College and university students, who already prefer to study from printed pages rather than digital, may have yet another reason to stick with paper textbooks. A study recently published in the Proceedings of the National Academy of Sciences found that sustained reading from a tablet or e-reader right before going to bed can disrupt sleep and diminish mental capacity the following morning.
The study group was small—just 12 students—and involved reading for four hours in a dimly lit room prior to bedtime, first with e-books for five nights and then with printed books for five nights. Then the participants switched the order for the next 10 nights.
On average, after reading the e-books, the students took about 10 more minutes to fall asleep and felt more drowsy in the morning. Researchers concluded that the light emitted by many tablets and e-readers delayed production of melatonin in the brain by more than 90 minutes. Production of the hormone peaks during sleep.
The concern, according to the research report, is not just the cumulative impact on readers’ sleep and alertness. Ongoing suppression of melatonin production has been linked to cancer and other serious illnesses.
The report noted students could reduce the negative effects by limiting the use of light-emitting devices at night, including phones and computer monitors, or using only devices that don’t put out light.