A recently published study in The Proceedings of the National Academy of Sciencessuggested that reading on an iPad or tablet before bed seem to make it harder to fall asleep. For the study, 12 subjects each read books either in paper form or on an iPad for four hours a night, five nights in a row. The next week they switched to the other format and did the same thing for next five nights.

Subjects who read on an iPad had a harder time falling asleep, spent less time in REM sleep, and reported feeling more tired the next day. The authors of the report hypothesize that the low-wavelength blue light emitted from the digital readers inhibited the release of the hormone melatonin which, in turn, lead to less sleepy-time.

Melatonin is a naturally occurring hormone that your body synthesizes from tryptophan—the amino acid in turkey that is supposedly responsible for that post-Thanksgiving food coma many Americans know all too well. (FYI, chicken has higher levels of tryptophan than turkey, so the post-turkey sleepiness people feel is probably just a sugar crash).

Scientists have mapped in detail how the human body transforms tryptophan into melatonin: it requires an enzyme called AANAT, and the gene responsible for making AANAT is deactivated when exposed to light. There is evidence connected suppression of melatonin production with higher rates of breast cancer, colorectal cancer, and prostate cancer. So using a tablet before bed could have bigger impacts than just grogginess the next day.

One important point that the author of the study points out however is that the subjects only used an ipad, at full brightness. They didn’t examine other front-lit devices, and it’s possible just lowering the brightness could curtail these potentially negative effects.

Have you noticed any trouble sleeping after reading on a table before bed? Have you noticed any other strange symptoms when using your iPad or e-reader? Please share in the comments section below.
“A new study has claimed that light-emitting e-readers ‘negatively affect sleep, circadian timing and next-morning alertness’ when used in the evening. However, those reading the resulting coverage should look into the details before worrying too much.”
“Use of a light-emitting electronic device (LE-eBook) in the hours before bedtime can adversely impact overall health, alertness, and the circadian clock which synchronizes the daily rhythm of sleep to external environmental time cues, according to researchers at Brigham and Women’s Hospital (BWH) who compared the biological effects of reading an LE-eBook compared to a printed book.”