Married and single people describing themselves as lonely, left out, and isolated are also less likely to sleep well, according to a study published in the journal Sleep.

In this latest study on sleep patterns among the lonely, researchers polled
95 people in South Dakota about loneliness, depression, anxiety and stress levels. To gauge how well they slept, for one week participants wore a wristwatch-like device that recorded their movements. Those who participated were between the ages of 19 and 84, and most were married.

The study found a higher incidence of sleep disruptions among those who were lonely, even after controlling for age, size, sleep disorders and other factors that could affect sleep patterns. Surprisingly, the lonely people also were more likely than the depressed, anxious or stressed-out participants to believe they slept well, researchers found.

The sleep problems noted in this study may help explain a previously discovered link between loneliness and an increased risk of certain health problems, such as heart disease and dementia, says lead researcher Lianne Kurina, an assistant professor of epidemiology at the University of Chicago.