Having a bad night's sleep doesn't do anything good for anybody, and it may be even worse than we think. We've all seen and felt how having had too little sleep can disconnect us from our daily lives and turn us into zombies. But it can also affect us socially — and not in a good way.

“We humans are a social species. Yet sleep deprivation can turn us into social lepers,” says Matthew Walker, co-author of a study looking at the social effects of lack of sleep, in a statement. Being tired makes us shy away from human contact and alienates us from others. In the end, it leaves us lonely.

A Vicious Cycle

A lack of sleep makes us less interested in social interaction, and what it does to our general attitude and even physical appearance can also drive others away. “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,” Walker, a professor of psychology and neuroscience at the University of California, Berkeley, said. “That vicious cycle may be a significant contributing factor to the public health crisis that is loneliness,” he added. And that's bad for our health.

Two Less-than-Social Networks
Eighteen young adults came to the laboratory both after a sleepless night and after a night of normal sleep. They were shown videos of people with neutral expressions on their face approaching them and would push a button to stop the video when they felt the people were getting too close. After a sleepless night, they kept the people 18 to 60 percent further away, indicating a greater desire for isolation.

Brain scans (fMRI) of the 18 showed there were two different forces acting to keep people more socially isolated when they were short on sleep. First, there was stronger activity in a neural circuit known as the Near Space network, which kicks in when the brain sees people approaching when they were sleep-deprived. And second, there was a strong decrease in activity in another brain network after sleep deprivation that encourages social interaction. So their interest in socializing dropped, making the problem worse.

Sleep-deprived people were consistently rated as lonelier and less socially desirable.

The amount of sleep a person got from one night to the next accurately predicted how lonely and unsociable they would feel from one day to the next.

Videos interviews of those same 18 people were shown to over 1,000 online observers in a second part of the study. The observers rated the 18 subjects on how lonely they appeared and how socially desirable they seemed. Sleep-deprived people were consistently rated as lonelier and less socially desirable.

Loneliness is Contagious

The alienation of the sleep-deprived also appears to be contagious, at least in the short-term. When observers rated their own loneliness after they had watched the videos of sleep-deprived people who were not interested in social interaction, they rated themselves as significantly lonelier after watching a video of someone who was sleep-deprived. In fact, the lonelier they rated an individual in a video, the lonelier they felt after viewing that video.

The amount of sleep a person got from one night to the next accurately predicted how lonely and unsociable they would feel from one day to the next.

The good news is that when researchers looked at people over two nights and the following two days, with the people sleeping as they chose for those two nights, they found that feelings of loneliness and isolation rose after a person got poorer sleep and fell when they got better sleep. So if you are worried about your social life, make the effort to get more rest. As Walker says, “…[J]ust one night of good sleep makes you feel more outgoing and socially confident, and…will attract others to you.”

The study is published in Nature Communications, which is open access.