She sleeps four hours a night with the help of a pill. She’s 95

Our sleep changes as we age. We sleep more lightly and more fragmented, but we keep sleeping

Last week I spoke to a woman who wore her heart on her sleeve. A true Amsterdam native. She had lived in the capital her entire life, had lived through the war, and — according to her — slept only four hours a night. And only with the help of a pill.

“That’s because I’m old,” she said, with the certainty of someone who had long ago decided that discussion was pointless. “When you get older, you just don’t sleep anymore.”

I nodded. But it wasn’t entirely true.

Aging changes your sleep

Sleep changes throughout your entire life. While a baby can sink into deep rest for hours, sleep becomes lighter and more fragmented as the years pass. Your biological need for sleep, however, generally remains seven to eight hours even at an older age. What changes is the depth of sleep. A twenty-year-old may get a hundred minutes of deep sleep per night; for someone in their seventies, that has declined to thirty or forty minutes. The brain’s “master clock” — the suprachiasmatic nucleus — can shrink with age, and synchronization with daylight becomes less efficient. Melatonin and other hormones no longer do their work as smoothly.

That woman with four hours of sleep on a pill, her perfectly straight posture and unmistakable Amsterdam humor, may actually be one of the most reassuring pieces of evidence imaginable. Not because chronically too little sleep is harmless, but because the human body is still capable of adapting and surviving, even after 95 years.

The media scare insomniacs

Still, chronic insomniacs often get a rough deal in the media (and I’m sometimes guilty of it in my own blogs as well). They tell you that six hours of sleep damages your brain, destroys your immune system, and causes your heart to fail. That your risk of depression increases. It’s not complete nonsense, but something about the certainty with which these findings are presented bothers me. What’s missing is nuance: almost all of that research was done on people who normally slept well and then had their sleep disrupted. And there is rarely a reminder that correlation is not the same as causation.

A common model used to study the effects of insomnia is simple: deprive good sleepers of sleep. Healthy adults are restricted to four or six hours of sleep for several consecutive nights, after which their cognitive functioning is measured. But in that case, you are not measuring the effects of chronic insomnia. You are measuring sleep deprivation. And that is fundamentally different.

The origin of sleep deprivation matters

One study compared people who were voluntarily restricted in their sleep with people suffering from chronic insomnia. The voluntarily sleep-deprived group made significantly riskier decisions than the group with chronic insomnia.

So the origin of sleep deprivation appears to matter.

I recognize that from my own experience as well. The first time I went a night without sleep and got into a car, I felt like a danger on the road. My eyes burned, my reaction time felt turtle-slow, and I was swerving. By the twentieth sleepless night, I was simply driving in a straight line to work. Not because I felt good, but because my body and mind had adapted.

Scientifically speaking, the brain does indeed seem to shift down a gear under prolonged sleep restriction but it adapts.

Not an argument for poor sleep

I am not making a case for poor sleep. Sleep is the most underrated recovery tool we have, and there is a great deal you can improve by handling it consciously — even at an older age. Small adjustments in daily rhythm, daylight exposure, nutrition, coffee, alcohol, exercise, and timely relaxation can do more than you might expect.

But for those who have struggled for years, for those for whom the pill is no longer really a choice — for the Amsterdam woman with her perfectly straight back — sleep is not the only thing by which a life is measured.

She lived through a war. She gave birth to children and cared for grandchildren. She got up every morning. And she never lost her sense of humor

That counts too.