People help each other – that is one of the foundations of civilized society. But a new study by researchers at the University of California, Berkeley, reveals that lack of sleep dulls this basic human quality, with real consequences.
Lack of sleep is known to be associated with an increased risk of cardiovascular disease, depression, diabetes, hypertension and overall mortality. However, these new discoveries show that lack of sleep also weakens our basic social conscience, causing us to withdraw our desire and willingness to help other people.
In part of the new study, the researchers showed that charitable giving in the week after the start of daylight saving time, when residents in most states “jump forward” and lose an hour of daylight, dropped by 10% — a decline not seen in states that do not change the clocks or when states return to standard time in the fall.
The study, led by UC Berkeley researcher Eti Ben Simon and Matthew Walker, a UC Berkeley professor of psychology, adds to a growing body of evidence showing that insufficient sleep not only harms the mental and physical well-being of an individual, but also compromises bonds between individuals – and even the altruistic feeling of an entire nation.
“Over the past 20 years, we’ve discovered a very intimate link between our sleep health and our mental health. In fact, we haven’t been able to discover a single serious psychiatric condition where sleep is normal,” Walker said. “But this new the work shows that lack of sleep not only harms the health of an individual, but impairs social interactions between individuals and furthermore impairs the very structure of human society itself. How we function as a social species – and we are a social species – seems deeply dependent on how much sleep we get.”
“We’re starting to see more and more studies, including this one, where the effects of sleep loss don’t just stop with the individual, but spread to those around us,” Ben Simon said. “If you don’t get enough sleep, it doesn’t just harm your own well-being, it harms the well-being of your entire social circle, including strangers.”
Ben Simon, Walker and colleagues Raphael Vallat and Aubrey Rossi will publish their results on August 23 in the open access journal PLOS Biology. Walker is director of the Center for Human Sleep Science. He and Ben Simon are members of the Helen Wills Neuroscience Institute at UC Berkeley.
Insomnia dampens the theory of mind networks
The new report describes three separate studies that assessed the impact of sleep loss on people’s willingness to help others. In the first study, the researchers placed 24 healthy volunteers in a functional magnetic resonance imaging (fMRI) camera to scan their brains after eight hours of sleep and after a night without sleep. They found that areas of the brain that form the theory of mind networks, which are engaged when people empathize with others or try to understand others’ wants and needs, were less active after a sleepless night.
“When we think about other people, this engages the network and allows us to understand what other people’s needs are: What are they thinking about? Do they hurt? Do they need help?” said Ben Simon. “But this network was markedly weakened when individuals were sleep deprived. It’s as if these parts of the brain don’t respond when we try to interact with other people after not getting enough sleep.”
In a second study, they tracked more than 100 people online over three or four nights. During this time, the researchers measured the quality of their sleep – how long they slept, how many times they woke up – and then assessed their desire to help others, such as holding an elevator door open for someone else, volunteering or helping someone injured . stranger on the street.
“Here we found that a decrease in the quality of someone’s sleep from one night to the next predicted a significant decrease in the desire to help other people from one subsequent day to the next,” Ben Simon said. “Those with poor sleep the night before were the ones who reported being less willing and eager to help others the next day.”
The third part of the study involved mining a database of 3 million charitable donations in the United States between 2001 and 2016. Did the number of donations change after the change to daylight saving time and the potential loss of an hour of sleep? They found a 10% drop in donations. The same dent in compassionate gift-giving was not seen in regions of the country that did not change the clocks.
“Even a very modest ‘dose’ of sleep deprivation — here, just the loss of a single hour of sleep opportunity associated with daylight saving time — has a very measurable and very real impact on people’s generosity and thus how we function as a connected society,” Walker said. “When people lose an hour of sleep, it is a clear hit on our innate human goodness and our motivation to help other people in need.”
A previous study by Walker and Ben Simon showed that sleep deprivation forced people to withdraw socially and become more socially isolated. Lack of sleep also increased feelings of loneliness. Even worse, when the sleep-deprived individuals interacted with other people, they spread their loneliness to the other individuals, almost like a virus, Walker said.
“When we look at the big picture, we begin to see that lack of sleep results in a rather antisocial and, from a helpful perspective, antisocial individual, which has many consequences for how we live together as a social species,” he said. “Lack of sleep makes people less empathetic, less generous, more socially withdrawn, and it’s contagious—it’s the contagion of loneliness.”
“The recognition that the quantity and quality of sleep affects an entire society, caused by a decline in prosocial behavior, can provide insight into our societal state today,” Walker added.
This finding also offers a new approach to improving these specific aspects of our society.
“Promoting sleep, rather than shaming people for getting enough sleep, can very tangibly help shape the social bonds we all experience every day,” said Ben Simon.
“Sleep, it turns out, is an incredible lubricant for prosocial, connected, empathetic, kind and generous human behavior. In these divisive times, if ever a strong, prosocial lubricant was needed to enable the very best version of us even in society, it now appears to be,” said Walker, author of the international bestseller, Why we sleep. “Sleep can be a wonderful ingredient that makes it possible to help between people.”
“Sleep is essential to all aspects of our physical, mental and emotional lives,” said Ben Simon. “When sleep is undervalued in society, not only do we get sleep-deprived doctors, nurses and students, but we also suffer from unfriendly and less empathetic interactions on a daily basis.”
In developed countries, more than half of all people report getting insufficient sleep during the work week.
“It’s time as a society to abandon the idea that sleep is unnecessary or wasted and, without feeling embarrassed, start getting the sleep we need,” she added. “It is the best form of kindness we can offer ourselves, as well as the people around us.”