We’ve all heard about the merits of a good night’s sleep in everything from improved cognitive function to anti-aging.
A poor night’s sleep, on the other hand, has been blamed for bad diets to anxiety levels.
New research from University of Michigan, however, found that cultural factors most influenced when people went to sleep and for how long they slept. The study used a free smartphone app aimed at reducing jetlag to gather the sleep data from more than 5400 people in 100 countries.
As it turns out, Australians have the earliest bedtime of any country at 10:45pm, Spaniards were the latest to bed, and people in Singapore and Japan were the most sleep-deprived, sleeping for 7 hours and 24 minutes per night, on average. The Dutch got the most sleep than any other nation, with a national average of 8 hours and 12 minutes. Meanwhile, those in the United Arab Emirates slept in the latest, emerging from their slumber just before 7:45am.
As for our home and native land, Canadians typically sleep 8 hours per night, rising between 7:00-7:15am and hitting the sheets between 11:00pm-11:15pm.
Most significantly, the study found that social and cultural pressures are more influential than natural circadian rhythms (internal clocks). This is especially the case in the evening, resulting in later bedtimes.
But just because people went to bed later didn’t mean that they necessarily slept longer.
“Across the board, it appears that society governs bedtime and one’s internal clock governs wake time, and a later bedtime is linked to a loss of sleep,” said Daniel Forger, professor of mathematics at the University of Michigan and co-author of the study published by the American Association for the Advancement of Science in the journal Science Advances.
“At the same time, we found a strong wake-time effect from users’ biological clocks – not just their alarm clocks. These findings help to quantify the tug-of-war between solar and social timekeeping.”
Of the more interesting findings, people who spend more time in sunlight also tend to head to bed earlier and sleep longer than those who get more indoor light.
The study also found differences between the sexes.
Globally, the research found that middle-aged men got the least sleep and women slept about 30 more minutes than men on average. The females did this by scheduling more sleep (and sticking to a schedule), going to bed earlier and waking up slightly later.
Also of interest is the app used to gather data for the study, a handy tool for frequent travellers. Called Entrain, the app helps travellers adjust to different time zones through a customized schedule of light and darkness. To use it, users must enter their normal wake time, bedtime, home time zone, and “typical” amount of light exposure. The users are then given an option to submit their data anonymously to the University of Michigan; hence, the study.
With information from thousands of people, the researchers then analyzed it for patterns. Any correlations that arose were put to the test through a circadian rhythm simulator. The simulator — a mathematical model that I’m not going to pretend to understand — is based on deep knowledge of how light affects the brain’s suprachiasmatic nucleus (in other words, the group of neurons behind the eyes that regulates our internal clocks). The model allowed the researchers to dial the sun up and down to determine whether the correlations still held in extreme conditions.
In addition to their findings, the researchers stress that sleep is more important than many of us realize. Even if you get six hours a night, you’re still building up a sleep debt (FYI, the recommended minimum is seven hours).
“It doesn’t take that many days of not getting enough sleep before you’re functionally drunk,” said co-author Olivia Walch. “Researchers have figured out that being overly tired can have that effect. And what’s terrifying at the same time is that people think they’re performing tasks way better than they are. Your performance drops off but your perception of your performance doesn’t.”
As a growing number of millennials take the entrepreneurial route, things like hard bedtimes are increasingly less important than getting the required amount of sleep. Unless they have early morning meetings, many of the most successful entrepreneurs I know stick to a defined amount of sleep, clocking in the same duration regardless of bedtime – whether that means 10:00pm or 3:00am.