If you want a happy marriage, get enough sleep. This advice is dispensed in marriage columns everywhere, with good scientific backing. Poor sleep makes couples fight more, and marital strife results in poorer sleep.
Beyond the strict number of hours couples spend conked out each day, though, new research from the journal SLEEP suggests another significant sleep-related indicator of a healthy marriage exists: the number of hours (and minutes and seconds) couples spend conked out together, side by side, in dreamland.
The study, led by University of Pittsburgh sleep researcher Heather Gunn, followed 46 married heterosexual couples for 10 days, measuring their sleep patterns minute-by-minute and evaluating each partner’s sense of marital satisfaction. On the whole, the couples were highly synced: Their sleep overlapped an average of 75 percent of the time, which—no surprise—is more than the overlap of any two random people, according to Gunn.
Lovebirds not only pick up each other’s habits, but their breathing and heartbeats actually align, according to two recent studies.
But where each couple fell relative to this average depended on one key factor: how happy the wife was with the marriage. Satisfied women mirrored up to almost 90 percent of their husbands’ sleep time, while dissatisfied wives spent as little as about half their time awake while their husbands slept or vice versa.
These results line up with previous work that has suggested women are especially affected by sleeping partners. Research by Wendy Troxel, one of the new study’s other authors, found that women in long-term relationships slept better than single women. Men’s sleeping patterns, for better or worse, aren’t as powerfully affected by the quality of their relationships.
“Most of what is known about sleep comes from studying it at the individual level; however, for most adults, sleep is a shared behavior between bed partners,” says Gunn in a press release. “This [study] suggests that our sleep patterns are regulated not only by when we sleep, but also by with whom we sleep.”
Part of the conclusion, of course, is totally obvious. Couples who are happy together presumably want to spend more time with each other, so it’s no surprise their schedules better align. But the minute-to-minute nature of their synchronization gets at something deeper about the science of human coordination that’s, well, sort of romantic. Lovebirds not only pick up each other’s habits, but their breathing and heartbeats actually align, according to two recent studies. We’re built to match in ways we’re not even aware of.
