Your body moves to its own rhythm — circadian rhythm, that is. This is your body’s innate, internal clock that typically follows a 24-hour cycle based on the sun, and controls many of the physical and chemical processes in your body. 

Your circadian rhythm is generally hardwired, but can be influenced by certain factors — including exposure to blue light. Here, learn more about blue light, how blue light impacts your sleep, and how to mitigate the effects. 

What Is Blue Light?

Blue light includes any visible light with a wavelength between 400 and 450 nanometers (nm). These short, high-energy waves are very powerful — only slightly less powerful than damaging UV rays. While blue light may be perceived as “blue” in color, it can also appear as white or any other color to the human eye. 

Sunlight naturally contains blue light, as do fluorescent and incandescent lights. Plus, the technological devices we use today have much higher amounts of blue light than the sun. (You’re probably reading this on a blue light-emitting device right now!) Blue light can be found in any light-emitting diode (LED) device, including computer screens, flat-screen TVs, smartphones, and tablets.

While blue light, both natural and man-made, can be beneficial during the day to boost energy, attention, and focus, it has been shown to disrupt your circadian rhythm — and as a result, your sleep — at night. Today, thanks to technology, humans are exposed to more blue light today than ever before. This can lead to disruptions in our sleep — and potentially our overall health as a result. 

How Blue Light Impacts Your Sleep

Your eyes have special receptors called “photoreceptors” that constantly track the amount of light in your environment. When your eyes register that the environment around you is dark, it sends a signal to your brain’s time-keeping center, the suprachiasmatic nucleus, or SCN. 

Once the SCN receives that signal, it prompts the tiny pineal gland to release melatonin, the hormone that makes you sleepy and also lowers your core body temperature. (Melatonin is also sometimes called the “vampire hormone” or the “Dracula hormone” — not because it’s sinister, but because it only comes out at night.) 

In the days before electricity, your eyes would sense darkness at the appropriate time, usually a few hours after dusk, around 9 pm. At that time, your brain would release melatonin, and you’d get sleepy. Melatonin levels are typically elevated for about 12 hours, until they decrease again by around 9 am. During the daytime, melatonin levels are undetectable.

However, the invention of electricity — and more recently, our always-on devices — changed all of that. Artificial evening light fools your eyes into thinking that the sun has not yet set. As a result, our SCN doesn’t realize it’s nighttime, and won’t signal the pineal gland to release melatonin. In other words, your cell phone, tablet, computer, TV, and even your bedside lamp all put a hard stop on your ability to get sleepy.

What’s more: Blue light has been shown to be particularly harmful to melatonin production. According to one study, blue light seems to suppress the release of melatonin by over 50%. Another study found that reading before bed from a blue light-emitting tablet (compared to a printed book) can even change your sleep quantity and quality, determining that people felt less rested and sleepier the following day. (Kind of like a blue-light hangover.) 

How to Limit Blue Light Exposure

The best way to prevent blue light from wrecking your sleep is to be conscious of limiting your exposure after the sun goes down — especially before bed. But there are other ways to curb the negative effects of blue-light tech. 

Try one or more of the below hacks and you may find yourself falling asleep faster or boosting the amount of deep sleep you get each night. On the Oura App, Use the “Blue light blockers” tag to start noticing trends and seeing the potential benefits of blue-light-blocking tech on your sleep. 

  • Wear blue light-blocking glasses: Blue light-blocking glasses, such as those by Ra Optics, are scientifically backed and are a complementary tool to other blue-light-blocking technologies. These will block any lingering blue light from electronic devices and most home lighting.
  • Purchase a blue light-blocking screen filter: Blue light-blocking filters, which adhere to the screen of your device, are available for almost any computer, tablet, or smartphone. Research shows these are effective at eliminating much of the device’s blue light emission. 
  • Install special software and/or apps: Apple iOS (Night Shift) and Android OS (Night Light) allow you to set a schedule for reducing the amount of blue light your device emits. Similarly, some computers support the application Flux, which also lets you schedule blue light reduction.
  • Swap out your lighting: Special light bulbs can reduce or eliminate blue light as well. Two examples of these bulbs are the Philips Hue and the Lighting Science GoodNight Biological LED Lamp.