Those Tablets Are Bedtime’s Worst Enemy

A recent study done by Brigham and Women’s Hospital in Boston shows that reading on electronic devices before going to bed can have particularly deleterious effects on your night’s sleep. This is because these devices emit blue light directly into your eyes, retarding melatonin production. And melatonin is the sleep hormone that helps you get to sleep and stay asleep.

The direct emission of short-wavelength enriched light “is exactly what you don’t want to do at bedtime,” according to Charles Czeisler, the study’s senior author and chief of the hospital’s division of sleep and circadian disorders.

“Many people read things to help them fall asleep. They probably don’t realize that this technology is actually making them less likely to feel sleepy,” Czeisler adds.

The study involved 12 healthy adults who spent two weeks in the sleep lab at the hospital. The group was split into two, each reading four hours each night before retiring. One half would read physical books; the others would read on e-readers.  Halfway through, the two groups switched reading styles. Beddy-bye was enforced at 10 p.m.

Those who read their books on iPads (the only e-reader allowed) took 10 minutes longer to fall asleep and showed less rapid eye movement (REM) sleep when monitored throughout the night. Tests also confirmed that their lessened melatonin production set their circadian rhythms off by one hour.

(In separate tests the researchers found that iPhones, iPods, the Nook Color and the Kindle Fire all had similar short-wavelength emissions.)

Dr. Czeisler is now planning a second test, for which no bedtime will be enforced. He said he expects the results to be even more dramatic.

If you do like to read before sleep, a book — with no blue light emissions — is your best choice. Otherwise, you can try wearing blue-light-blocking glasses, which tend to give everything a yellow tint.

If after following this and other good sleep-hygiene principles, you still have difficulty going to sleep and/or staying asleep, then it’s time to seek professional help, starting with your family physician and then escalating to sleep doctors for the ultimate resolution.

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