BALTIMORE — A cup of joe or a short nap can fend off normal afternoon sleepiness, but sleeping longer in the morning won’t keep a person who’s already gotten a full night’s sleep alert, a new study shows.
Researchers from the Sleep Research Center at Loughborough University in England tested 20 healthy young adults for daytime sleepiness. All of the volunteers got about 7.4 hours of sleep per night, and none of them complained of feeling sleepy. But when researchers put them in a quiet room and asked them to close their eyes — something the volunteers were asked to do several times in the afternoon and evening — all fell asleep within five to 10 minutes in the afternoon, indicating sleepiness. It took longer for the people to fall asleep when tested at other times, indicating that while they were drowsy in the afternoon, the people weren’t generally fatigued.
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