Researchers say that two nights of broken sleep is enough to make people feel years older. They also say that getting regular, restful sleep is a key part of not feeling your real age.
Swedish psychologists found that people who were only allowed four hours of sleep for two nights in a row felt more than four years older on average. Some said they felt decades older because they were so sleepy.
When people were allowed to stay in bed for nine hours, the opposite happened, though the effect was not as strong. After getting enough rest, study subjects said they felt three months younger than their real age.
“Sleep has a big effect on how old you feel, and it’s not just the way you sleep,” said the study’s first author, Dr. Leonie Balter, a psychoneuroimmunologist at the Karolinska Institute in Stockholm. “Even if you only sleep less for two nights, it changes the way you feel.”
Balter said that the idea of looking and feeling many years older may have health effects beyond just making people feel older. It may make people eat less healthily, exercise less, and be less willing to meet new people and try new things.
The researchers did two tests. In the first, 429 people between the ages of 18 and 70 were asked to rate their age and say how many nights in the past month they had slept badly. A standard scale used in psychology study was also used to rate how sleepy they were.
Scientists found that volunteers felt three months older for every day they didn’t get enough sleep. On the other hand, volunteers who hadn’t had any bad nights in the previous month felt almost six years younger than their real age. But it wasn’t clear if not getting enough sleep made people feel older or the other way around.
In the second study, 186 volunteers between the ages of 18 and 46 were asked to rate how old they felt after two nights of getting nine hours of sleep each night and two nights of getting only four hours of sleep each night. The subjects felt 4.44 years older on average after two nights of not getting enough sleep than when they did get enough sleep. It wasn’t a surprise that feeling older was linked to feeling sleepier.
“Taking care of your sleep is the most important thing you can do to feel young,” Balter said.
In Proceedings of the Royal Society B, the psychologists talk about how people react to not getting enough sleep based on whether they are a morning person who gets up early and goes to bed early or an evening person who gets up late and stays up late. Even after getting a lot of sleep, evening types often felt older than their actual age. However, morning types felt older than their actual age when their sleep was interrupted.
Balter says that the results could be useful if they are proven. “It’s important to understand how subjective age can change,” she said. “If we can make people feel younger, they might be able to enjoy the benefits that come with that, like being more open to new experiences and keeping up with friends and family.”
Dr. Serena Sabatini, a psychologist at the University of Surrey who wasn’t part of the study, said the results were “promising.” However, she said that future research should focus on seeing if they hold for older people.
She also said, “Another important thing to think about in future research is looking at these mechanisms over time.” “This study shows that not getting enough sleep can change how we feel the next day. But what are the long-term effects of not getting enough sleep for months and years?”
A senior lecturer in psychology at Loughborough University named Dr. Iuliana Hartescu, who was also not involved in the study, said that not getting enough or good quality sleep was linked to living choices that have long-term effects on health.
She said, “Sleep is one behavior that can be changed and has an immediate, noticeable effect on health.” It takes a while to notice the results of a bad diet and not getting enough exercise. A bad night’s sleep instantly affects how you live your life 24 hours a day.
A different study that looked at more than 4,000 Europeans over 10 years found that people who worked out two or three times a week were much less likely to have insomnia and were better able to get the recommended six to nine hours of sleep every night.
Researchers from around the world looked at questionnaires filled out by people who took part in the European Community Respiratory Health Survey. The questionnaires asked people about their exercise habits, how long and how well they slept, and how sleepy they felt during the day. For ten years, volunteers at 21 places in nine countries were watched.
The study found that people who worked out at least twice a week for at least an hour a week were 42% less likely to have trouble falling asleep than people who didn’t work out. They were also 55% more likely to be “normal sleepers” who got enough sleep every night.