Study finds early morning is best for limited sleep

Just how restful four hours of sleep is seems to depend on the time of night you get it. Stanford University Medical Center researchers have found that men who didn’t turn in until almost morning slept better than those who went to bed early.

Eight participants, age 18 to 25, spent more than a week in a sleep lab, having their sleep monitored and taking various tests of their wakefulness. After two days of sleeping normally for about eight hours, their sleep was restricted to four hours a night. One group slept from 10:30 p.m. to 2:30 a.m. The other group slept from 2:15 a.m. to 6:15 a.m.

The early-to-bed group scored low on tests of daytime wakefulness after just one night of sleep restriction. The late-to-bed group didn’t begin to nod off during daytime studies until nearly the end of the experiment. (On day five, for instance, men in that group scored borderline-normal on wakefulness tests.)

Both groups had a decrease in leptin, a hormone associated with appetite. And they all ate more in the days when they were sleep deprived. “Sleep restriction changes brain control of appetite,” said lead author Dr. Christian Guilleminault, a professor of sleep medicine at Stanford University School of Medicine.

The study was published in the May issue of Sleep Medicine.

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-- Diane Partie Lange