s your best time to come up with innovative ideas or have fun conversations with friends and family.

9:00-10:00 pm: Power down. Create a “digital sunset”—power off all screens—at least one hour before bed to help you get in the mood to snooze. This way, the blue light from your screens won’t interfere with the release of melatonin, which helps you fall asleep.

9:00-11:00 pm: Read for pleasure, not purpose. As you power down, reading an engrossing or comforting book lowers your cortisol level—reducing stress—and your heart rate, which helps relax your body and mind. “Your mind will wander a bit and bring the imagery of a book to life,” Dr. Breus says. That’ll put you in a great state for drifting off to sleep.

10:00-11:00 pm: Go to bed. “Your pillow unlocks your potential,” says Dr. Breus. “If you know when the right time to sleep is, everything else falls into place.” Try to keep your bedtime and wake-up time fairly consistent to anchor your body’s rhythms and help you enjoy these hours of power, day after day.

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