3 Ways to Give Your Circadian Rhythms a Tune-Up

Whether you’re a lark or an owl depends on your chronotype, a propensity to be alert at a particular time of day. Your chronotype is, for the most part, biologically hardwired. It's determined by a complex system of biological cycles in the brain and body called circadian rhythms. These rhythms are like billions of clocks, running the daily itineraries of our metabolism, hormone secretion, cognitive function, physical performance, and even gene expression. If this network were to lose its rhythm...well, imagine if every clock in the world ran at a different speed.

On average, a human's circadian rhythms cycle every 24.1 hours, nearly matching the earth’s rotation. If you were born a lark, congratulations! Society is designed for you and your near-24-hour rhythms. But some people's cycles are longer, so their natural sleepy time gets pushed later and later every day relative to society’s 24-hour clock. These people ("owls") are always swimming against the current of their biology, having to drag themselves out of bed in the morning but buzzing with energy when they "should" be sleeping at night.

And it's not only a problem of inconvenience. People with owl chronotypes are at greater risk for psychiatric disorders, addiction, hypertension, obesity, type 2 diabetes, and even infertility. This is due, at least in part, to the circadian misalignment that results from living as an owl in a lark’s world. For example, do you sleep in for hours on weekends? Stay on your iPad late at night? Wear sunglasses in the morning because you’re just not ready to look human yet? These (completely understandable) habits constantly change up the cues—such as light—that your circadian system uses to keep time. When your clocks get confused, all of your biological operations suffer.

The cavemen and women who couldn't stop fidgeting after moonrise may have helped to save the whole tribe from nocturnal predators!

But don’t worry, owls. Your chronotype can adapt to the 24-hour world with your help. Follow these three tips to re-tune your clocks for a healthier and happier life.

Tip #1: Get a dose of bright light first thing in the morning.

Light is the strongest cue that your circadian system uses for telling time. Your retina sends direct signals to the suprachiasmatic nucleus, the brain’s master clock, so letting light enter your eyes in the morning tells the whole network that it’s time to gear up. Doing this consistently helps your circadian system to stay on track, which not only tunes your clock but also improves mood.

Tip #2: Minimize bright light exposure at night.

Also, don’t confuse your circadian system by getting too much bright light at night. The short wavelength light from phones, TVs, and other modern technologies tricks our circadian clocks into thinking it’s daytime when it’s not, and this has been associated with serious health problems like diabetes and cancer. The good news is that you can help your chronotype to adapt. One recent study found that after one week of camping without electronic devices, owls’ melatonin profiles—the most precise measure of internal circadian rhythms—became indistinguishable from larks’. Since most of us can’t go camping everyday, you can mimic the “campfire effect” at home by limiting device use after sunset or wearing blue light blocking glasses.  

Tip #3: Wake up at the same time every day.

When you sleep in on weekends, you’re giving yourself "social jetlag." Catching those extra 2 or 3 hours on Saturday is like flying your body from New York to Los Angeles. This is a major stressor for your circadian system. It not only makes Monday mornings feel awful, but can affect your overall mental health through increased risk for depression and addiction. Also, because your clocks are so intimately linked with metabolism, it’s no wonder that social jetlag is also linked to obesity. If you absolutely cannot get up at the same time every day, minimize sleeping in on weekends, and make your morning routine more efficient so you can wake up later on weekdays.

One note to the larks: instead of stigmatizing night owls as lazy or irresponsible, you should appreciate us. After all, owls likely exist as evolution's answer to our cavemen ancestors' need for vigilante night guards. The cavemen and women who couldn't stop fidgeting after moonrise may have helped to save the whole tribe from nocturnal predators!