When Professor Antonio Zadra began investigating nightmare narratives, he expected to hear a lot about chases.
But the stories were considerably more varied and interesting - one simply involved a large, ominous owl - and revealed some intriguing differences between the way men and women have bad dreams.
For a study just published in the journal Sleep, Zadra and co-author Genevieve Robert, of the University of Montreal, collected 9,796 dream reports, written by 572 participants over the course of two to five weeks. Themes of interpersonal conflict were twice as frequent in women's nightmares as men's, while men were more likely to report nightmares involving disaster or calamity, such as floods or wars.
Zadra said it wasn't the first time gender disparities have been noticed in dream states. In the past, it's been reported that women's dreams are more likely to take place indoors, and "men's dreams tend to contain more aggression than women's".
Also, for women, even a nightmare in full swing will frequently include a helping character, while men tend to navigate their dystopian dreamscapes alone.
Zadra said he doubted the methodology behind studies that had shown highly specific scenarios such as weddings and domestic chores occurring more frequently in women's dreams, sports and cars in men's. But more broadly, interpersonal themes do get "portrayed metaphorically more often in women's dreams".
"I think that's why, in their nightmares, they're more likely to be having these really nasty arguments, or being degraded or humiliated by people who exist in their real lives," Zadra said.
"In the men's dreams, it's war, calamities, infestation of insects - and they're usually alone. They're usually battling these things, and it doesn't often end well, but they're not in a social context, with people they know."
Thematic gender differences also arise in sex dreams. Zadra has been studying this area and said "by and large most of women's sexual dreams are either with their current life partner, a past partner, or someone they know in real life".
"In men's dreams, their current and past partners rarely figure. Instead, the characters they tend to dream about are entirely invented, people who do not exist. So it's not even that they're dreaming of a movie star."
It's not really surprising to find gender differences in our dreams, given that they're so encouraged in our daily lives - Zadra said he was a firm believer in the idea that dreams were an extension of our waking state.
His study also noted women reported far more nightmares than men, but Zadra said: "It's possible some men don't want to admit to having nightmares, so they intentionally lie about their frequency."
Additional reporting by Slate magazine