It's often seen as a taboo subject.
But a new study is finally lifting the lid on sexual fantasies - and what they might say about you.
Scientists from Michigan State University analysed the frequency and variety of more than 5,000 people's sexual fantasies.
Their results revealed surprising associations between the participants' deepest desires and their personality traits.
If you experience frequent sexual fantasies, you probably have a more neurotic personality or may suffer from depression, according to the study.
In contrast, if you rarely find your mind wandering, you're more likely to be relatively conscientious or agreeable.
'People high in negative emotionality might engage in sexual fantasies as an emotion regulation tool to compensate for negative mood,' they explained in their study.
'Agreeable people may be less likely to sexually fantasize because of their respect for norms and others.'
One of the main categories is impersonal sexual fantasies (e.g. watching others have sex).
Sexual fantasies are rarely discussed, largely due to the stigma and embarrassment surrounding them.
As a result, there has been little research to examine how common they are, who is most likely to have them, and if the types of fantasies vary.
To get to the bottom of it, the researchers enlisted 5,225 adults, who were quizzed about the nature and frequency of their sexual fantasies.
Broadly, the fantasies could be placed into four main categories - exploratory sexual fantasies (for example, participating in an orgy), intimate sexual fantasies (e.g. making love outdoors in a romantic setting), impersonal sexual fantasies (e.g. watching others have sex), and sadomasochistic sexual fantasies (e.g. being forced to do something).
The participants also completed surveys to assess their levels of the 'Big Five' personality traits: openness, conscientiousness, extraversion, agreeableness, and neuroticism.
An analysis of the results revealed a link between some of the personality traits and sexual fantasies.
Participants who scored high in conscientiousness and agreeableness were found to report less frequent sexual fantasizing across all four categories.
'Agreeableness and conscientiousness are associated with norm endorsement, harm prevention, and traditionalism,' the researchers explained in their study published in PLOS One.
People with a high neuroticism score - in particular those with more depressive personalities - reported more frequent sexual fantasies.
The 4 main types of sexual fantasy
- Exploratory sexual fantasies (for example, participating in an orgy)
- Intimate sexual fantasies (e.g. making love outdoors in a romantic setting)
- Impersonal sexual fantasies (e.g. watching others have sex)
- Sadomasochistic sexual fantasies (e.g. being forced to do something)
'Thus, it seems reasonable to assume that they might be less likely to engage in fantasies that are non-traditional, bridge social norms, or simulate consensual aggression.'
Meanwhile, people with a high neuroticism score - in particular those with more depressive personalities - reported more frequent sexual fantasies.
'The fact that depression was strongly related to sexual fantasy - and that anxiety and emotional volatility were not - provides support for the possible emotional regulatory function of sexual fantasies,' the team added.
The researchers hope the findings will support 'more informed, sex-positive conversations'.
'Future work should continue refining these associations and examine whether personality dynamics predict changes in fantasy over time or across relational contexts,' they concluded.
The study comes shortly after researchers from Indiana University Bloomington uncovered what people enjoy most about sex.
A survey of more than 4,000 people revealed 22 main reasons, ranging from 'kink and pain' to 'children and procreation'.
While you might think that 'orgasm' would top the list, surprisingly, this wasn't the case.
What people love the most about sex
- Closeness/intimacy
- Specific sex acts
- Feels good
- Pleasing partner
- Love/caring
- Orgasm
- Arousal/excitement
- Calming
- Desire/Passion
- Enlivening
- Fun/Adventure
- Thrill/Rush
- Novelty
- Feeling alive
- Bodies and primal urges
Instead, the number one thing that people said they love about sex is closeness/intimacy, according to the study.
'Intimacy-related responses were the most prevalent,' the researchers wrote in their study published in the Journal of Sex & Marital Therapy.
'Participants wrote about feeling "lost in the moment" (57-year-old white bisexual woman), "overwhelming feelings of closeness" (a 50-year-old white lesbian woman) and "the feeling of the world not existing. Just the two of us is all that matters" (42-year-old Hispanic bisexual woman).'