Long before TV, Social Media and 24/7 email, humans rose with the sun, worked until dusk, then fell into bed when the sky grew dark. That’s how nature designed our bodies to function best: The body’s master clock (a cluster of cells in the brain that regulates nearly every bodily function) is ruled by the 24-hour cycle of sunlight and darkness.
Here’s how this system, known as the Circadian Rhythm, works: As the sun begins to rise, “the master clock receives light input directly from the eye and uses that information to synchronize the 24-hour day. That helps regulate several hormonal processes. Melatonin, which allows us to sleep, plummets, and Cortisol, which revs up energy, increases. Hours later, as night falls and the sun disappears, melatonin levels begin to rise again, winding us down.
More than just your sleep can suffer as a result of this onslaught of unnatural light—it can throw off the secondary clocks in cells in the heart, gut, muscles, and more.
How your circadian rhythm influences your health
Sleep may affect your gut:
Nearly 40% of people who suffer from IBS, which includes constipation and/or diarrhea and other GI difficulties, frequently experience sleeplessness. Researchers are exploring whether circadian dysregulation might impact the trillions of bacteria in the gut, known as the microbiome, and if so, whether supplementation with oral probiotics might counter some of the damage. If so, probiotics may one day be prescribed to protect shift workers, those who serve in the military (who frequently operate under sleep-deficient conditions), and even the average night owl from GI distress.
-Good Sleep influences your heart rate: Adults are two to three times as likely to suffer a heart attack, in the morning than at night, with peak hours between 6 a.m. and noon. When you’re sleeping, everything slows down a bit, including your heart rate, because you don’t need as much blood flow. But as it becomes lighter outside, your body starts to wake up, and your heart rate and blood pressure begin to rise—almost like warming up your engine. In a healthy person, this process is harmless, but in someone with underlying cardiovascular disease, the rise in heart rate and blood pressure may trigger a heart attack.
-If you are on medication for heart disease, ask your doctor if taking it at night might benefit you; a 2018 study showed a 67% reduction in heart attacks and other major cardiovascular events when patients took their meds at bedtime instead of in the morning.
Good Sleep helps your skin heal:
Your skin houses circadian clocks that are more active during the day than at night, and this can influence healing time. Animal studies have found that cuts heal faster when the injury occurs during the day, and data suggests that burns incurred in the daytime heal up to 60% faster than burns that occur at night.
Good Sleep influences your metabolism:
Just as bright light stimulates the brain, it may also help wake up your metabolism. In a 2014 study, found that subjects exposed to early-morning rays had lower BMIs than those exposed to sun in the afternoon; they were also more physically active all day. Light helps synchronize the clocks in the brain and body that regulate appetite and metabolism.
How to sync your Sleep Cycle
Getting your internal clocks working harmoniously is crucial for your health: Picture those clocks as instruments in an orchestra, says St. Hilaire. “The master clock in the brain is the conductor who keeps everyone at the same point in the song.
But if the conductor becomes distracted, you get a cacophony of sound rather than a perfect melody.” That cacophony, known as chronic circadian disruption, can make you feel run-down, crabby, hungry, distracted, and sad, and it may play a part in heart disease, cancer, obesity, and depression. “To get your circadian rhythm back in sync, the simplest rule is to expose yourself to bright days and dark nights,” says Glickman.
Bathe yourself in morning light: Throw open your curtains as soon as you wake; the sunlight will help suppress melatonin production. Still dark outside? Try this trick from Dr. Zee: Buy a programmable blue light box and set it to start brightening 15 minutes before your alarm goes off. Look for a box with a rating of 3,000 to 10,000 lux (check out Aura Daylight and Verilux models), which will feel about as bright as what you’d experience outside on a cloudy day, she says.
Stick to a schedule: Staying up late on Saturday and sleeping in on Sunday may feel delicious in the moment, but it creates a condition called social jet lag. Your best move: Hit the sack and wake up at the same time, give or take 15 minutes, seven days a week. For a weekend indulgence, take a 20-minute nap at around 2 p.m.
Work near a window: If you can snag a windowed office, you may sleep better: One of Dr. Zee’s studies found that office workers with windows slept about 46 minutes longer per night than those not exposed to natural light in the workplace.
Avoid bright light before bedtime: Phones, laptops, and iPads emit blue light, a major component of sunlight, so when you scroll Instagram at 10 p.m., your brain interprets it as “Time to start the day!”
Banish all light at night: Even a little bit of light, like the moonlight seeping in through your blinds or the aura emanating from your phone as it charges by your bed, can confuse your system enough to impede sleep. Consider investing in quality blackout shades; charge your phone in another room; and buy an alarm clock with red or amber light, which will be less disturbing to the circadian rhythm than blue light.
This article originally appeared in the May 2020 issue of Prevention.