More Research on the Negative Effects of Using E-Readers before Going to Sleep


A new study from Brigham and Women's Hospital (BWH) has discovered more information about how reading on screens before bed is causing sleep and health problems.

This blog was orginally written by Beth Taylor for

"We found the body's natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices," said study author Anne-Marie Chang, PhD, an associate neuroscientist in BWH's Division of Sleep and Circadian Disorders. "Participants reading [light-emitting electronic device] eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock and reduced next-morning alertness than when reading a printed book."

What You Read on Matters

Reading a book made from paper before bed does not destroy your sleep cycle and circadian rhythms. The study at BWH indicates that reading on a device that emits blue light, however, does impact your ability to sleep well.

Devices that emit blue light include computers, laptops, ipads, tablets, and e-readers and smartphones.

Blue Light

"Blue light" is just that -- the wavelengths of light that appear blue to the human eye. During the day, blue light is advantageous. It boosts our mood, our attention span, and even our reaction times.

Blue light at night, however, is detrimental. The blue light emitted from our screens tells our bodies that it is the middle of the day. The body responds by not producing the melatonin we naturally generate in the evening. Melatonin is a natural hormone that causes relaxation and prepares the body and mind for sleep. Harvard Medical School is careful to point out that any type of light at night is harmful to the sleep cycle, but blue light has a stronger effect and is most detrimental to our circadian rhythms.

Sleep Deprivation

If you don't get enough sleep, you will at best feel sluggish and grumpy. You are also more likely to have an accident, use poor judgment, or develop physical problems such as high blood pressure.

In 2007, psychologist Matthew Walker took functional magnetic resonance imaging (fMRI) pictures of brains of sleep-deprived study participants. The results were profound; sleep-deprived participants had highly charged responses to stimuli in their amygdalas. This mimics the emotional reactions of some types of mental disturbances.

What You Can Do

It's not all bad news. Try these suggestions to help yourself get everything done during the day and get the sleep you need at night:

  •     Read a paper book instead of an e-reader;
  •     Print out documents and PDFs at work if you need to read them in the evening. This way, you can read them on paper; or
  •     Purchase a blue light filter for your device. Sweet dreams!

Source: Beth Taylor, 2015. "Reading on a Computer Screen Before Bed Is Killing Your Productivity". PayScale, Jan 23.