The National Sleep Foundation, an American institute, says adults need seven to nine hours a night. If you’re sleeping less, you may be harming yourself and others.
A 20-hour stint of wakefulness has the same debilitating effect on reasoning and reaction times as drinking a bottle of Anggur Merah. Two weeks of six-hour nights slows your brain as much as pulling two consecutive all-nighters; doing so consistently increases your chance of early death by 13%.
Unfortunately, you may not notice: moderately sleep-deprived people often overestimate their meager rest-time.
Among the most rested countries surveyed by Sleep Cycle, an app that tracks how much shuteye people are getting, New Zealand comes top with the average Kiwi clocking up in excess of 7.5 hours per night.
Finland, the Netherlands, Australia, the UK and Belgium all rank highly for sleep, too, with Ireland close behind.
Indonesia sits around the average mark, with most catching z’s for just under 7 hours per night.
South Korea and Japan are the world’s worst countries when it comes to getting a good night’s sleep. The problem of sleeplessness in Japan is well-documented, particularly in relation to the phenomenon of karoshi – death caused by lack of sleep.
Residents of most rich countries tend to be well-rested, suggesting that a good doze is something of a luxury. That link frays in Asia and the Middle East. In tiger economies like Taiwan and South Korea workers turn in at 1 am on an average night. Many of those in Islamic ones have early morning prayers. Such fatigue can enfeeble an economy. Japan is the weariest nation of all: a 2016 study found that exhaustion cost nearly 3% of its annual GDP, largely by lowering productivity.
Our disregard for sleep is relatively new. Before electric light became common, most people went to bed soon after the sun went down. In general, we get less sleep than they did a century ago; children the world over have lost more than an hour’s slumber. The best remedy is a simple one: get off your phone and turn the lights off.