Not getting enough sleep? You might be able to blame your age.
A new study found that time spent sleeping declines with age, dropping to the lowest point at age 40. At around age 50, people might start sleeping more again.
Researchers say the trend may be influenced by a combination of biological and lifestyle factors. But sleep duration doesn’t necessarily equate to quality of sleep, which appears to decline as people grow older.
The study evaluated data from over 11,000 people ages 6 and older. Participants wore a device called an accelerometer on their wrists to track movement. The data, collected between 2011 and 2014, included sleep duration, bedtime, and sleep efficiency.
“Sleep efficiency is simply a way of asking, if you have a given amount of time set aside for sleep, how well do you use that for sleep?” William Vaughn McCall, MD, MS, executive vice dean at the Medical College of Georgia, Augusta University and co-author of the study, told Verywell.
Although the time spent sleeping takes on a U-shaped development as people age, sleep efficiency consistently gets worse over time. A 40-year-old may be sleeping less, but they're probably fitting in higher quality sleep than someone who is 60.
“People who are shortchanged on bedtime are burning the candle at both ends,” McCall said. “They may sleep so hard that they are asleep as soon as they get in the bed and sleep until the alarm goes off. And their sleep efficiency can be very, very high.”
People who are older may be spending more time in bed, perhaps due to fewer lifestyle responsibilities or family demands, he added. However, it doesn't mean they're asleep for longer.
“Older people sometimes complain that they can't sleep through the night anymore,’” McCall said. “Sometimes part of the reason why is, well, you're spending more time in bed, and you simply can't fill up all that time with sleep.”
Findings showed that 20-year-olds had the latest bedtimes. School-aged and working-aged people displayed the most extreme variations in weekly sleep patterns versus weekend sleep patterns.
The study did not evaluate time spent napping or the depth of sleep.
Some people function just fine on little sleep or poor sleep. But if it starts to impact their daily life, there may be room for concern.
According to McCall, activities like safely driving a car, maintaining performance at work, and keeping up with personal relationships can say a lot about whether someone is getting good quality sleep.
“Everybody's made a little bit differently,” he said. “There are some people that might not be able to cope very well with the amount of sleep they get at age 40, but I think a lot of people can. My message to folks is that yes, sleep at night is very important. But the real measure of its effectiveness is how you feel during the day.”
It might not matter very much if you're not getting a lot of sleep. What matters more is how well you sleep and how you feel during the day.