When researchers conducted a study, participants who slept on their stomach reported erotic feelings and sensations associated to persecution. Some of them reported 'being tied up', 'being locked up' and 'unable to move'.
The increase in sexual thoughts could be due to decreased air when people sleep on their stomach. This could have caused the mind to go on a journey of imagination, with thoughts of feeling constricted or restrained.
This study does provide a clue about how body posture may influence the nature and content of dreams during sleep.
Source: Medindia
