Most of us have sat through a screening of the film Titanic, once, twice, or perhaps more times than we're willing to admit — with a box of tissues. Despite its being one of Hollywood's most tragic love stories, we continue to rewatch the tale of two star-crossed lovers meeting on the ill-fated boat. Now researchers at the University of Oxford suggest our masochistic movie tendencies have surprising benefits: boosts in social bonding, and our threshold for physical pain.

"But why should we be just as engaged by emotionally stirring plots that ‘reduce us to tears’ (i.e. tragedies)?" wrote the researchers, in the paper.

Previous research has found our enjoyment for comedy might stem from the fact that laughter activates the endorphin system, giving us a sense of reward and pleasure. Endorphins are feel-good chemicals secreted within the brain and nervous system affecting a number of physiological functions. They act as analgesics and increase the tolerance for pain. This is why comedy makes us laugh out loud and leads to an increase in our pain tolerance, but why do we keep repeatedly returning to tearjerker movies?

The researchers found watching a sad movie may harness the same system as comedies do. Films like Titanic boost feelings of social bonding, as well as increasing pain tolerance by upping endorphin levels in the brain. The emotional pain derived from watching tragedy — which is different from actually experiencing a tragedy in real life — triggers the endorphin system, which as a result, leads us to experience happiness.

In the study, published in the journal Royal Society Open Science, Robin Dunbar, co-author of the study and professor of evolutionary psychology at the University of Oxford, and his colleagues sought to explore whether our love for storytelling is underpinned by an endorphin-related bonding mechanism.

A total of 169 participants were recruited to watch Stuart: A Life Backwards , a made-for-TV film based on the true story of a disabled, homeless drug addict and alcoholic. A control group of 68 individuals were shown two documentaries back to back: an episode of The Museum of Life, a behind-the-scenes look at the Natural History Museum in London, and Landscape Mysteries “In Search of Irish Gold,” which explores Irish geology and archaeology.

Before and after watching the films, all the participants took two tests: One measured their sense of belonging or bonding with their fellow audience members. Another was a measure of pain sensitivity, called the Roman chair — a well-established proxy for endorphin release, according to Dunbar. In it, participants brace themselves unsupported in a chairlike stance against a wall until their leg muscles burn painfully. The higher a person’s endorphin level, the longer they should be able to sustain the posture.

The findings revealed those who had watched Stuart: A Life Backwards were able to maintain the Roman chair roughly 18 percent longer than they had in their initial baseline test, compared with those who had watched the documentaries. There was also a correlation between sad movies and a sense of social bonding that was not seen in the control group.

It's important to note the Roman chair pain sensitivity test did not directly measure endorphin release, which leaves the possibility for other factors to influence the increase in social bonding. For example, not everyone who saw the Stuart: A Life Backwards experienced an increase in their sense of bonding; it actually made them more sensitive to pain. This is not surprising since movies are subjective to individual taste.

A similar 2012 study in the journal Communication Research suggests we enjoy watching sad movies like Titanic because they deliver an unexpected emotion: short-term happiness. Watching a tragedy causes us to think about our own close relationships, which in turn boosts our life happiness. In other words, it seems that a negative experience can make us happier by making us more appreciative of the positive aspects in our own lives.

So, for those looking to have a good cry and boost social bonding here is our list of the five must-watch tearjerkers: Schindler's List; Titanic; Life Is Beautiful; The Notebook; and 12 Years a Slave .

Source: Dunbar RIM, Teasdale B, Thompson J et al. Emotional arousal when watching drama increases pain threshold and social bonding. Royal Society Open Science. 2016.