Anyone who's been in a long-term relationship knows that sex and desire can wane over time, even as you feel more emotionally intimate with the other person.

According to a new study, though, there's a relatively easy way to bring the spark back.

As spotted by Psychology Today, a recent paper in the Journal of Social and Personal Relationships examines the concepts of closeness, otherness, and self-expansion — in other words, the emotional intimacy partners feel, the feeling of learning something new about one's partner, and the act of sharing new experiences with a partner.

According to the study, conducted by psychology researchers at Toronto's York University, emotional closeness alone isn't enough to sustain sexual desire in long-term relationships (the median relationship length in the cohorts studied was nine years.) To boost desire, they found, partners need to re-establish otherness, or a psychological distancing that allows them to see their significant other in a new light.

That sense of otherness can be achieved, the Canadian researchers found, via undertaking self-expansion together. Couples can make that happen a number of different ways, from going dancing together or visiting new attractions to probing each others often-unshared opinions about big life issues. Basically, the trick seems to be for couples to insert themselves into novel and challenging situations to regain a sense of freshness.

To be fair, the examples listed in Psychology Today are somewhat normie, which reflects the study's three test subject cohorts, which were overwhelmingly white and straight. But it's not hard to come up with alternative options to fit each individual couple. The "visiting new places" example in particular is ripe with possibility, especially considering the psychological research backing up the widely-believed concept that vacation sex really is better.

One of this paper's authors, York University researcher Amy Muise, also worked on a study last year that found the benefits from self-expansion can be boosted by planning and following through with date ideas. That might sound like a chore, but in practice, per the researchers' findings, it can lead to the feeling of shared newness that gets the fires burning.

While sex and relationships are both topics that vary wildly from person to person, a blueprint for how to navigate relationships after the initial honeymoon phases could be helpful for a range of relationships — and this research-backed advice is so simple, it certainly doesn't hurt to try.