The whole "don't go to bed angry" adage really is a nice thought. No one wants to stew over an argument from the other side of the bed when there could be plenty of spooning—or, let's be honest, makeup sex—instead.
Except, well, science might suggest otherwise. Turns out, sleep-deprived fighting with your partner may actually be harmful to your long-term health, according to a new study published in Psychoneuroendocrinology. This research suggests that 1) fighting with your partner plus 2) sleep deprivation equals 3) an increase in stress-related inflammatory responses—which have been linked to higher risk of cardiovascular disease, diabetes, and arthritis.
The study looked at 43 married couples during two separate lab visits. At each visit, the couples provided blood samples and reported how many hours they'd slept the previous two nights. Then, the researchers lit a fire: They instructed the couples to try to resolve a topic that sparks conflict (in-laws, $$$, politics, that too-friendly ex) in their relationship. (We know, savage.) Then researchers took more blood samples after the discussion.
What they found: Couples who were short on sleep had a greater inflammatory response to the conflict. If both partners got fewer than seven hours of sleep during the previous two nights, the couple was more likely to argue or become hostile. And for every hour of sleep lost, levels of two specific inflammatory markers rose by 6 percent. (More bad news: Relationship stress can make you gain weight.)
The good and bad news is that how you fight matters. Couples who used unhealthy tactics in their disagreement had an even greater inflammatory response—about a 10 percent increase with each hour less sleep. But pairs who calmly and effectively resolved the conflict—by better expressing and reappraising their emotions—had lower levels of inflammation after the discussion.
The easiest fix? Getting more shut-eye. Researchers found that more sleep made the conflicts less impactful on inflammation levels, even if just one partner had adequate sleep. (Also, puppies. They're apparently the secret to a happy relationship.)
Obviously, one late-night, heated discussion about your in-laws isn't going to make you wake up with heart disease and diabetes—but a chronic lack of sleep, plus anything that causes stress (whether it's from your SO, your job, your frenemy, etc.) is where this could be a real threat to your health. "What we worry about in a study like this is having even a relatively modest change in inflammation, but persistent over time," said Janice Kiecolt-Glaser, Ph.D., director of the Institute of Behavioral Medicine Research at Ohio State Wexner Medical Center (where the study was done), in a release. "If this is a pattern, and if couples don't find ways to effectively address their differences, having continuously elevated levels of inflammation could put them at a higher risk for a wide range of diseases."
The best news of all, though: You can crush stress, decrease your risk for those diseases, and improve your relationship by working out together. All the more reason to get sweaty.