What time is it?
If you look at a clock to get the answer, your body probably doesn’t agree. Our sleep, our mood, our alertness, our hunger cycle” — even the rise and fall of our body temperature — ”don’t pay attention to clock time. They follow their own rhythm.
A cluster of nerve cells deep in the brain guides how we function across the day and night. This inner clock works differently from person to person. Yours could easily be off by as much as six hours from someone else’s. And if that someone is your spouse or your boss, you may be in for trouble.
One thing our inner clocks do have in common is that almost all of them have a cycle longer than 24 hours. How much longer is a matter of genetics. Your cycle may last 24 1/2 hours, while the person next to you cycles at 25 hours or 24 hours and five minutes.
Slow types” — call them owls” — prefer later bedtimes, struggle to get up in time for work, have no appetite for breakfast and don’t reach peak functioning until afternoon. Those with faster clocks — ”call them larks” — jump out of bed easily but wear out by the evening.
If you’re an owl, you’re more likely to get depressed without knowing why. When we’re forced to do things that our clock isn’t ready for, ”even if it’s getting to sleep “on time,” ”that’s a formula for low mood, sluggishness, anxiety and frustration. You may think the basic problem is work stress, when really your late inner clock is responsible for creating the stress.
Fortunately, there are ways to reset your inner clock so it ticks with the world outside. Here are five tips to get started:
1. Figure out what time you’re on. Are you an owl, a lark or in between? You can and should find out. Go to http://www.cet.org, the website of the nonprofit Center for Environmental Therapeutics, and take the online Morningness-Eveningness questionnaire.
2. Respect the light of day! The clock in your brain is linked to the outside world through the eyes. When light hits your eyes, they send a message to the clock to slow down or speed up depending on the time of day. Light right after you wake up speeds it up for the next cycle. That’s how we subtract physiological time each day to match the outside world. Not enough morning light, and you’ll fall into a sluggish pattern.
If your inner clock is running very late, brighter light when you wake up may not be enough to make the daily correction. You may need to add bright-light therapy. Bring a light-therapy box to the breakfast table while you look at the paper, check your e-mail or plan your day. This new routine pays off richly in increased energy and readiness to tackle the day’s challenges.
As for bright light in the evening — television, computer screen and shopping mall — it makes the clock slow down more than it is already. It gets harder to fall asleep and you need the alarm to wake you up, without enough sleep. Dim those screens and room lights or use special blue-blocker glasses.
3. Check your liver clock. Our digestive system cycles, too, but its clock is in the liver, not the brain. When we eat, this inner clock adjusts how the body extracts nutrients from food, how much energy will result, and when. Most owls aren’t hungry when they get up. They wait until lunch for a big stomach load, contributing to fatigue and depression.
If this is your pattern, correct it by having a protein-rich breakfast when you get up, even if you’re not hungry. You don’t have to eat much — ”some cheese, a hard-boiled egg, a can of protein shake. This brings the liver clock and the brain clock into sync with each other. You’ll be more alert in the morning and less tempted to eat dinner late, which would interfere with sleep.
Dinner, by the way, should emphasize carbs, in contrast to the protein load at breakfast. Digestion will be quicker, and you’ll fall asleep more easily.
4. Prepare for winter. At this time of year, the sun rises later and later. There’s less natural light to keep our inner clocks in check. About 5% of New Yorkers start to feel significantly depressed about now, in late October. This is seasonal affective disorder, or SAD, and on average it last all the way into early May. The reason is that their inner clocks are reacting to the loss of early morning light. Another 15% aren’t clinically depressed, but they find themselves slowing down, just hanging on with work and family, feeling more fatigued, less sexually and socially interested. If you have these “winter blues,” light therapy can help, and short of clinical depression, you can try it on your own.
5. Try an aerobic boost. Your inner clock will thank you for 30 minutes of power walking or jogging outdoors or using the equipment at your gym. Best results are with morning or midday exercise at a standard hour. (Avoid evening, or you may have insomnia.) Your clockwork stabilizes, you sleep more soundly and the mood and energy lift can last a whole day.
Dr. Michael Terman is director of the Center for Light Treatment and Biological Rhythms at New York-Presbyterian Hospital/Columbia University Medical Center. He is the author of “Chronotherapy: Resetting Your Inner Clock to Boost Mood, Alertness, and Quality Sleep” (Avery), out now.