It has long been known that lack of sleep affects your physical health and increases your risk of cardiovascular disease, depression, diabetes and high blood pressure. But new research from the University of California at Berkeley shows a lack of sleep can inhibit your social conscience and make you less willing to help others and be more stingy with your money.
UC Berkeley research scientists Eti Ben Simon and Matthew Walker found insufficient sleep impacts a person’s physical and mental health and can hinder the normal bonds between individuals. They published their findings in the journal PLOS Biology.
"Over the past 20 years, we have discovered a very intimate link between our sleep health and our mental health. Indeed, we've not been able to discover a single major psychiatric condition in which sleep is normal," Walker said. "But this new work demonstrates that a lack of sleep not only damages the health of an individual, but degrades social interactions between individuals and, furthermore, degrades the very fabric of human society itself. How we operate as a social species—and we are a social species—seems profoundly dependent on how much sleep we are getting."
"We're starting to see more and more studies, including this one, where the effects of sleep loss don't just stop at the individual, but propagate to those around us," said Ben Simon. "If you're not getting enough sleep, it doesn't just hurt your own well-being, it hurts the well-being of your entire social circle, including strangers."
The overall body of work from Walker and Simon encompassed three studies. The first analyzed the brain of 24 individuals with a functional magnetic resonance imaging (fMRI) scan after 8 hours of sleep and then again after a night of no sleep. It showed areas of the brain associated with empathy and understanding were less active after a sleepless night.
"When we think about other people, this network engages and allows us to comprehend what other person's needs are: What are they thinking about? Are they in pain? Do they need help?" Ben Simon said. "However, this network was markedly impaired when individuals were sleep deprived. It's as though these parts of the brain fail to respond when we are trying to interact with other people after not getting enough sleep."
The second phase was an observational study that tracked the sleep quality of more than 100 individuals and then measured that against how willing they were to help others in basic human interactions such as a stranger on the street or holding the elevator door open for someone else.
"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 prior were the ones that reported being less willing and keen to help others the following day."
The third study looked at the charitable giving of more than 3 million donations between 2001 and 2016 which showed a 10% decrease the week after Daylight Saving Time kicked in and people lost an hour of sleep. A similar drop was not seen in areas where clocks were not adjusted.
"Even a very modest 'dose' of sleep deprivation—here, just the loss of one single hour of sleep opportunity linked to daylight saving time—has a very measurable and very real impact on people's generosity and, therefore, how we function as a connected society," Walker said. "When people lose one hour of sleep, there's a clear hit on our innate human kindness and our motivation to help other people in need.
"A lack of sleep makes people less empathetic, less generous, more socially withdrawn, and it's infectious—there is contagion of loneliness," Walker added. "The realization that the quantity and quality of sleep affects an entire society, caused by an impairment in prosocial behavior, may provide insights into our societal state of affairs in the present day."