Often, scorching heat ravaged me by day and frost by night; and sleep fled from my eyes. Genesis 31:40 (The Israel Bible™)
You might think that not sleeping well is your own business, or at least that of your spouse, but an Israeli researcher at the University of California at Berkeley and her colleagues have found that poor sleep can literally kill your social life.
Dr. Eti Ben Simon, a postdoctoral fellow in at UC’s Center for Human Sleep Science, and her supervisor, psychology and neuroscience Prof. Matthew Walker, have just published their findings in the prestigious journal Nature Communications.
Three years ago, at the Center for Brain Functions at Tel Aviv Sourasky Medical Center, Ben Simon found that getting too little sleep at night harms the brain’s ability to regulate emotions and cope with anxiety,
“Human beings did not evolve to be alone. Sociality plays a fundamental part in the wellbeing of Homo sapiens. Conversely, social isolation and loneliness are known risk factors for premature death, more so than being obese,” she said. Although social isolation can result in sleep impairment, it has been unclear in human or non-human species whether the opposite is true – does sleep loss lead people to feel lonely, become less social and enforce greater social separation from others?
Perhaps it is no coincidence that the past few decades have seen a marked increase in loneliness and an equally dramatic decrease in sleep duration, said Ben Simon. “Without sufficient sleep, we become a social turn-off, and loneliness soon kicks in.”
The two researchers found that sleep-deprived people feel lonelier and less inclined to engage with others, avoiding close contact in much the same way as people with social anxiety. Even worse is that the poor sleepers’ alienating messages them more socially unattractive to others. Even well-rested people feel lonely after just a brief encounter with a sleep-deprived person, triggering a viral contagion of social isolation.
The findings are the first to show a two-way relationship between sleep loss and becoming socially isolated, shedding new light on a global loneliness epidemic. “We humans are a social species. Yet sleep deprivation can turn us into social lepers,” said Ben Simon.
The researchers found that brain scans of sleep-deprived people – as they watched video clips of strangers walking toward them – showed powerful social repulsion activity in neural networks that are typically activated when humans feel their personal space is being invaded. Inadequate sleep also suppressed activity in brain regions that normally encourage social engagement.
“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 added. “That vicious cycle may be a significant contributing factor to the public health crisis that is loneliness.”
National surveys suggest that nearly half of Americans report feeling lonely or left out. Furthermore, loneliness has been found to increase one’s risk of mortality by more than 45 percent – double the mortality risk associated with obesity.
From an evolutionary standpoint, the study challenges the assumption that humans are programmed to nurture socially vulnerable members of their tribe for the survival of the species. Walker, who wrote the bestselling book Why We Sleep, has a hypothesis on why that protective instinct may be lacking in the case of sleep deprivation. “There’s no biological or social safety net for sleep deprivation as there is for, say, starvation. That’s why our physical and mental health implodes so quickly even after the loss of just one or two hours of sleep,” Walker suggested.
To gauge the social effects of poor sleep, the team conducted a series of intricate experiments using such tools as functional MRI brain imaging, standardized loneliness measures, videotaped simulations and surveys via Amazon’s Mechanical Turk online marketplace.
First, researchers tested the social and neural responses of 18 healthy young adults following a normal night’s sleep and a sleepless night. The participants viewed video clips of individuals with neutral expressions walking toward them. When the person on the video got too close, they pushed a button to stop the video, which recorded how close they allowed the person to get.
As predicted, sleep-deprived participants kept the approaching person at a significantly greater distance away – between 18% and 60% further back – than when they had been well-rested. Their brains were scanned as they watched the videos of individuals approaching them. In sleep-deprived brains, researchers found heightened activity in a neural circuit known as the “near space network,” which is activated when the brain perceives potential incoming human threats.
By contrast, another circuit of the brain that encourages social interaction – called the “theory of mind” network – was shut down by sleep deprivation, worsening the problem.
For the online section of the study, more than 1,000 observers solicited via Amazon’s Mechanical Turk marketplace viewed videotapes of study participants discussing commonplace opinions and activities. The observers were unaware that the subjects had been deprived of sleep and rated each of them based on how lonely they appeared and whether they would want to interact socially with them. Again and again, they rated study participants in the sleep-deprived state as lonelier and less socially desirable.
To test whether sleep-loss-induced alienation is contagious, researchers asked observers to rate their own levels of loneliness after watching videos of study participants. They were amazed to find that otherwise- healthy observers felt alienated after viewing only a one-minute video of a lonely person.
Finally, researchers looked at whether just one night of good or bad sleep could influence one’s sense of loneliness the next day. Each person’s state of loneliness was tracked via a standardized survey that asked such questions as, “How often do you feel isolated from others?” and “Do you feel you don’t have anyone to talk to?”
Notably, researchers found that 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.
“This all bodes well if you sleep the necessary seven to nine hours a night, but not so well if you continue to shortchange your sleep,” Walker concluded. “On a positive note, just one night of good sleep makes you feel more outgoing and socially confident, and furthermore, will attract others to you.”