Sleep Time Is Cultural—Nautilus

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In Japan, late nights are a lifestyle – the last trains of the night are often filled with people who return home at midnight of work or an evening. In fact, studies systematically find that people living in Japan get much less nod to night than people living in other parts of the world. And yet Japan also has the longest average lifespan in one of the most advanced economies in the world. There are many elderly people.

This has a paradox. Sleep research has always shown that people who sleep less hours suffer from lower health results and even live shorter lives. So how can the Japanese sleep so little and still seem to prosper in old age?

Christine or, assistant professor at the University of Victoria School of Nursing in Canada, with her husband Steven Heine, professor of cultural psychology at the University of British Columbia, decided to dive into this question of the way in which culturally distinct differences in sleep health have an impact on health with a study of 5,000 people from 20 different countries.

“Essentially, we asked: is there a universal sleep that is the healthiest for everyone, or does this ideal vary according to the country?” said or. “And do people feel healthier when their sleep corresponds to what is typical or expected of a culture?”

You cannot use eight hours as a magic number.

With a team of other researchers, they found that the range of sleeping times varied considerably from 6 hours and 18 minutes per night for Japan at 7 am and 52 minutes per night for France (the United States was near the spectrum of the duration of sleep, with around 7 hours per night).

But when they examined the relationship between the health of individuals and their sleep habits, controlling factors such as smoking and food nutrition, they found that the amount of sleep necessary for optimal health was lower for people from countries with shorter sleep times. They also found that people from countries with shorter sleep periods did not have shorter expectations of life, nor higher rate of heart disease or diabetes. These short sleep cultures in fact had lower obesity rates than people living in countries with longer sleep times.

“This suggests that we learn to sleep from our culture, which shapes the processes of our sleep,” explains Heine. Research was published in the journal PNA last month.

The team of researchers also found that people tended to be healthier if their sleep habits corresponded closely to the standards of their place of life than if they diverged. This is aligned with other research, they say, which show that when people integrate culturally with others in the places where they live – in what they eat or how they show emotions – their health is better overall.

It is not only a question of genetics. The behavior, and the physiological response to it can be learned, suggest the researchers. Having a sleep schedule aligned with that of others in your community could help reduce the stress related to planning, they suggest. “Our basic physiological needs are shaped by the way we interact with our cultures,” explains or.

A person’s needs can also move when they move to a new area with a separate culture, they say. A previous study by the group has shown that university students in Japan were sleeping an hour less than university students in Canada, but felt even less sleepy and had better health – while Canadian Eastern Asian students had more similar behaviors and attitudes to those of European Canadians. “This suggests that we are shaped by our local culture in terms of our sleep,” explains Heine.

Heine says that the results raise interesting questions for future research and have reached a wider phenomenon. “The way we sleep the needs is shaped by cultural learning,” he says. “There is no unique ideal sleep that is best for everyone. So you can’t use eight hours as a magic number.”

The team provides for a future study to examine the variations of the different sleep stages that people are going through overnight – like a deep sleep compared to lighter sleep. For example, Heine wonders if cultures that sleep less hours can take a deep sleep faster than others – so “the French probably spend more time in some of the lighter sleep stages than, let’s say, the Japanese”.

Anders Fjell, a psychologist at the University of Oslo in Norway, said that the study was new in the use of intercultural comparisons to show that sleep has an important cultural component. “The study shows that the most healthy people have different sleep durations linked to the way the company examines the importance of sleep,” he said.

He adds that the results suggest that the natural variation in the duration of sleep has no strong causal effect on health and varies rather depending on the individual and cultural factors. The duration of sleep “should not only be considered from a biomedical point of view”, he says.

Most people still sleep too little, said or – the results of the study also suggested that the average sleep duration for each of the countries was lower than what is optimal for the health of this country. So, although there is no unique sleep that is ideal for everyone in the world, most people could benefit from additional rest, let’s say or. No matter where you live or when you sleep, she says, “You probably don’t sleep enough.”

Lead image: Jenny on the moon / Shutterstock

• Katharine Gammon

  Published on June 18, 2025

  Katharine Gammon is an independent scientific writer based in Santa Monica, California, who writes on the environment, science and parenting. You can find it on X (formerly known as Twitter) @kategammon.