睡眠相位后移症候群（Delayed sleep-phase syndrome(Disorder)，简称DSPS或DSPD）是一种慢性睡眠紊乱，患者一般都会晚睡晚起，生活节奏受严重影响。

在临床诊断中，部分患者要到等至天亮才能入睡，一旦睡着，睡眠时间却跟正常人相约。除了一些患有睡眠呼吸中止症等睡眠障碍的患者外，他们的睡眠质量大多正常，然而这种晚睡晚起的状态，令人难以按时上班上课，扰乱作息时序。

此症常在儿童期或青春期出现，一些人的zh-hans:症状会随年纪增长而消失，但一些人却终生受此症困扰。外国一些研究指每2000人约3人会患上此症，占人口比例约0.15%，男女患者数目相约；而长期受失眠困扰的病人中,约7-10%患有此症。

Delayed sleep-phase disorder (DSPD), also known as delayed sleep-phase syndrome (DSPS) or delayed sleep-phase type (DSPT), and in the 2014 revision of the International Classification of Sleep Disorders (ISCD-3), delayed sleep-wake phase disorder, is a chronic dysregulation of a person's circadian rhythm (biological clock), compared to the general population and relative to societal norms. The disorder affects the timing of sleep, peak period of alertness, the core body temperature rhythm, hormonal and other daily cycles. People with DSPD generally fall asleep some hours after midnight and have difficulty waking up in the morning. People with DSPD probably have a circadian period significantly longer than 24 hours. Depending on the severity, the symptoms can be managed to a greater or lesser degree, but there is no known cure.