Nobody likes being lonely. As it turns out, loneliness can also be unhealthy. The study was done by psychologist John Cacioppo at the University of Chicago. He had thirty three male college students and twenty one female students spend five nights in a lab where their sleep could be carefully monitored.

This was accomplished by having them catch Z's while wearing a special skull-cap that had devices for measuring eye motions, head motions, and brain waves. Why? Because different kinds of waves are generated by your brain as you sleep, and the motions of your body--especially your eyes--give information about how your sleep is going.

Afterward, the students filled out a questionnaire describing themselves. In particular Cacioppo wanted to know what their social lives were like, to see if there was any connection between your social life and how well you sleep. There was indeed a connection. Everyone slept for about the same amount of time, but the volunteers who rated themselves as the loneliest were also the ones who were most likely to wake up during the night. Not only that, they stayed down in deep sleep less than other people did.

What do these findings mean? The researchers themselves note that it isn't clear yet which is the cart and which is the horse. That is, does being lonely interfere with a healthful night's sleep? Or, on the other hand, do people who sleep poorly for one reason or another wind up irritable and difficult to deal with, making it harder to have friends? One way or the other, lonely feels bad--and sleep shows it.