The Truth About Wet Dreams: A Guide for All Wet dreams, known scientifically as nocturnal emissions, refer to the involuntary ejaculation that occurs during sleep. For individuals with a penis, this manifests as the release of semen, which contains sperm. Interestingly, those with a vagina can experience wet dreams too, often in the form of an orgasm during their slumber. This phenomenon is a natural aspect of human sexuality, transcending age and gender, and is something many individuals experience at different points in their lives.