So what is it about sleep that helps us live longer? Here’s what the research says.

What’s the Link Between Sleep and Aging?

A growing body of evidence suggests that poor sleep may accelerate biological aging, meaning aging on the cellular level.

This damage shortens the length of telomeres, the protective "caps" on the ends of chromosomes that prevent DNA from breaking down when cells divide. "The telomeres get shorter until the cell either dies or gets stuck in what’s known as cellular senescence," says Aric Prather, PhD, a coauthor of the review and the director of the University of California San Francisco Center for Health and Community. "These senescent cells tend to be inflammatory and contribute to the development of age-related diseases," he says. (Common age-related diseases caused by inflammation include heart disease, type 2 diabetes, and dementia.)

"In essence, some studies suggest that those who are getting less sleep than they probably need may be aging at a faster rate than those who are sleeping better," Dr. Prather explains.

How Sleep Protects the Brain Across the Lifespan

Researchers are still unraveling the link between sleep and brain health. But recent studies point to a potential clue.

"When sleep is disrupted, this cleaning process becomes less effective," says Santiago Clocchiatti-Tuozzo, MD, a neurology resident at Yale New Haven Hospital who researches the relationship between sleep and brain health. Even a single night of sleep deprivation can increase amyloid accumulation in the brain, he says, and chronic sleep loss appears to accelerate the buildup of these proteins over time. "Sleep is not simply ‘rest'; it is an essential maintenance period for the brain."

How Sleep Supports Other Body Systems

When it comes to longevity, sleep's benefits go beyond the brain. Studies suggest that sleep has whole-body effects that may extend the lifespan.

Keep in mind, however, that most of the research in this area is observational, says Jamie Zeitzer, PhD, a codirector of the Center for Sleep and Circadian Sciences at Stanford University in Palo Alto, California. So researchers don't yet know for sure if sleep itself is the balm or if it's that sleep enables other behaviors that support longevity.

With that in mind, here's what research has uncovered about how sleep might support the rest of the body.

• Heart During sleep, your heart rate slows and your blood pressure decreases, which is crucial for long-term heart health, Prather says. When you don't get enough sleep, your blood pressure stays higher for longer, putting strain on your cardiovascular system and increasing your risk for heart disease and stroke.
  Sleeping fewer than about six hours per night has also been linked to more plaque buildup in the arteries and a higher risk of heart attack.

• Gut The relationship between sleep and gut health goes both ways: a lack of quality sleep may reduce beneficial bacteria in the gut, and poor gut health may, in turn, impact sleep quality.
   That may be bad news for longevity, given that research links good gut health to healthy aging.

• Immune System Sleep loss weakens key immune functions, Dr. Clocchiatti-Tuozzo says, such as natural killer cell activity and the production of antibodies, both of which help you fight off infections. It also stokes inflammation, which can increase your risk for heart and metabolic disorders.

• Metabolism Consistent, quality sleep is linked to a lower risk of metabolic conditions, including obesity and type 2 diabetes.
   "Insufficient sleep alters hormones that are important for regulating metabolism and energy balance," explains Peter Liu, MD, PhD, a professor of medicine at the David Geffen School of Medicine at UCLA and a senior investigator at the Lundquist Institute at Harbor-UCLA Medical Center in Torrance, California. These shifts can lead to insulin resistance (when cells fail to respond effectively to insulin, leading to high blood sugar), he says, and eventually type 2 diabetes.
  By age 50, the life expectancy of people with type 2 diabetes is six years shorter than it is for people without the condition.

Why Sleep Quality Matters

So how do you know if you're getting enough of the quality sleep that's linked to longevity? "People who wake up feeling rested and can stay alert during the day are generally getting sufficient restorative sleep," Clocchiatti-Tuozzo says.

In contrast, the following are signs you may not be getting enough quality sleep, per Clocchiatti-Tuozzo:

• Difficulty falling asleep
• Frequent nighttime awakenings
• Persistent fatigue or excessive daytime sleepiness

You might also notice a decline in your ability to handle mental tasks like thinking, learning, making decisions, and paying attention, Liu says.