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.
