By Colin Allen, published on June 1, 2003 - last reviewed on June 16, 2009
Going without a full night's sleep is never ideal. But if it's necessary, sleep researchers say it's best to get rest in the early hours of the morning, rather than late at night. A new study found that while people's reactions to sleep deprivation vary widely, participants in the study group adapted better to sleeping in the morning.
The small study involved eight men ages 18 to 25. The participants were monitored as they slept a full eight and a half hours for the first two days. The next week, researchers divided the group in half. One group slept from 10:30 to 2:30 in the morning, and the other slept from 2:15 to 6:15.
Both groups functioned worse with sleep deprivation, but the early morning sleepers faired better in cognitive tests, such as a memory and driving. They spent more time sleeping in their four-hour window—what researchers call sleep efficiency—and fell asleep faster than late-night sleepers.
Lead author Christian Guilleminault, M.D., professor of psychiatry and behavioral sciences at Stanford University Medical Center, notes that people's reactions to sleep deprivation varied widely. One participant did not feel the impact of sleep deprivation until the fifth day, while another reacted so poorly to lack of sleep that he developed insomnia.
Guilleminault cautions that his study should not be taken as an excuse to sleep less, especially considering the varied reactions to less bed time.