Getting a good night’s sleep is a pretty crucial part of maintaining a healthy body and mind – that much we know. But for many of us, achieving a solid eight hours every night is easier said than done. Maybe you’ve been sipping on too much coffee; maybe your mattress is a little bit crap, or maybe you’re one of those unlucky sods who will be jolted awake by the sound of a gentle breeze outside your window.
There are many elements that can negatively impact your sleep quality, and as many of you will know first-hand, a terrible sleep can royally stuff up your day. What a lot of people don’t realise, however, is that at a certain point – you may as well have not gone to bed at all.
According to recent research, six hours of sleep is where that point begins.
That’s what researchers at the University of Pennsylvania School of Medicine found in their sleep study. They took 48 adults (ages 21-38) and restricted their sleep to four, six, or eight hours each night for two weeks. One unfortunate group was forced to stay awake for three whole days.
For each group, the researchers tested participants’ cognitive performance and reaction time every two hours when they were awake.
Unsurprisingly, those who got the full eight hours of sleep performed the best, while those who got only four hours a night did worse each day. The biggest surprise was for the six-hour sleep group. As Fast Company reports:
The group who got six hours of sleep seemed to be holding their own, until around day 10 of the study.
In the last few days of the experiment, the subjects who were restricted to a maximum of six hours of sleep per night showed cognitive performance that was as bad as the people who weren’t allowed to sleep at all. Getting only six hours of shut-eye was as bad as not sleeping for two days straight. The group who got only four hours of sleep each night performed just as poorly, but they hit their low sooner.
The study has a small sample size and some people seem to function on little sleep. However, one of the findings of the 2004 study was that those in the six-hour group didn’t even think they were that sleepy, even though they were doing more poorly on the tests.
So maybe reconsider if you’re really getting enough sleep.
The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. [Sleep via Fast Company]
This article has been updated since its original publication.