Sleep Through the Decades

How sleep changes with age, once you're an adult.

From the WebMD Archives

Babies can sleep through a circus. Older kids may fight bedtime. And teens -- good luck getting them out of bed on a weekend.

But what about you -- the grown-up? Your sleep life is still changing -- and not just because time is passing.

How does sleep work in adulthood? Does it change -- for better or worse -- as we age? And why do we feel like we never get enough of it?

An average adult needs between 7.5 and 8 hours of sleep per night. “But many people can function with 6 hours' sleep, and there also some who need 9 hours or more,” says Sudhansu Chokroverty, MD, professor and co-chair of neurology and program director for clinical neurophysiology and sleep medicine at the New Jersey Neuroscience Institute at JFK Medical Center in Edison, N.J.

“The amount of sleep needed to function the next day varies from individual to individual, and is determined genetically and hereditarily," says Chokoroverty, who is also a neuroscience professor at Seton Hall University's School of Health and Medical Sciences.

Grown-Up Sleep

The biggest, most dramatic change in our deep sleep and satisfaction with sleep takes place as we move from adolescence into young adulthood.

“Most adolescents feel like they sleep terrifically, and if you try to wake them up, you’re not even sure they’re alive,” says Robert Simpson, MD, assistant professor in the University of Utah's division of pulmonary medicine and a sleep medicine specialist. “That’s because they have lots of what we call deep, slow-wave sleep.”

Sleep is broadly split into two big categories: REM (rapid eye movement) sleep, when we’re dreaming, and non-REM sleep. Non-REM sleep moves through several, progressively deeper stages:

  • Stage I: a light doze, not very restorative
  • Stage II: middle sleep, restorative
  • Stage III: slow-wave deep sleep, the most restorative of all

“There’s a fairly precipitous decline in deep slow-wave sleep through the teen years into the early 20s,” Simpson says. “That tends to be replaced with middle sleep, stage II.”