Wearing a fitness tracker such as a Fitbit or an Apple Watch can tell you all sorts of things about your health. I used my Fitbit only to count steps, however, until I felt groggy for a couple of days and checked the sleep stats.
They showed only 4 minutes of deep sleep, the most restful kind, on the night preceding the episode of grogginess. Deep sleep increased the next night to 16 minutes, still only a fraction of the ideal 1 to 1¾ hours.
I kept paying attention to the sleep stats for a couple of weeks and saw 5, 6, and 8 minutes of deep sleep on other nights. On only three nights did I get more than an hour.
My REM (rapid eye movement) sleep was also deficient, coming close to the desired 2 hours on only five nights and dipping below 30 minutes twice.
On the other end of the spectrum, I consistently got 5 to 6½ hours of light sleep when it should be only about half of the total.
I used to think that on the sleep/diet/exercise formula for health, I had the sleep part down with 7 to 8 hours a night. After finding out that my sleep phases don’t match the ideal, I wondered whether I was really getting a good night’s sleep.
During the night the body cycles several times through light, deep, and REM sleep, the stages serving different purposes. Deep sleep restores the body, builds muscles, and strengthens the immune system. REM sleep, when you typically dream, is essential for learning, memory, and cognition. Light sleep is important — it supports creativity, memory, and motor skills — but shouldn’t be three-quarters of one’s sleep total, as mine is.
It didn’t surprise me to learn that I’m typical among my contemporaries. Poorer sleep is another sign of growing old.
“As people get older, their sleep changes due to effects of an aging internal clock,” says the Sleep Foundation. “Older adults spend more time in the earlier, lighter stages of sleep and less time in the later, deeper stages. These shifts may contribute to older people waking up more often during the night and having more fragmented, less restful sleep.”
If feeling less rested weren’t enough, there’s another concern for those of us who had a parent with dementia. Research has linked declining deep sleep to a buildup of the beta-amyloid plaques that cause Alzheimer’s disease.
“Another thing to worry about,” said a friend, whose deep sleep stats are poor and whose mother had Alzheimer’s.
When an aging internal clock is responsible for lighter sleeping, can nothing be done?
I already practice much of the “good sleep hygiene” advice, such as retiring at a regular hour and avoiding screen time and food before bed. I could stop drinking liquids in the evening, although having to use the bathroom is not the only reason older people awaken. We wake up more than younger folks because we spend less time in deep sleep.
Maybe I’ll bring up sleep with my doctor the next time I see her, but in the meantime my solution is to stop checking the Fitbit’s sleep stats. An article in Consumer Reports about sleep trackers noted that the best evidence of whether you’re getting enough rest is how you wake up feeling.
“If the morning read of your Fitbit’s sleep stats leads you to start ‘doomscrolling’ about the health issues that can be caused by a lack of sleep,” the magazine said, “your watch probably isn’t doing you any favors.”
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How accurate are a Fitbit’s or smartwatch’s sleep stats anyway?
They should be taken with a grain of salt, Consumer Reports said. “A wrist-worn sleep tracker like the Fitbit can’t measure your brain’s electrical activity directly in the same way a laboratory sleep study does, where a patient wears an array of electrodes. Your Fitbit, like most wearable sleep trackers, is using other metrics, like physical movement, pulse rate, and breathing, to infer which stage you’re in, so it may be less accurate.”
Yep, we all have sleep issues at this age.
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