Here's Why You Sleep Much Less As You Age

In a study published in the journal Neuron this month, researchers found that insomnia occurs because certain brain mechanisms change as people age.

Lead study author Matthew Walker, head of the sleep and neuroimaging laboratory at University of California, Berkeley, said sleeplessness is the result of the loss of neuronal connections in the brain that pick up on the body’s cues that it’s tired. In experiments that compared the amount and type of chemical signals involved in sleep in younger mice to older ones, neuroscientists found that the chemical signature was the same regardless of age. The problem is that the receptors in the brain that receive that signal decline with age, Walker explained in a press release. That means the aging brain has the same sleep cues inside of it, but it’s unable to pick up on those cues. “It’s almost like a radio antenna that’s weak,” Walker added. “The signal is there, but the antenna just can’t pick it up.”

Walker said that while the assumption has been that insomnia was a consequence of aging, insufficient sleep may actually be a contributing factor to aging itself. Scientists have found causal links between a lack of sleep and cardiovascular disease, diabetes, and obesity. When it comes to memory, sleep is a “Goldilocks issue”: Both too much and too little aren’t very good, according to a Harvard-based Nurses’ Health Study.

The Sleep Foundation says that older people need seven to nine hours of sleep a night, the same amount as growing adolescents. But they are not getting it. The National Institute on Aging found that 13 percent of men and 36 percent of women over age 65 take more than 30 minutes to fall asleep. And they often sleep less deeply and wake up more often throughout the night.

But sleep deprivation can actually begin much earlier in life ― often affecting people in their late 20s and early 30s, Walker said. In fact, by the time a person hits 50, they will only have about 50 percent of the deep sleep that they were getting in their early 20s. By 70, individuals have little, if any, high-quality deep sleep. Sleeping pills, he said, are often prescribed to older adults. But a sedated sleep just means you aren’t waking up throughout the night, not that you are getting your necessary deep sleep.

Walker, who holds several patents focused on consumer-based sleep measures, is the author of the forthcoming book Why We Sleep. The National Institutes of Health funded this study.