Restless nights, cold hearts: Poor sleep causally blunts empathy.

Poor sleep is pervasive in modern society. Poor sleep is associated with major physical and mental health consequences, as well as with impaired cognitive function. Less is known about the relationship between sleep and emotional and interpersonal behavior. In this work, we investigate whether poor sleep impairs empathy, an important building block of human interaction and prosocial behavior. We aimed to capture the effects of poor sleep on the various aspects of empathy: trait and state, affect and cognition. Study 1 (n = 155) assessed daily habitual sleep over several days, and global sleep quality in the past month. Participants who reported worse sleep quality exhibited lower empathic caring and perspective-taking traits. Study 2 (n = 347) induced a one-night disruption of sleep continuity to test a causal relationship between sleep and empathy. Participants in the sleep disrupted condition had to briefly wake up five times over the night, whereas the sleep-rested controls slept normally. In the next morning, participants' empathy and prosocial intentions were assessed. Participants in the sleep disruption condition exhibited lower empathic sensitivity and less prosocial decision-making than sleep-rested controls. The main contribution of this work is in providing a robust demonstration of the multi-faceted detrimental effects of poor sleep on trait and state empathy. Our findings demonstrate that poor sleep causally impairs empathic response to the suffering of others. These findings highlight the need for greater public attention to adequate sleep, which may impact empathy on a societal level.