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What You Need to Know About Your Circadian Rhythm

Learn how to maximize your internal timing system.

October 2026
By Lynne Peeples

Ever wonder why you can barely keep your eyes open in first period yet you often feel wide awake at 10 p.m.? The answer has to do with your circadian rhythm. This internal timing system tells your body when to perform certain tasks, like sleeping, digesting a meal, or releasing hormones that help you grow and feel alert. Your circadian rhythm is built into your cells, but it also relies on cues, like light levels. During puberty, circadian rhythms shift, making teens naturally fall asleep and wake up later than younger kids and adults. That’s one reason early school start times can feel so brutal. Here’s what else to know about your circadian rhythm.

Reset Your Rhythm

Your circadian rhythm relies on a few powerful signals. When these signals get mixed up, you might feel sluggish, have trouble focusing, or struggle to fall asleep at night. Here’s how to reset.

Signal: Light

PROBLEM: You spend much of the day indoors and don’t experience the natural contrast between light and darkness. That makes it hard for your body to tell time.

FIX: Get outside, especially in the winter, when daylight is limited. Indoors, spend time near windows. Avoid screens or bright lights after dark.

Signal: Food

PROBLEM: You eat from the moment you wake up until right before bed. But food is easier to digest early in the day, so eating at night can interfere with sleep.

FIX: Don’t eat large meals close to bedtime. If you need an evening snack, try something light, like yogurt with fruit, which promotes relaxation.

Signal: Exercise

PROBLEM: You exercise in the evening, which makes it hard to doze off at night.

FIX: Exercise earlier in the day. If you have a late-night practice or game, help your body wind down afterward with a calming routine, like listening to music or reading under dim lights.

Coping With Daylight Saving Time

The twice-a-year clock adjustment is hard on our internal timekeepers. Here are two ways to make the transitions easier.

GET A HEAD START

Gradually adjust your sleep timing in the days and weeks ahead of a switch so your body doesn’t have to deal with that hour change all at once.

SEEK CONTRAST

Expose your body to bright morning light and dim evening light to help your body adjust faster.

What is Melatonin?

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Melatonin is a hormone controlled by your circadian rhythm that signals when it’s time to sleep. Melatonin supplements can sometimes help with short-term sleep problems. But taking too much or taking them at the wrong time can confuse your internal clock. And because supplements aren’t regulated like medicines, their potency can vary. It’s best to talk with your parents and a doctor before using melatonin—or any supplement.

True or False?

1

Light from your phone can disrupt your circadian rhythm.

True! Bright light of any color can confuse your body clock, but your phone screen’s blue light is especially disruptive. It’s best to avoid screens for at least 60 minutes before bed.
2

You can make up for lost sleep by sleeping in on the weekend.

False! Your body clock hates big swings in your schedule. Sleeping a little late is OK, but keeping to a consistent sleep schedule is just as important as getting enough sleep.
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