A lack of sleep can turn you into a grumpy ‘social leper’ who shuns human contact, a study suggests.
Sleep-deprivation activates brain areas that make you find other people threatening, a study found.
It also dampens down brain regions that promote being sociable.
Sleep-deprived people not only feel worse, but induce feelings of loneliness in other people looking at them.
But just getting one good night’s sleep made people in the experiment feel outgoing and confident again.
A study by the University of California, Berkeley, enrolled 18 healthy adults to a sleep laboratory and prevented them getting any sleep on one night.
Psychological tests showed that the sleep deprived wanted to avoid close human contact.
When asked how they felt afterwards, participants rated themselves ‘as feeling significantly more lonely’. Not only did the volunteers feel more unsociable, they made other people looking at them feel more lonely and ‘socially unattractive’.
Study author Matthew Walker said: ‘We humans are a social species. Yet sleep deprivation can turn us into social lepers.’
He added: ‘The less sleep you get, the less you want to socially interact. In turn, other people perceive you as more socially repulsive, further increasing the grave social-isolation impact of sleep loss. That vicious cycle may be a significant contributing factor to the public health crisis that is loneliness.’
Humans are often found to want to help, or ‘nurture’, other vulnerable members of their group. But the authors say this response does not kick in when we are tired. To test how sociable the sleep-deprived volunteers felt, they viewed video clips of individuals with neutral expressions walking towards them. When the person on the video got too close, they pushed a button to stop the playback– recording how close they allowed the person to get.
Sleep-deprived participants kept the approaching person at a significantly greater distance away – between 18 and 60 per cent further back – than when they had been well rested.
Volunteers also had their brains scanned as they watched the videos. In exhausted brains, researchers found heightened activity in a circuit called the ‘near-space network’. This is activated when the brain perceives human threats. In contrast, another circuit that encourages social interaction was shut down by sleep deprivation, worsening the problem.
The researchers also looked at whether just one night of good or bad sleep could influence one’s sense of loneliness the next day. They found that the amount of sleep a person got on any given night accurately predicted how lonely and unsociable they would feel. But Dr Walker stressed: ‘On a positive note, just one night of good sleep makes you feel more outgoing…’