She's an insomniac; she only sleeps for two or three hours a night.
她患失眠症, 每晚只睡两三个小时.
辞典例句
The insomniac is habitually afflicted with wakefulness at times when he wishes to sleep.
失眠症患者,这种病人在他想睡觉时经常特别清醒.
期刊摘选
"insomniac old people"
"insomniac nights"
"lay sleepless all night"
"twenty watchful, weary, tedious nights"- Shakespeare