We’ve all heard it a thousand times –– the blue light from screens is bad for sleep. Blue light suppresses your body’s natural influx of melatonin when the sun goes down, meaning you’re tricking your brain into thinking it’s still time to stay awake. 

As a way to solve this problem (and enable us to scroll through social media), there’s a setting on your phone that allows you to turn on a blue light filter. When you turn it on, your screen will appear to have a yellow tint. But don’t worry, you get used to it surprisingly fast. 

“Blue light filter settings on digital devices work to reduce the amount of blue light emitted by adding a warm, yellow tint to the screen. While some people have this on at all times to reduce eye strain, others only use it in the evenings to reduce their blue light exposure before they go to sleep,” Says Dr. Bonsung Kim, optometrist at Della Optique Optometry and Eyewear.

Blue light filters are a solution to a problem and are supposed to help us sleep better. However, the yellow tint of the filter may be having unintended consequences. Here’s how. 

Do Blue Light Filters Actually Work?

Yes. Blue light filters do exactly what they advertise. They cut out the blue light that our screens emit. They are designed to reduce melanopsin –– the protein in the eye that responds to light intensity and plays a part in regulating your body’s clock. 

Given the negative effects of blue light –– trouble sleeping, headaches and eye strain –– blue light filters seem like a huge win. Despite the apparent benefits, there may be a dark side to blue light filters that no one expected. 

A study on mice from the University of Manchester found that the eye’s color-sensing cones were more responsive to yellow light, which means that the yellow tint of the filter may also be keeping you up at night. Their research suggests that it may even be worse than blue light. The team proposes that if the lights are equally dim, it’s more beneficial to use warmer lights in the daytime (to mimic the sun) and cooler lights (like twilight) during the evening. 

Another study published in Optometry and Vision Science concluded that blue light filters are not an effective way to treat digital eye strain. Even though these filters block out the blue light, it seems they are causing some of the same issues they aim to solve. 

What Does This Mean For You?

In the end, blue light filters do work. They can even save you from some of the adverse side effects that blue light causes. But research is suggesting that they are not the solution to helping you sleep at night. They can also trick your brain into thinking you should stay awake.

A good way to look at it is: if you turn on your blue light filter to help get ready for bed at night, you should just put down your phone. If you’re working towards getting better sleep, your best move is to completely cut your phone out of the equation. Try to turn off all screens at least 45 minutes before bed and focus on relaxing activities. 

Tips for falling asleep at night: