Participants reported feeling sensations related to ‘sex’ and ‘persecution’ more frequently than anyone else.
Among the other racy motifs that dreamt up were ‘being tied up’, ‘being locked up’ and ‘unable to move’.
Lead author Calvin Kai-Ching Yu from Shue Yan University in Hong Kong said that the increase in sexual thoughts could be because people don''t get as much air when they sleep on their stomach, so their mind was imagining being constricted when you sleep.
For the study he spoke to 670 students, two-thirds of whom were female, and asked them to fill out surveys about their dreams.
The details included how often they occurred, how intense they were and what were the themes that came up.
He also asked them to write down their sleeping posture, how often they slept on their sides, face down or face up.
Among the other ideas that came to people who slept on their front most frequently was ‘erotomania’, which is when a person believes they have a secret admirer, 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,” the Daily Mail quoted Kai-Ching Yu as saying.
“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 observe or are aware of.
“The unconscious brains of the dreamers try to make sense, and even make use of, the external stimuli,” he added.
The study was recently published in the journal Dreaming.