Having issues with your spouse? Lack of sleep could be part of the problem. According to a recent study highlighted in the New York Times, couples who got less than 7 hours of sleep per night were more likely to be hostile towards one another than partners who slept for 7 or more hours a night.

For the study, published in May in the journal Psychoneuroendocrinology, researchers asked 43 couples to talk about the biggest issues in their marriage on camera. The researchers analyzed the footage and noted the positive and negative emotions displayed by the couples (married for anywhere between 3 and 27 years) and whether they approached their problems in a constructive or hostile way.

The topics the couples argued about ranged from finances to in-law issues to kids’ birthday parties (hey, they’re more stressful than you think), and while every couple had differences, the way they talked about them varied greatly. And a distinct pattern emerged: couples who reported getting fewer than 7 hours of sleep per night were more hostile towards each other when they discussed their issues. Though couples who reported getting more than 7 hours of sleep weren’t immune to arguing, they were more likely to approach difficult conversations with kindness and humor.

“When people have slept less, it’s a little like looking at the world through dark glasses,” Janice Kiecolt-Glaser, study author and director of the Ohio State Institute for Behavioral Medicine Research told the New York Times. “Their moods are poorer. We’re grumpier. Lack of sleep hurts the relationship.”

As if troubles with your partner aren’t concerning enough, the study also found that after a night with less than adequate sleep and less than loving conversations, partners also had higher levels of inflammation, which is linked to a list of health issues including cancer and heart disease. (The researchers measured this via blood samples.) As Kiecolt-Glaser said to the New York Times, “Lack of sleep not only hurts the relationship, it makes relationship conflict harder on the body.”

Thankfully, the study’s lead author, Stephanie Wilson, noted that when one half of a couple gets enough sleep, it can make all of the difference. “When one person was rested, it protected the couple from being more nasty to each other,” Wilson said to the New York Times.

It’s hard to control how much sleep your partner gets, but ensuring that you get a full 7 to 9 hours a night could help keep disagreements from crossing the line from constructive to unhealthy. And next time you’re thinking about bringing up a touchy topic, make sure that you’re well rested enough to have a productive conversation about it. Your partnerand your body—will thank you.

Read more about the study in the New York Times.