We’re selfish when we’re sleep-deprived, which has real-world consequences

Wake up on the wrong side of the bed one morning? Research says that lack of quality sleep can not only make you less social and more selfish, but also that grumpiness can be felt throughout society. Scientists have found that lack of sleep is associated with increased health risks, such as cardiovascular disease, depression, diabetes, hypertension, and a shorter lifespan—and now, a less empathetic society, too.

The Helen Wills Neuroscience Institute at the University of California Berkeley conducted multiple studies that found those who were sleep-deprived showed a decreased natural instinct to help others. Lead research scientists Eti Ben Simon and Matthew Walker looked primarily at the functional magnetic resonance imaging (fMRI) of people after eight hours of sleep and those with no sleep and assessed the subjects’ level of selflessness and empathy toward others. Here’s what the study uncovered: 

Lack of sleep impairs the theory of mind network. fMRI’s showed that the theory of the mind network, the part of the brain that lights up when we’re feeling sympathetic, was less active in those 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,” said Ben Simon.
Sleep loss affects us and those around us. Sleep-deprived people were more likely to be socially disengaged, lonely, and isolated. “Worse still, when those sleep-deprived individuals interacted with other people, they spread their loneliness to those other individuals, almost like a virus,” said Walker.
We’re less generous when we don’t sleep. Researchers reviewed 3 million charitable donations between 2001 and 2016, comparing American states that transitioned to daylight savings time with those that didn’t, and found a 10% drop in donations for states that changed their clocks. 

Our sleep deprivation has a ripple effect across our broader social society. According to Walker, “Even a very modest ‘dose’ of sleep deprivation has a very measurable and very real impact on people’s generosity and, therefore, how we function as a connected society.”