It's 10pm—or maybe it’s 2am—doesn’t matter. You can’t sleep. Whether you've been tossing and turning since you crawled into bed or dozed off earlier only to find yourself wide awake now, you're frustrated and worried about how you'll get going in the morning. Or maybe you actually did manage to get to doze off right away, yet the next day you're inexplicably exhausted. What gives?
While there are a whole host of reasons (stress, perimenopause, the cappuccino you had after dinner) for not getting good quality rest, there's one that probably hasn't crossed your mind: Blue light.
Blue light, explains Northwell Health sleep specialist Preethi Rajan, MD, is a type of light with a wavelength in a specific part of the light spectrum. It doesn't look blue to the naked eye—it looks like a white glow—and it's what's coming out of your smartphone, iPad, laptop, e-reader, and practically every other electronic device in your house. You'll also find it in fluorescent and LED light bulbs.
"It's particularly stimulating to the circadian system, your body's internal clock that tells you when to feel sleepy and when to perk up,” Dr. Rajan explains. It also regulates other physiological functions, like hunger.
External signals, like sunlight, are supposed to keep your body clock ticking along. Humans are naturally designed to rise as the sun comes up and rest when it gets dark out, but since the advent of the light bulb, that's rarely what happens anymore.