Two nights of interrupted sleep can make people feel years older, research shows

Two nights of interrupted sleep are enough to make people feel years older, according to researchers, who said consistent, restful sleep was a key factor in avoiding feeling your true age.

Psychologists in Sweden found that volunteers felt on average more than four years older when they got just four hours of sleep for two consecutive nights, with some claiming the sleepiness made them feel decades older.

The opposite was observed when people were allowed to stay in bed for nine hours, although the effect was more modest: Study participants claimed to feel on average three months younger than their actual age after adequate rest.

“Sleep has a big impact on how old you feel and it’s not just your long-term sleep patterns,” says Dr. Leonie Balter, a psychoneuroimmunologist at the Karolinska Institute in Stockholm and first author of the study. “Even if you sleep just two nights less, it has a real impact on how you feel.”

Besides simply feeling more worn out, the perception that they are many years older can affect people’s health, Balter said, by encouraging unhealthy eating, reducing exercise and making people less willing to socialize and experience new things. to do.

The researchers conducted two studies. In the first part, 429 people between the ages of 18 and 70 answered questions about how old they felt and how many nights they had slept poorly in the past month. Their sleepiness was also assessed according to a standard scale used in psychological research.

For every day of bad sleep, the volunteers felt on average three months older, the scientists found, while those who reported no bad nights in the previous month felt on average almost six years younger than their actual age. However, it was unclear whether poor sleep made people feel older or vice versa.

In the second study, researchers surveyed 186 volunteers aged 18 to 46 about how old they felt after two nights of copious sleep, in which they stayed in bed for nine hours each night, and two nights in which they slept only four hours each night. . After two nights of limited sleep, participants felt on average 4.44 years older than when they had sufficient sleep. It’s not surprising that feeling older is linked to feeling sleepier.

“If you want to feel young, the most important thing is to protect your sleep,” says Balter.

To write Proceedings of the Royal Society Bpsychologists describe differences in people’s responses to sleep loss depending on whether they are a morning person, who gets up early and goes to bed, or a night person who gets up late and retires late. Evening types tended to feel older than their actual age even after adequate sleep, but morning types were hit harder by how old they felt when their sleep was disrupted.

Balter says the findings, if confirmed, could be put to good use. “It’s important to realize how malleable subjective age is,” she said. “If we can make people feel younger, they may experience associated benefits, such as a greater willingness to seek new experiences and be socially and physically active.”

Dr. Serena Sabatini, a psychologist at the University of Surrey who was not involved in the study, called the results “promising” but said investigating whether they hold up in older people should be a priority for future research.

“Another important thing to consider in future research is an exploration of these mechanisms over time,” she added. “This study tells us that a poor night’s sleep can affect how we feel the next day, but what are the cumulative effects of a poor night’s sleep over months and years?”

Dr. Iuliana Hartescu, senior lecturer in psychology at Loughborough University, who was also not involved in the study, said insufficient or poor sleep quality is important for lifestyle behaviors that ultimately affect long-term health.

“Sleep is an adaptable behavior that has an immediate noticeable effect on health,” she said. “It takes some time before the effects of poor diet and low physical activity are noticeable. The effect of a poor night’s sleep is immediate and affects all other 24-hour lifestyle behaviors.”

A separate ten-year study of more than 4,000 Europeans found that those who consistently exercised two to three times a week were significantly less likely to experience insomnia than inactive people, and were better able to get the recommended six to nine hours of exercise. to fetch. sleep every night.

The international team of researchers analyzed questionnaires from people taking part in the European Community Respiratory Health Study about their exercise habits, how well and for how long they slept, and how sleepy they felt during the day. Volunteers at 21 locations in nine countries were followed for ten years.

Those who exercised two or more times a week, for at least an hour a week, were 42% less likely to have trouble falling asleep than inactive people, the study found, and 55% more likely to be “normal sleepers.” who developed a sleep disorder. healthy amount of shut-eye every night.

“This study has a long follow-up period, ten years, and strongly indicates that consistency in physical activity may be an important factor in optimizing sleep duration and reducing insomnia symptoms,” the authors said. write in BMJ Open.