How Light Can Actually Help You Sleep Better

How Light Can Actually Help You Sleep Better

Learn more about the science of light and sleep, and how to use it to your advantage.

When I was in high school, my parents took us on a long-planned trip to Alaska in the summer.  Being so far north, the sun wouldn’t set until 11 pm. Much to my parents’ consternation, my younger brothers and I wanted to stay up. I could see a clock and I knew it was late, but I was wired. If you’ve ever been unable to sleep at 11 pm (whether or not you’re in Alaska), you likely know the feeling. Here’s how to remedy it. 

Our bodies have internal biological clocks called the circadian rhythm (CR). For those Latin buffs, “circadian” translates into “around a day,” as the CR cycles on a 24-hour period. It’s a primary driver of when you feel ready to wake-up, the periods you have energy throughout the day (hello, 2 pm slump) and when you fall asleep. Your CR is extremely sensitive to factors in our environment called “zeitgebers” (come on, that’s an awesome word, right?). The most influential zeitgeber? Light.

When we see light, the signal travels through the eye to an area of the hypothalamus that controls melatonin release, the hormone necessary to help you sleep. Since bright light is the brain’s signal to stay awake, it shuts down melatonin production, and signals for other “awake” activities, such as raising your body temperature and cortisol release. Then, in the evening when the sun begins to set, the brain starts to release melatonin, so that you’ll be ready to sleep in about two to three hours. That’s great … if you live in the 1800s. But today, with electricity at all hours, smartphones and late-night Jimmy Kimmel, we’re signaling our bodies to stay alert—not release melatonin on time, making it near impossible to fall asleep when we need.

Technology doesn’t have to do a number on your sleep. Here’s how to hack it to help you sleep (and wake-up!) more easily.

  • Put down the smartphone and step away. Blue light is a particularly strong signal to suppress melatonin. If you have to use a device at night, be sure to set it to “nighttime” mode two to three hours before bedtime, spring for a flashy pair of blue blocking glasses (which have been found to help people with insomnia when worn two to three hours before bed) and, as much as you can, avoid using your devices for the last hour before bed. 
  • Turn down the lights in your bedroom. If your bedroom is lit up like Times Square, just walking into the room at bedtime can dampen your melatonin. At nighttime, individual lights in your bedroom should be 40 watts or less (with a maximum total of 300 watts for all light). I bought a low-wattage bulb with a dimmer for my bedside lamp, and when I head upstairs for bed, it’s the only light I turn on. When I’m washing my face and brushing my teeth, rather than turning on the bright, overhead light, I turn on my closet light.
  • Block ambient light in your bedroom. Even after going to bed, most of us have a variety of ambient lights, from the alarm clock, to the cable TV box, to outside lights. Even small amounts of light can keep us up. Some really unexplained science: One study showed that simply shining light on the back of our knees was enough to impact our circadian rhythm). Cover any blinking or ambient lights, or turn them off if you can. 

Find out how to address other sleep saboteurs in last week’s article, and start getting the zzzz’s that you need!

Medically reviewed in January 2019.

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