When Professor Antonio Zadra began investigating nightmare narratives he expected to hear about chases. Lots and lots of chases. In fact, the stories were considerably more varied and interesting (one simply involved a large, ominous owl).

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, and found big differences in men's and women's nightmare scenarios.

Themes of interpersonal conflict were twice as frequent in women's nightmares as men's, while men were much more likely to report nightmares involving disaster or calamity, such as floods, earthquakes or wars.

This isn't the first time gender disparities have been noticed in dream states, says Zadra. 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". He doubts the methodology behind studies that have shown highly specific scenarios such as weddings and domestic chores occurring more frequently in women's dreams, sports and cars in men's, but says that, more broadly, interpersonal themes do get "portrayed metaphorically more often in women's dreams. And 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. Whereas the men's dreams, really, 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."

Don't let the Ominous Owl keep you up at night. Photograph: Ian Jeffery

Thematic gender differences also arise in sex dreams. Zadra has been carrying out a study into this area, not yet published, and says, "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 – a colleague, or something of that nature. 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 says he's a firm believer in the idea that dreams are an extension of our waking state. His study notes that women report far more nightmares than men, and he has three arguments to explain this. One is that women, in general, experience higher rates of depressive and anxiety disorders, and nightmares tend to occur in times of stress. There's also evidence that women have much better dream recall than men, "so it could just be that they remember more of their nightmares as well".

And there's a chance that gender stereotypes in our waking lives affect what we admit about our dream lives. "It's possible," says Zadra, "that some men don't want to admit to having nightmares, so they intentionally lie about their frequency."