Two-thirds (PDF) of U.S. adults report that they regularly sleep with a partner. Yet, through 60 years or so of sleep research, scientists have tended to view sleep as an individual behavior, largely ignoring the potential impact of bedmates. This has led to numerous tired myths about the impact sleeping together can have on couples' emotional, physical and relational health.
1. Sex is good for sleep.
Perhaps the most widely held and rarely challenged myth about sleeping together is that sex helps couples fall asleep more quickly and deeply. It's not exactly clear where this myth comes from. Perhaps it evolved over time as the counterargument to “Not tonight, dear. I'm too tired.” The lack of hard evidence for this one is striking, unless you count lab experiments that documented the soporiferous effects of rat sex. Yet, like most myths, this one has a basis in fact and with further research it might one day be found to be true.
There are several biological changes that occur during orgasm that might enhance sleep, including the release of relaxation-promoting hormones, such as prolactin, oxytocin and vasopressin. And incidentally, some of these biological changes are more likely to occur following orgasms achieved with another than those reached solo. My colleagues and I are particularly interested in examining the hormone oxytocin's role in promoting sleep for both men and women, given that oxytocin is well-known for promoting “pair-bonding” and may provide an evolutionary basis for why humans generally prefer to sleep with a partner.
2. Larks and owls just can't get along.
Night owls burning the midnight oil and morning larks cheerfully rising at the crack of dawn are generally more likely to flock together, but that doesn't mean those from opposite sides of the circadian spectrum cannot successfully share the same nest.
There is some evidence from cross-sectional studies that mismatched couples do have higher rates of relationship problems, including conflict, lower relationship satisfaction and intimacy challenges. But given the cross-sectional nature of the data, it is still unknown whether differences in their morning-evening preferences caused their relationship woes, or whether their schedules diverged as a means of avoiding the offending partner.
Research has also found that mismatched couples (PDF) that share strong problem-solving skills are at no greater risk for relationship problems than couples whose sleep schedules are more in sync. In other words, couples who know how to work together to solve problems are able to negotiate their differences and reach compromise both day and night, which is a key factor in all healthy and happy relationships.
3. Sleeping apart leads to failed marriages.
Lucy and Ricky Ricardo slept in separate beds every night and their marriage was one of television's most enduring. So what's so bad about couples sleeping separately? Nothing, really. My research focuses on the links between healthy relationships and healthy sleep habits, but these findings are often misinterpreted to suggest that sleeping together is necessary for healthy marriages and that sleeping apart is a sure sign of looming relationship doom. The truth is there is no one-size-fits-all approach to couples' sleeping arrangements, and forced adherence to socially sanctioned norms, such as the “marital bed,” may cause its own problems.
Most couples do tend to prefer sleeping together, but for others, sharing a bed can mean sleepless nights for one or both partners. This can produce greater relationship stress. In fact, our research has shown that for men, having a poor night's sleep was associated with diminished relationship functioning the next day. Just as larks and owls can get along when there is good problem solving in the mix, couples who make conscious and collaborative decisions to sleep apart are perfectly capable of maintaining intimacy and highly satisfying relationships.
4. Snoring is just a nuisance.
It's an all too common scenario. He falls asleep, the snoring begins, she lies in bed cursing him, and in exasperation, gives him a fierce jab to his ribs to stop the incessant, sleep-defying clamor. And the sonic assault can come from either side of the bed. Although men are more frequently fingered as the source of all snoring evils, women also saw their share of wood.
The dangers associated with snoring go well beyond an occasional elbow to the ribs or a pillow to the head. It is now well-recognized that snoring is a cardinal symptom of obstructive sleep apnea, which may foretell serious health consequences including increased risk for heart disease and stroke.
There also is evidence to suggest that the vibrations caused by snoring in the neck might have a direct impact on the development of atherosclerosis, the process underlying the development of heart disease. And all those long-suffering bedmates? They face health risks too. Research has shown that women living with snorers were three times as likely to report symptoms of insomnia compared to women living with silent sleepers. So do your sleep partner and yourself a favor and get some help.
5. Never go to bed angry.
We've all heard the old adage “never go to bed angry.” Makes sense, right? Well, not necessarily. There is evidence that negative emotional states, such as anger, stress or depression, can interfere with good quality sleep, but there is very little evidence showing how these stressors affect feuding couples' sleep.
In 2011, researchers Angela M. Hicks and Lisa M. Diamond found that although couple conflict did cause sleep disruption, anger itself did not. “The correct adage is not 'don't go to bed angry,' but rather, don't fight before bed,” the authors said.
Our work has also shown, that for women, higher levels of conflict during the day predicted poorer sleep for both herself and her husband that night. But where this myth can really lead couples astray is making them think that they should stay up to try and douse the flames of conflict because, well, that's just not going to work. Many problems faced by couples simply cannot be fixed in time for bed. Choose your battles and the timing of those battles — a fight before bedtime is unlikely to be resolved and may rob you both of sleep.
Wendy Troxel is a clinical psychologist and behavioral scientist at the nonprofit, nonpartisan RAND Corporation and an adjunct assistant professor at the University of Pittsburgh, Departments of Psychiatry and Psychology.
This commentary originally appeared on The Huffington Post on February 14, 2014. Commentary gives RAND researchers a platform to convey insights based on their professional expertise and often on their peer-reviewed research and analysis.