Hoping to get a good night’s sleep? You might want to grab a book instead of your smartphone when you get into bed tonight.
A new study by researchers at the University of Houston (UH) College of Optometry finds that the blue light emitted from digital devices decreases sleep quality and may be contributing to the high prevalence of reported sleep dysfunction.
For two weeks, study participants aged 17-42 put on short wavelength-blocking glasses three hours before bedtime, while still performing their nightly digital routine. This practice resulted in a 58 percent increase in their nighttime levels of melatonin, the chemical that signals your body that it’s time to sleep.
In fact, the nighttime increases of melatonin due to wearing the glasses prior to bedtime were even higher than those from over-the-counter melatonin supplements, according to Dr. Lisa Ostrin, the UH College of Optometry assistant professor who lead the study.
“The most important takeaway is that blue light at night time really does decrease sleep quality. Sleep is very important for the regeneration of many functions in our body,” said Ostrin.
While wearing activity and sleep monitors 24 hours a day, the 22 study participants also reported sleeping better, falling asleep faster, and even increased their sleep duration by 24 minutes a night, according to Ostrin.
The largest source of blue light is sunlight, but it’s also found in most LED-based devices. Blue light raises our level of alertness and regulates our internal body clock, or circadian rhythm, that tells our bodies when it’s time to sleep. This artificial light activates photoreceptors called intrinsically photosensitive retinal ganglion cells (ipRGCs), which suppresses melatonin.
Before bedtime, Ostrin recommends limiting screen time, applying screen filters, wearing computer glasses that block blue light, or using anti-reflective lenses to offset the effects of artificial light. Some devices even include night mode settings that limit blue light exposure.
“By using blue-blocking glasses we are decreasing input to the photoreceptors, so we can improve sleep and still continue to use our devices. That’s nice, because we can still be productive at night,” Ostrin said.
More than four in 10 Americans reported that their daily activities were significantly impacted by poor or insufficient sleep at least once during the past seven days, according to the most recent findings from the National Sleep Foundation’s Sleep Health Index.
The findings are published in the journal Ophthalmic & Physiological Optics.
Source: University of Houston