According to a study, which will be published in the August 5 edition of Current Biology, healthy adults need less sleep as they age.

“Older people may simply need less sleep than younger people,” said study author Dr. Elizabeth Klerman, an assistant professor of medicine in the division of sleep medicine at Brigham and Women’s Hospital in Boston. "It could turn out to be that they have more trouble falling asleep. But it could also, in fact, be that they get what they need in less time. We just don't know the reason yet."

Klerman said the observation, if true, could mean that what elderly individuals may interpret as insomnia is actually a normal reflection of an age-related shift in their internal clock.

Klerman and her colleagues studied the sleep behaviors of 35 individuals between the ages of 18 and 32 and compared them with those of 18 individuals between the ages of 60 and 70.

All of the participants spent 16 hours a day in bed for three to seven days.

The younger group slept more during the study than they did during their normal routine, researchers found.

The older group slept an average of 1.5 hours per day less than the younger group, and it took them longer to fall asleep.

Dr. Gregg Jacobs, a sleep specialist with the Sleep Disorders Center at the University of Massachusetts Memorial Medical Center, described the study as “the best I’ve seen to date on the physiology of older people’s sleep.”

"This study addresses a real need, because most of the research on sleep debt is focused on college students, but most people with sleep issues are middle-aged and older adults," he observed. "And, in terms of older people, this study seems to indicate that our drive for sleep goes down as we age."