A clinical study suggests adults who share their beds with a partner have less severe insomnia, less fatigue, and get more sleep time. They also report being more satisfied with their lives and relationships, as well as having lower levels of stress, depression, and anxiety.

Researchers used data from 1,007 working-age adults in Pennsylvania, and found that people who slept with an adult partner fell asleep faster, stayed asleep longer, and had less risk of sleep apnea. Those who slept in the same bed as their child had higher odds for sleep apnea, more severe insomnia, and less control over their sleep.

Reasons for the findings are speculative, but Michael Grandner, director of the Sleep and Health Research Program at the University of Arizona in Tucson suggested that safety or socialization may be at their root.

“There might be some evolutionary advantage that humans have benefited from for most of our existence, but we don’t really take advantage of anymore because we’re not all camping around the fire, seeing if a predator’s going to wander into our camp, but maybe that machinery is still there and there’s a drive towards not being alone when we’re vulnerable and asleep,” Gardner said.