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by Ashley Yeager
Screen time before bedtime may leave people feeling groggy in the morning. Cell phones, computers, and TVs emit blue light. And exposure to that bluish light during the two hours before bed can keep us from getting a good night's rest, a new study finds. It cuts down the number of minutes people slept. It also left them feeling groggy in the morning.
It's been known for quite a while that "blue light is bad for sleep," observes Shadab Rahman. He was not involved in the new study. His work sleep at Brigham and Women's Hospital in Boston, Mass. does, however, study how light affects the body's internal "clock." Its natural cycles tell us when to sleep and when to get up in the morning. These cycles are known as our rhythms. The light of day and the dark of night both work to help keep this internal clock running on a roughly 24-hour cycle
Computers, televisions, tablets, and other electronic devices give off all colors of light. And, he notes, evidence has been emerging that these screens—and especially the blue light they give off—can disrupt the body's clock. Data show that this blue light tends to make us more alert at night. That makes it harder to fall asleep and get all the rest we need.
Because electronic devices are all around us, it's hard to avoid their blue light. We use the screens constantly, notes Amit Shai Green. He is a Ph.D student at the University of Haifa in Israel. He also is an author of the new study.
Green and his team recruited 19 people—all in their 20s—for a sleep study. All spent two hours on a computer right before bedtime. But they didn't all experience the same light exposures.
The researchers had tweaked the computer screens. Some gave off intense blue light. Others gave off soft blue light, intense red light, or soft red light. Red light hasn't been shown to affect sleep the way blue light does. For the new experiment, the researchers used red light as a control against which to compare any effects on sleep of blue light.
While the recruits slept, the researchers recorded how many times the participants woke up throughout the night and how long they slept overall. The scientists also charted when each person was in a phase of sleep known as REM (short for rapid eye movement). This is the stage when dreaming occurs. Lastly, each recruit reported how rested he or she felt the next morning.
Looking at screens that gave off intense blue light cut someone's sleep by about 16 minutes, compared to when they had used screens with red light. Those exposed to blue light also woke up more often at night than if they had been exposed to red light.
Rahman recommends powering down electronics two hours before going to sleep. He says, read a book instead, talk with your family and friends, or write in a journal.
If you have to do homework before bed, he says, dim the screen and the lights. Making it darker can help you wind down. If you drift off, maybe it's because you need the rest. And you never know—maybe the answer to that final algebra problem will come to you in your sleep.
2
Which of the following can the reader infer from the passage?
A.
The results of the study show that electronics have a negative impact on people’s health and more needs to be done to reduce the harmful effects.
B.
The results of the study prove that people are reckless in their use of electronics before falling asleep due to their lack of understanding.
C.
The results of the study remind people to think twice about how they use screens before bed since it is inevitable that people will use electronics.
D.
The results of the study reveal that there was not enough reliable information to fully determine whether electronics always affect sleep.
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