eReaders sabotage your sleep

Posted on Tue, 10 Feb 15

A recent study found that, compared to a book, a light-emitting eReader suppresses melatonin, impairs your sleep and reduces next day alertness.

About 90% of Americans report using electronic devices regularly within 1 hour before bedtime. Light-emitting devices such as computers, televisions, tablets, mobile phones and eReaders could disrupt you natural sleep pattern by exposing your eyes to artificial light, which is known to supress production of the sleep hormone melatonin.

Researchers recently compared the biological effects of reading a printed book to a light-emitting eBook before bed. In the experiment, twelve healthy young adults read an eBook before bedtime for five consecutive evenings, and then switched to a printed book or vise versa.

When reading the eBook they took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness.

“The results of this study are of particular concern, given recent evidence linking chronic suppression of melatonin secretion by nocturnal light exposure with the increased risk of breast, colorectal, and advanced prostate cancer associated with night-shift work…” commented the study investigators.

“Moreover, the observation that the endogenous circadian melatonin phase was 1.5 hours later when reading an eBook compared with reading from a printed book suggests that using a light-emitting device in the hours before bedtime is likely to increase the risk of delayed sleep-phase disorder and sleep onset insomnia...” they said.

Reference:

Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness.  Proc Natl Acad Sci U S A. 2015 Jan 27;112(4):1232-7.