Couples feel closer after indulging in unhealthy behaviours together

Most of us will be able to think of times we've engaged in problematic behaviours because it benefitted us and our social relationships in the short term. Perhaps you smoked a cigarette because your friend was having one, stayed for that one extra drink even though you should probably have gone home, or lounged on the sofa with your partner rather than going out because it just seemed easier.

A new study in Personality and Social Psychology Bulletin finds that engaging in these kinds of behaviours with a romantic partner can actually bring you closer. The study brings up interesting questions about how the rewards associated with problematic short-term behaviours might impact our ability to achieve healthier long-term goals.

Theresa Pauly at the University of Zurich and colleagues looked at data from three previous diary studies of unhealthy behaviour in couples. In the first, smokers recorded how many cigarettes they smoked together each day for a month. In the second, inactive and overweight couples wore accelerometers for four weeks to track periods in which they were sedentary together. And in the third study, participants were couples in which at least one partner had a history of stroke, who took pictures of their food intake each day to record how often they ate food high in fat, sugar or salt. In all studies, participants also rated their closeness and satisfaction with their relationship each day.

In the smoking study, participants reported higher levels of closeness and higher relationship satisfaction on days they shared cigarettes together. Similarly, in the second study, on days when partners engaged in greater shared sedentary behaviour, they reported higher closeness and relationship satisfaction. Importantly, the researchers also found that both satisfaction and closeness was higher the day after sharing cigarettes and being inactive, while the reverse wasn't true. This suggests that engaging in problematic behaviours together actually causes increases in relationship satisfaction.

In the final study, participants did not report any differences in closeness or satisfaction when they jointly consumed more unhealthy foods.

Overall, however, the study seems to suggest that shared problematic behaviours can foster closeness and satisfaction in the short-term, despite the fact that they are maintaining potentially unhealthy behaviours. Future research should look at how these behaviours affect our relationships in the long run. Even if there may be short-term social benefits, do we want to stay with a partner who encourages us to eat badly and smoke 20 cigarettes a day, or would we rather be with someone who encourages us to be healthy? Other research could also look at shared but different problematic behaviours. For example, would the same effect hold if one partner is a smoker while the other spends too much time watching TV?

Still, the study suggests that if we want to change our behaviours – or if doctors or other health professionals want to encourage us to do so – then it's important to consider broader relational structures such as families and romantic relationships and their role in our health.