A Sleep Battle of the Sexes - WSJ.com: Most people regularly sleep with a partner, and some research has shown that people wake up more and have less deep sleep when they sleep with another person. Still, people generally say they are more satisfied with their sleep when they are with a loved one. "There are objective costs to the physical presence of someone else in the bed," says Wendy M. Troxel, an assistant professor at the University of Pittsburgh and a leading researcher on relationships and sleep. But "the safety and security we derive from our social relationships trumps the cost," she says.