The British musician Max Richter recently released his latest composition. “Sleep” is a lullaby for the digital age which lasts more than eight hours. Barring notable exceptions, like Spain, developed nations have long given credence to the view that eight hours of uninterrupted sleep is key to a balanced mood and high performance at work.
Ironically, this is a standard which most people in these countries fail to reach. A global poll by the US National Sleep Foundation found that Britons only sleep for an average of six hours and 49 minutes on work nights. With sleep deprivation linked to lower productivity and a host of health problems, such as Alzheimer’s and high blood pressure, how much sleep is enough, and what is a sensible strategy?
THE “EIGHT HOURS” MYTH
There is much conflicting evidence around this issue, but a number of studies have challenged the “eight hours” dogma. Earlier this year, research by the University of Cambridge found that, out of 10,000 participants, those who got an average of eight hours shut-eye had a 46 per cent higher than average risk of suffering a stroke. While the research team recognised that a lack of sleep is regularly associated with a disrupted metabolism and higher cortisol levels, which is linked to stress and higher blood pressure, they said that further research was required to establish a link between more sleep and increased stroke risk.
So what is an appropriate amount? Gregg Jacobs of the University of Massachusetts told the BBC that seven hours is actually the median sleep duration for adults in the developed world. Sleeping less has also been linked to living longer. The University of Warwick’s Franco Cappuccio gathered data on the sleeping patterns of over 1m people, and found that those who got more than eight hours a night were 30 per cent more likely to have died than those who only slept for six to eight hours.
In the greater context of sleeping patterns in history, taking eight unbroken hours is a relatively recent development. According to sleep historian Roger Ekirch, before the work pressures of the Industrial Revolution, humans would sleep in two four-hour stints, waking in the middle of the night for around an hour to pray, write, talk with their spouses, and even visit neighbours.
With the advent of electricity and the pressures of modern life, people go to bed much later than before. Regardless, the benefits of segmented sleep remain. In the 90s, sleep scientist Thomas Wehr concluded that it is natural for humans to sleep “biphasically” when exposed to 14 hours of darkness a night, taking two hours to fall asleep, with a one hour break between sleep periods. Wehr surmised that taking just 15 minutes to fall asleep, as many of us do today, is a sign of the chronic sleep deprivation afflicting our generation. Wehr’s views are echoed by peers today; “maybe the brain can’t keep you asleep for prolonged periods,” speculates Mary Carskadon, a sleep researcher at Brown University.
Far from a sign of laziness or disinterest, falling asleep at your desk is considered a mark of diligence in Japan, where “inemuri” – or sleeping while present – is often seen in offices. But while power napping has been catapulted into the British public’s consciousness in recent years, few feel comfortable enough to take a nap in an open plan office in the middle of the day. However, companies with particularly radical office cultures, such as Google and HubSpot, have started to embrace the idea.
The benefits are numerous. Earlier this year, scientists at the Saarland University in Germany reported that taking a power nap of 45 to 60 minutes can improve your memory five-fold. And a study published by the Endocrine Society revealed that napping for 30 minutes could normalise the hormonal impact of getting just two and a half hours’ sleep.
“Napping may offer a way to counter the damaging effects of sleep restriction by helping the immune and neuroendocrine systems to recover,” said the study’s author Brice Faraut. “The findings support the development of practical strategies for addressing chronically sleep-deprived populations, such as night and shift workers.”