Simply put, circadian rhythms “are physical, mental, and behavioral changes that follow a 24-hour cycle,” according to the National Institute of General Medical Sciences. These rhythms are centered primarily around light and dark and they help regulate your sleep-wake cycle.

When these rhythms get disrupted, that’s when most people begin to experience poor quality sleep. So how does it work?

During daylight hours, your eyes sense light. This wakes up your brain and keeps you energized and alert throughout the day.

In the evening, your eyes sense light fading. This triggers the brain to produce melatonin (the natural hormone that makes you feel drowsy).

It’s really pretty simple. Day = awake. Night = asleep. But what happens when a wrench gets thrown in your circadian rhythm? And what usually causes it?

Jet Lag

If you’ve ever traveled across time zones, you’ll be familiar with the concept of jet lag. Our brains have an internal biological clock. When you fly across time zones, our internal clock takes time to readjust to the light/dark schedule in your new destination. That’s why you’ll often feel tired and groggy for a few days until your circadian rhythm recalibrates.

Shift Work

If your current work schedule requires you to work through the night and then sleep during the day, your sleep-wake cycle is at constant odds with your circadian rhythm. This can make it difficult to fall asleep easily. And it likely makes it tough to stay alert when you need to.


If you are like most people today, your mobile phone is always in your hand. But artificial light at bedtime can disrupt your circadian rhythm. That’s why we recommend tucking away your electronics and mobile devices a couple of hours before it’s time to fall asleep.

These are just a couple of examples of how your circadian rhythm can get off-kilter. Limiting caffeine after noon, keeping naps short and sweet, staying active during the day, and maintaining a consistent sleep schedule are all additional ways you can help nurture a healthy sleep-wake cycle.

But remember, if your sleep problems persist it’s always a good idea to schedule time with your doctor. Sleep is essential to a happy, healthy, productive life. And taking steps to improve your sleep quality and quantity is worth it.

Additional Reading:

National Institute of General Medical Sciences: What Are Circadian Rhythms?