4 Ways to Stop Blue Light From Ruining a Good Night's Sleep — and Your Circadian Rhythm

Blue light is processed by special photoreceptors in your eyes, which in turn stimulate different parts of your brain, said Mark Wu, MD, PhD, an associate professor of neurology at Johns Hopkins who specialises in sleep and circadian rhythm disorders. One affected area is called the suprachiasmatic nucleus (SCN), which is responsible for regulating your circadian rhythm, the internal clock that keeps you going to bed and waking up at the same times.

"If you expose yourself to blue light at night, what it can do is shift your clock later," Dr. Wu told POPSUGAR. "It would make you want to go to bed later and then wake up later, which obviously is not ideal for lots of working people." In other words, if you're habitually on your phone or laptop late at night, it can trick your body into thinking it's daytime, keeping you alert and awake when you'd usually start to get sleepy.

"Generally, this is not likely to happen after just one night," said Luis Buenaver, PhD, an assistant professor and director of the Behavioural Sleep Medicine Program at Johns Hopkins's department of psychiatry and behavioural sciences. "But [it] may become an issue after several nights or if it becomes a bad habit."

Relatedly, melatonin is a hormone that regulates your circadian rhythm. Blue light actually can neutralise the effects of your naturally-occurring melatonin, which is "usually secreted about two hours prior to one's habitual bedtime," Dr. Buenaver explained. Too much exposure to blue light can throw off that routine and keep your brain on high alert, making it difficult to fall asleep or sleep soundly once you do drift off.

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On top of disrupting your circadian rhythm and melatonin production, blue light also directly stimulates the part of your brain that makes you feel awake, Dr. Wu said. That can be a good thing during the day, but "it's not something you want when you're trying to go to bed," he explained.

That's especially important because, even beyond blue light, using your phone or computer before bed will naturally make you feel more alert. If you're reading or watching something that gets you worked up in some way, it's going to be hard to drift off. "You get either excited or upset, and that's not conducive to sleep," Dr. Wu said. When you put together that natural stimulation with the physical effects of blue light on your brain, hormones, and circadian rhythm, you get a combination that's highly likely to disrupt your sleep.

Dr. Wu and Dr. Buenaver suggested a few ways to deal with the sleep issues created by blue light. If you find yourself mindlessly scrolling Instagram or clicking yet another video as it gets closer to bedtime, try a few of these techniques to keep your sleep cycle on track:

• Enable your device's "night mode" function. Your phone or laptop's "night mode" or "dark mode" filters out the blue light from your screen. "It makes your screen look kind of orange-ish. Make sure to enable that," Dr. Wu said, if you're going to looking at your screen close to bedtime.
• Use blue light-filtering glasses. If your screen doesn't have a night mode function, both doctors said that blue light-filtering glasses work in the same way. Here are 10 blue light glasses you can try.
• Dim any ambient lighting. Since regular light exposure can also suppress melatonin, Dr. Wu recommended dimming your overhead lights more and more as you get closer to bedtime. This might mean moving from the well-lit living room to your darker bedroom, or switching from an overhead light to a smaller reading light. This can help bring your circadian rhythm back on track.
• Put down your phone or computer at least 30 minutes before bed. This is the hardest one, we know. "Everyone's always connected to their devices," Dr. Wu said. "But usually we recommend at least at least a 30-minute or one-hour wind-down period, if possible." Dr. Buenaver recommended trying for a two-hour window; more of a challenge, but something you could work your way up to in time.

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