Can using a blue light filter improve sleep quality?

Scrolling through social media in bed can feel like the best use of your time when you can’t sleep, but did you know the light emanating from your device can also prevent you from falling asleep in the first place?

It’s true. Many devices with screens, as well as other sources of light like lamps, emit a range of blue light that suppresses your body’s natural production of melatonin. This is a hormone that regulates your sleep-wake cycle and circadian rhythm, which is your biological clock that guides various bodily functions like hormone release and internal temperature.

This is important because poor sleep is associated with a host of health conditions like:

• Heart disease
• Type 2 diabetes
• Depression
• Obesity
• Several types of cancer, including breast cancer, ovarian cancer, prostate cancer and melanoma

“There’s lots of evidence that poor-quality sleep, short sleep and sleep-apnea are cancer-related,” says Dave Balachandran, M.D., medical director of UT MD Anderson’s Sleep Center.

Blue light isn’t just a cell phone issue. It’s used by most TVs, computer screens, tablets and e-readers, fluorescent lights and LED lights.

Many phone manufacturers have responded by creating settings that filter out blue light with other kinds of light or dimming the background. Some sellers offer blue-light-blocking glasses and physical blue light filters that fit over your device’s screen.

But do any of them work?

Balachandran says there are no quick fixes here.

What is blue light, and why is blue light bad for sleep?

Blue light is any visible light with a wavelength between 400 and 450 nanometers (nm). It’s less powerful than UV rays.

“Sunlight contains blue light, and it's very important for maintaining our circadian rhythms,” Balachandran says.

The retinas in our eyes have special cells that are activated when they are exposed to blue light. When they are activated, they send a message to the brain that tells the pineal gland to cut off melatonin production.

“Melatonin helps us regulate sleep. It makes us sleepy,” he says. “When blue light activates those cells, it turns off that signal to produce melatonin very quickly. It’s almost instantaneous.”

Because of its ability to stop melatonin production, blue light is sometimes used to boost alertness, energy and mood. It’s also used to treat depression. It’s healthy to get outside during the day and get blue light exposure to stay awake and alert. But when you get exposed to it at night, you’re essentially tricking your brain that it’s daytime. This is known as a “phase delay.”

“A phase delay is a shift in your circadian rhythm that could last for that night, may last for a couple nights. Or if you get blue light all the time, it will persistently shift your circadian phase so that you will be more likely to fall asleep later and wake up later in the morning,” Balachandran adds.

Limiting blue light at night can help you get to sleep and stay asleep.

Can blue light filters improve sleep quality?

Many devices now have dimming modes or blue-light-blocking modes. But Balachandran says there’s not enough research to prove whether they work. The same is true for blue-light-blocking glasses and physical filters.

Let’s take a look at the available options.

Dimming or night mode on phones and tablets

These are meant to limit blue light and replace it with light at other frequencies.

“What research shows is that they help decrease the amount of blue light that hits the retina,” Balachandran says. Therefore, the blue light is less likely to stop the production of melatonin. “However, newer data suggests it may not just be the blue light that’s causing delayed sleep.”

He says the light’s intensity – no matter what kind of light it is – and the activity you're doing can also impact how tired you are and how well you sleep. So, the e-mail or book you’re reading, or the work you’re doing on a laptop, can stimulate your brain and cause a delay in falling asleep.

Balachandran calls these other factors “confounders” and says that they also affect the science behind physical filters and blue-light-blocking glasses.

“The research is very mixed,” he says. “I don't think there are any really strong studies here.”

Blue-light-blocking glasses for sleep

These glasses, which may look amber tinted, also block blue light from hitting your retina. But Balachandran says removing blue light may not be enough to help you fall or stay asleep.

“That’s because you're not getting rid of all those stimuli to wakefulness,” he says. “There’s no good data showing that wearing blue light glasses is effective in restoring your typical sleep patterns.”

Physical filter on your phone

The only difference between a phone filter and blue-light-blocking glasses is where the filter sits. There’s no research that recommends one over the other, Balachandran says, adding that the best strategy is to avoid screens around bedtime.

Proven ways to reduce blue light and get better sleep

The most effective way to limit your exposure to blue light before bed is to avoid all screens starting at least 30 minutes before bedtime.

Also consider turning off all LED lights at least an hour before bedtime, or using softer, amber-colored lights instead. And when you go to sleep, keep your bedroom completely dark with blackout curtains, or use an eye mask.

Removing sources of light at night is just one piece of the puzzle to getting more sleep, Balachandran says. It’s important to build healthy sleep hygiene. This includes:

• Using your bedroom only for sleep and sex, and not for work or entertainment
• Having a routine for mealtimes, work or school and socialization
• Avoiding daytime naps or limiting them to 20 minutes
• Avoiding caffeine after 12 p.m.
• Keeping your bedroom temperature cool and comfortable
• Wearing nighttime clothes made from breathable fabric
• Going to bed at the same time every day and waking up at the same time each morning
• Having a bedtime ritual that helps you fall asleep
• Trying a white noise machine

The last word on blue light filters

Balachandran says the best way to avoid all stimuli and fall asleep quickly is to be in bed with your eyes closed and avoid all distractions.

“I know we all kind of want simple solutions, but I don't think there is one in this case,” he says.

Request an appointment at UT MD Anderson online or call 1-877-632-6789.