People who sleep on their belly are significantly more likely to have racy dreams compared to those dozing off in other positions, new research reveals.

Participants front-down admitted sensations of "sex" and "persecution" more often than others. They also reported dream themes like being tied up, locked up and unable to move, according to the paper published in the journal Dreaming.

Lead author Calvin Kai-Ching Yu from Shue Yan University in Hong Kong said the increase in sexual thoughts could be because people don't get as much air when they sleep on their stomach. This makes their unconscious brain think or imaging being constricted.

Researchers interview 670 university students, two-thirds female, and asked them about their dreams, Medical Daily reported.


They filled out details of how often they dreamt, how intense the dreams were and any themes. Participants also documented how often they slept on their side, their back and their front.

The most common theme that came up when people slept on their tummy was "erotomania" - when a person believes they have a sexual admirer who is often a famous person.

"This study provides the evidence that dream experiences, and in particular dream content, can be influenced by body posture during sleep," researchers concluded.

"I believe that the brain during sleep is not at all totally detached from the external world, and stimuli, including those stemming from the environment, are probably incorporated into dream content more often than people are aware of," Kai-Chang Yu told NBC News.

"The unconscious brains of the dreamers try to make sense, and even make us of the external stimuli."