(名詞) 睡覺中從事性行為的睡眠疾病。顯然地,這個字是由 sex 和 insomnia (失眠症) 拼綴而成。
sexsomniac (名詞):睡覺中從事性行為的睡眠疾病患者。Cf. insomniac (名詞):失眠症患者。

有人對於 sexsomnia 的中文解釋「睡覺中從事性行為的睡眠疾病」可能無法完全瞭解其真正的意思,甚至可能質疑睡覺時要怎麼嘿咻呢? 誠然,這裡所謂的睡覺中其實是指患者處於夢遊狀態。根據研究人員所拍攝的實境影片,患者白天一切正常,毫無異狀,但當他們或她們睡著後,他們或她們經常變成「性瘋狂」或「性飢渴」的怪獸,以粗暴的方式撕破太太、先生或同居人的衣物,霸王硬上弓。然而,每天睡醒後,患者對於他們或她們所做過的事卻一點都不記得。

The phenomenon, called sexsomnia, is a form of parasomnia, a disorder in which people who are asleep but in a state of semi-arousal engage in behaviors they are not conscious of. Sexsomnia is defined by the International Classification of Sleep Disorders and may take place during a sleepwalking episode.
—Roni Caryn Rabin, "No Sex, Please: You're Sleeping," The New York Times, June 8, 2010

It's hard to believe, but sexsomnia — making advances and performing sexual acts while in the grip of sleep — appears to be more common than once thought. Researchers have found almost 8 per cent of patients at a Toronto sleep clinic reported they initiated or engaged in sexual activity with a partner while asleep. The prevalence of sexsomnia was almost three times higher in men (11 per cent) than in women (4 per cent).
—"Sexsomnia found more often in men," The Hamilton Spectator, June 7, 2010