Sleep-deprived people are more selfish and lonely.

As a habitual night-owl, it pains me to consider this Scientific American interview with UC Berkeley neuroscientist Eti Ben Simon, whose research has shown that people who don’t get at least seven hours of uninterrupted sleep are less generous and less friendly. Every year when standard time switches to daylight savings, charities note a 10 percent drop in donations – but that’s not all:

People are less interested in social interaction when they’re sleep-deprived. For example, we designed a task where an experimenter and participant would face each other, and they would walk toward each other. The participant would decide when someone got too close, and we would measure that distance. Consistently, when people were sleep-deprived, they preferred others to be farther away.

We’ve also found that sleep deprivation reduces activity in what’s known as the theory of mind network in the brain. These are areas that help us think about other people—what they might want, what they’re like, and how they are similar to or different from ourselves.

In one study, just a one-minute video clip of someone talking was enough for others to pick up that they didn’t want to interact with a sleep-deprived person.

Sleep deprivation can make people feel lonely, and we’ve found that when people come into contact with someone who is sleep deprived, they report feeling lonelier after that interaction. I like to say that helps settle the Beatles’ question: “All the lonely people, where do they all come from?” It all started with sleep loss.

More seriously, I worry about a negative feedback loop with loneliness. If you’re chronically sleep-deprived, that feeling of not connecting can just keep increasing. You’re more withdrawn, less interested in interacting with others, and we’ve shown that others are less interested in interacting with you.

You can read more of Simon’s research here, in Trends in Cognitive Sciences, and here, in PLoS Biology.