Complex sentence: Sleep sex, or sexsomnia, is a condition in which a person will do sexual acts while still asleep, acts such as masturbation, fondling themselves or others, having sex with another person and in more extreme cases sexual assault or rape.
Split into simpler sentences: Sleep sex, or sexsomnia, is a condition in which a person engages in sexual activity while asleep. While still asleep people with sexsomnia do things such as masturbation, fondling themselves or others, having sex with another person and also, sometimes, seriously problematic actions such as sexual assault or rape.