TRIVIA – Reading from a tablet before bed may affect sleep quality
Reading from a tablet before bed may affect sleep quality
People who read from an iPad for 30 minutes before going to sleep felt less sleepy and had different electrical activity in the brain during sleep than those who read from a physical book, a recent study found.
But the time it took to fall asleep and time spent sleeping were similar under both conditions.
“Since light has an alerting effect, we predicted a lower sleepiness in the iPad condition at bedtime compared to the book condition,” said lead author Janne Gronli of the University of Bergen in Norway. But it was surprising that the iPad light did not delay sleep initiation, she said.
The study included 16 nonsmokers ages 22 to 33 who were familiar with tablets and had no sleep, medical or psychiatric disorders. For a week before the study began, they were instructed to keep to a regular sleep-wake schedule and to stay in bed at least as long as they needed to sleep.
During the study, in which participants slept in their own beds, the researchers took polysomnographic recordings for three nights of sleep: one to collect a baseline of how each person slept, one night of reading from an iPad for 30 minutes before turning out the light and one night of reading from a book for the same amount of time.
On the night they read from a book, the participants used ordinary reading light in their bedrooms.
Bedtime and the time at which people got up from bed were similar in both conditions, with an average sleep duration of slightly less than eight hours on both days.
Participants said they felt sleepier when reading the physical book, as reported in Sleep Medicine. After reading from an iPad, EEG readings showed delayed and reduced slow wave activity, representing deep sleep, in the brain after sleep onset compared to when the participants had been reading from a book.
The eye absorbs short wavelength blue light and signals to the brain that it is daytime by triggering waking and alerting active brain areas, Gronli said.
“The brain’s ability to synchronize cortical activity and generate slow waves with high amplitude when we sleep improves memory and cognitive performance, she said.
“The effects are not completely huge,” Samer Hattar of Johns Hopkins University in Baltimore told Reuters Health.
And since the researchers only measured illumination, they could not compare the “structure” of the iPad light to regular bedroom light, Hattar said. Some indoor light bulbs also emit a great deal of blue light while others do not.
“We only examined one night using an iPad,” Gronli said. “It is tempting to speculate that daily use of an iPad, and other blue light emitting electronic devices, before bedtime may have consequences for human sleep and cognitive performance.”
“To avoid increased activation before bedtime the bedroom should be used to sleep in, not for work or being on social media,” she said.
