Reading before bedtime is long believed to make sleep easy, but it might be best to avoid doing so from light-emitting screens, according to a new study from Pennsylvania State University.
Exposure to light before going to sleep reduces the hormone melatonin, which controls the biology clock, making it harder to fall asleep.
Working with a small participant group of 12 adults, Anne-Marie Chang, an assistant professor, and her team compared how long it took them to fall asleep reading books downloaded onto an iPad with reading books from the bookstore or library.
In the two-week study, participants slept at Brigham and Women’s Hospital in Boston under the observation of the research team, who also monitored their melatonin levels, how long they slept and their alertness in the morning.
As they drifted off, participants read from 6pm to 10pm from an iPad for five consecutive nights and then switched to print for another five nights in a row using the same timeframe.
Those who read from the iPads took 10 minutes longer to fall asleep than those who read from print and their sleep was lighter, indicated by data that measured considerably less rapid eye movement (REM) sleep from the iPad readers than it did for the print readers.
“Our most surprising finding was that individuals using the e-reader would be more tired and take longer to become alert the next morning,” says Chang. “This has real consequences for daytime functioning, and these effects might be worse in the real world.”
The Kindle e-reader could be an exception, for it emits no light, according to the research team, who measured the amount of brightness emitted by the iPad, iPhone, Kindle, Kindle Fire and Nook Color.
All other devices emitted roughly the same amount of light, with the iPad topping the brightness list.
Chang, whose study was published in Proceedings of the National Academy of Science, says further research is necessary in light of terrible sleep statistics in modern society.
本时文内容由奇速英语国际教育研究院原创编写，禁止复制和任何商业用途，版权所有，侵权必究！
13980503458
13980503458
admin@qisuen.cn
