Blue Light and Sleep: What's The Connection?

You may have heard that you shouldn’t play on your phone or watch TV before bed, but do you actually know why? It’s because of the blue light that these devices emit, which can mess with your circadian rhythm and make it difficult to fall asleep.

Learn more about how blue light and sleep are connected, as well as what you can do to make sure you’re getting a full eight hours of restful sleep every night. It is necessary for your health and well-being that you follow your internal circadian clock and establish a consistent sleep cycle. 

What Is Blue Light?

While we perceive light in terms of brightness, it can also be defined in terms of color — think of the rainbow. One of the colors that make up the spectrum of light is blue, and it has a shorter wavelength (and, as a result, more energy) than the other colors on the visible light spectrum.

Because of the way our eyes function, they are particularly susceptible to blue wavelength light. While our eyes might naturally block out red or yellow light waves, nearly all waves of visible blue light reach the retina or the part of the eye that processes light information.

You might be thinking — isn’t this good? Doesn’t this mean we can see better? Yes and no. Blue light is essential during the day because it regulates our circadian rhythm, which is what tells our body when it’s time to sleep and when it’s time to be awake. Processing enough blue light during the day will help you stay awake, enable alertness, and maintain a positive mood.

And since blue light is so important to have during the day, you can see why it’s something we don’t want to have at night. Why is blue light bad?  Given that blue wavelength light can affect night shift capabilities for our eyes, it’s best to limit the exposure before you sleep.

Ways You Could Be Exposed to Blue Light Before Bed

Your phone and TV are two big sources of blue light. Other electronic devices with a screen can also contribute to blue light exposure, like tablets, e-readers, or laptops.

One blue light source you may not know about, though, is LED lights. In the rush to become energy efficient, many homes ditched traditional bulbs in place of these less wasteful light sources. Unfortunately, this means our homes are often filled with more blue light than ever before. Even if you do avoid screen time at least two hours before bed, as research suggests, you may still find yourself tossing and turning once it’s time to lie down. The presence of blue light at night can ultimately affect your ability to fall asleep and stay asleep.

How Blue Light Affects Sleep

As you may have guessed, research suggests that exposure to blue light before bed can drastically disrupt your sleep patterns and sleep-wake cycle, making you feel more tired and less alert. One particular study took a look at two groups of people: those who read on an electronic device before bed and those who read from a traditional book before bed. The results showed that the electronic device group experienced “biological effects that may perpetuate sleep deficiency and disrupt circadian rhythms, both of which can have adverse impacts on performance, health, and safety.”

What exactly were these sleep disruptions? It turns out the electronic device participants had shorter REM sleep, which is the deepest stage of sleep in which the brain organizes memories and clears the slate, so to speak. While both groups slept for the same amount of time, the electronic device group had a much lower quality of sleep, making them feel more sluggish the next day.

Scientists don’t know for sure, but they attribute these side effects to a disruption in melatonin production. Melatonin is an essential hormone that signals when it’s time to sleep. Usually, as your body starts winding down for bed, this is because your melatonin levels are rising. They will stay elevated throughout the night to keep you sleepy and then drop back off in the morning to help you wake up. Unfortunately, research shows that blue light is the strongest light-based suppressor of melatonin, which is why it can be so disruptive to your sleep-wake cycle.

New Research Challenges Blue Light’s Effect on Sleep

Blue light and sleep: what’s the connection? Some new research is slightly changing the way scientists think about how blue light affects sleep. In one study, scientists exposed mice to different color lights to see their response. Surprisingly, yellow-toned light was found to be the most disruptive to sleep, not blue. They hypothesized that yellow light may be more associated with daytime, while blue light is more common at twilight.

However, since the studies were done on mice and not humans, scientists haven't scrapped the idea that blue light is the most disruptive to your sleep. Mice have very different eyes than humans, especially when it comes to the cone cells that allow us to distinguish between different wavelengths. Humans have three kinds of cones that allow us to see a wider spectrum of light than mice, which only have two. This study specifically analyzed how cone cells processed color, which doesn’t directly correlate with how humans process color.

Furthermore, mice are naturally nocturnal, meaning that they probably have a very different response to light than humans. What signals us to start winding down at night might be the sign for them to start gearing up.

Dr. Cathy Goldstein, a sleep specialist at Michigan Medicine, agrees with this viewpoint, telling Time magazine that “for this to get extrapolated to saying ‘blue light at night isn’t bad for you’ is a little bit of an extension.”

How to Reduce Blue Light Exposure and Improve Your Sleep

As you can see, blue light and sleep have a complex relationship, so it’s a good idea to limit your exposure if you want to get the most out of your nightly routine. That’s easy to do when you wear a pair of Blue Wave Glasses. These stylish frames were designed specifically to block out the blue-toned waves that can disrupt your natural circadian rhythm. Wear them throughout the day or as you’re gearing up for bed to enjoy a 60% reduction in blue light, all without distorting your vision.

Of course, blue light isn’t the only component to a good night’s rest. Other tips for regulating your sleep include keeping your room dark, going to bed and waking up at the same time every day, and even setting the temperature to around 60 to 68 degrees Fahrenheit. The Pod by Eight Sleep works with your individual needs to set the ideal surface temperature of your bed for both falling asleep and waking up with the Thermal Alarm. To ensure a good night's sleep, you'll want to be as cozy as possible, which is why we offer numerous sleep fitness accessories to improve your comfort and sleep quality all night long.

By taking all of these steps, you’re sure to overcome the pitfalls of blue light and get the quality sleep you deserve.