Not spending enough time in the Land of Nod could turn you into a literal sleepyhead, reducing your cognitive capacities to the point of being “functionally drunk,” according to the co-author of a new study into sleeping patterns around the world. Though the fact that sleep deprivation isn’t particularly good for your mental alertness probably won’t come as much of a surprise, the study does provide some interesting insights into the factors that cause us to cut down on our much-needed shut-eye.
To conduct the research, the study authors collected data from several thousand users of a mobile app designed to help people cope with jet lag. Users from over 100 countries supplied information about their sleeping schedules, age, sex, and nationality.
The researchers also created a mathematical model of the circadian clock – often referred to as the body clock – which governs our natural bedtime and waking time. Under normal conditions, this is mainly influenced by our level of exposure to sunlight, which is recorded by a cluster of neurons behind the eye called the suprachiasmatic nucleus, in order to synchronize our sleeping patterns with natural cycles of day and night.
However, in the modern world of on-demand TV shows and global communications, lights-out time is now controlled by society rather than the Sun, resulting in sleeping schedules that are totally out of whack with Earth’s rotation.
By comparing the data collected from app users with their statistical model for the circadian clock, the researchers were able to notice certain population-wide unnatural habits. In particular, they found that, while people from different countries tended not to differ too much in their waking times, considerably more variation could be seen in their bedtimes. In other words, “mean sleep duration by country was predicted by bedtime and not by wake time.”
Explaining this finding, the study authors write that “biological cues around bedtime are either weakened or ignored for societal reasons, thereby leading individuals to delay their bedtime and truncate their sleep duration as a result.”
Our sleep cycles are naturally controlled by our circadian clock. happystock/Shutterstock
Looking at how these societal pressures affect bedtime across the globe, the researchers discovered that people from the Netherlands spend the most amount of time recharging their batteries, with an average of 8 hours 12 minutes sleep per night. In contrast, those from Singapore and Japan have the shortest slumbers, which last for seven hours 24 minutes.
The data also reveals that women tend to sleep for slightly longer than men, and that variation in people’s sleeping habits tends to decrease with age. Writing in the journal Science Advances, the study authors explain that this may be due to age-related changes in our circadian clocks, whereby as we get older, we find that we are only able to sleep between certain hours.
Despite the fact there is less than an hour’s difference between the two extremes identified in the paper, the authors insist that missing out on just a small amount of all-important sleep time could have major implications for our general ability to do life. In a statement, study co-author Olivia Walch explained that “it doesn't take that many days of not getting enough sleep before you're functionally drunk,” adding that, when overly tired, “people think they're performing tasks way better than they are. Your performance drops off but your perception of your performance doesn't.”