Seems that none of my patients sleeps, or at least not very well. Indeed, population-based studies suggest that almost one-third of adults report difficulty initiating or maintaining sleep, waking up too early, and/or nonrestorative or poor quality of sleep.
Light-emitting electronic “e-readers” or “e-books” have exploded as a favorite medium for reading. Many of my patients tell me that when they are unable to sleep, they read. Much of this reading occurs on e-books. But artificial light can produce alerting effects and suppress melatonin. This might be causing or worsening the national insomnia epidemic.
Dr. Anne-Marie Chang and colleagues conducted a randomized, crossover study evaluating the impact of an e-book and a traditional book on sleep ( PNAS 2014 Dec. 22 [doi:10.1073/pnas.1418490112] ). In the study, 12 healthy young adults were randomized to two conditions: 1) reading an e-book for 4 hours before bedtime; or 2) reading a printed book for 4 hours before bedtime on 5 consecutive evenings. Participants then switched conditions.
The e-book suppressed evening levels of melatonin by 55%, whereas the printed book showed no suppression, and the e-book shifted the melatonin onset to more than 1.5 hours later. Compared with the printed book, the e-book also significantly increased sleep latency (10 minutes longer), decreased REM sleep by11 minutes, decreased evening sleepiness, and increased morning sleepiness.
But not all e-book readers are created equal. Screens of devices used in the current study emit blue light (wavelength 452 nm), the type of light most implicated in melatonin suppression. Newer “e-ink” readers do not emit this light and are “front lit,” with light cast inward rather than outward.
People struggling with insomnia should be encouraged to explore the e-ink options. The table included in the study can provide some guidance as to the type of e-book that may be most beneficial to our sleepy patients.
Dr. Ebbert is professor of medicine, a general internist at the Mayo Clinic in Rochester, Minn., and a diplomate of the American Board of Addiction Medicine. The opinions expressed are those of the author. The opinions expressed in this article should not be used to diagnose or treat any medical condition nor should they be used as a substitute for medical advice from a qualified, board-certified practicing clinician.
