older woman sleeping
Sleep Health

Can People Get By with Less Sleep?

People who sleep much less than they’re supposed to may be efficient sleepers, but their patterns of neural connections suggest they may also be more tired than they realize, new research shows.

The study, from the University of Utah, was published in Brain and Behavior.

“This is tantalizing evidence for why some people feel like they don’t need to sleep as much,” says study co-author and radiologist Jeff Anderson. “Maybe some brains are able to do what sleep does in little tiny epochs during the day.”

The reasons for sleep are still a mystery. “It’s one of the most interesting questions in all science: Why do we sleep in the first place?” Anderson says. “It’s incredibly disadvantageous to spend a third of our life asleep. There must be an important reason to do it, but why is still an active field of research.”

Some of the leading hypotheses hold that sleep clears the brain of compounds accumulated throughout the day, and allows memories to move from short-term to long-term memory storage.

For most people, getting less than the recommended seven to nine hours of sleep a night results in fatigue, irritability and some impairment in judgment and reasoning. Long-term short sleep duration has been linked to a host of mental and physical health consequences, including diminished cognitive performance, mood disturbance, obesity, coronary disease and all-cause mortality risk.

But some people who get less than six hours of sleep a night report feeling no ill effects. In 2009, University of Utah neurologist Christopher Jones and colleagues found a rare genetic mutation that was associated with short-duration, efficient sleep. Many genetic factors are involved in sleep, and a combination of such factors may lead some people to feel that they need less sleep than others.

“Most people feel terrible when they get less than six hours of sleep,” says study co-author and psychology professor Paula Williams. “What’s different about these short sleepers who feel fine? Is there something different going on in terms of brain function? Although they report no daytime dysfunction from short sleep, what if their perceptions are inaccurate?”

To begin answering those questions, Williams, Anderson, Jones and psychology graduate student Brian Curtis, who is first author on the new study, looked into how people’s brains are wired together. “Most of the cells in the brain are just a little thin layer of gray matter cells along the surface,” Anderson says. “Everything else in the middle are connections between those points on the surface and a few way stations in between. So figuring out where those connections go, which points are connected and which points aren’t in the gray matter is really everything about how the brain works.”