How Your Smartphone May Be Keeping You Up at Night

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I struggled with sleep deprivation while I was in graduate school. Even though I did not take medication to help me sleep, many colleagues and family members took sleeping pills because they could not get a good night’s rest. Research shows that up to 60 percent of all students nationwide suffer from poor sleep quality. While there are many potential physiological causes for this problem, there is something that we poor sleepers likely have in common: smartphones.

The blue light emitted from smartphones influences sleep patterns. Blue light is the shortest and brightest wavelength of light. This means that it can intensely penetrate our photoreceptors—the light-sensitive nerve cells in the eye’s retina. This is the part of the eye that relays light signals to the brain. When the brain senses blue light from a smartphone, it sees it as sunlight and thinks it’s daytime.

Minkyung Lee and Yonggeun Hong, DVM, PhD, at Inje University in South Korea, looked at the effects of smartphone light on sleep patterns, physiology and cognitive function. Lee and Hong presented their research at the Experimental Biology conference in April in Orlando, Fla.

The researchers divided adult volunteers into three groups according to smartphone screen brightness: 50 percent, 100 percent and blue-light filter. The volunteers used their phones for 10 minutes each during the day and at night. After daytime use, the people in the 50 percent group had much more autonomic nervous system (ANS) activity. The ANS regulates bodily functions such as heart rate, digestion and respiratory rate. Increased ANS activity is common after exercise, after drinking caffeinated beverages or when you’re stressed out—not when you are trying to wind down and go to sleep. In the night trial, however, the blue-light filter group showed better results in the language memory test, which suggests that smartphone light may influence memory and cognitive functions.

So what can we do to resist the urge to stare at our phones all night? Luckily, there are ways to limit the amount of blue light phones put out. Most devices have a night-shift feature that changes the screen from blue to yellow light. Yellow light has a longer wavelength than blue light and is less likely to keep you up at night. Also, you can download an app that reduces blue light. Or, the solution could be as simple as not using your smartphone 30 to 60 minutes before going to sleep.

I have to admit that after trying these methods, my sleep quality has greatly improved. Sweet dreams!

Nathalie FuentesNathalie Fuentes has a PhD in biomedical sciences from Penn State College of Medicine. She is a postdoctoral trainee at the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. Her dissertation focused on the development of sex-specific therapies to treat lung diseases, sex differences in asthma-related lung inflammation triggered by ground-level ozone and the role of male and female sex hormones in lung disease. She is originally from Caguas, Puerto Rico.

Nathalie served as a meeting blogger for Experimental Biology 2019.

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