The science: Light from our electronic devices is short-wavelength enriched, which means that it has a high concentration of blue light. Blue light adversely affects production of the sleep producing hormone melatonin more than any other wavelength. A 2015 study examined the effects of reading on a light-emitting device (such as a cell phone) compared with reading on a printed book. Participants who read on light-emitting devices took longer to fall asleep, had less REM sleep (the phase in which we dream) and had higher alertness before bedtime. Researchers also found that after an eight-hour sleep episode, those who read on the light-emitting device were sleepier and took longer to wake up (Chang et al., 2015).
What you can do: Put the electronic devices away 2 hours before bed. Instead, try reading a paperback book with dim environmental lighting. Another alternative is to wear blue wavelength-blocking glasses. Researchers have found that people wearing blue wavelength-blocking glasses for 3 hours prior to bedtime experienced a significant improvement in sleep quality and mood (Kimberly & James, 2009).