**3.2 Delayed sleep-wake phase disorder (DSWPD)**

ICSD-3 Diagnostic Criteria [6]: A delay (late timing) in the phase of the major sleep episode in relation to the desired or required sleep time and wake-up time (i.e. the patient does not feel sleepy at bed time and wakes up too late).


Clinical Characteristics: DSWPD is one of the most common circadian rhythm sleep–wake disorders, often affecting adolescents and young adults when eveningness tendencies are typically the strongest. This is a defect of the circadian system whereby the sleep/wake cycle is misaligned with the patient's desired schedule by more than 2 hours. Individuals go to sleep and wake up at substantially later times than desired, which can lead to social consequences such as chronic tardiness at work or school. Delayed bedtimes (usually between 1 and 6 AM), coupled with early awakenings to meet social/occupational/academic obligations, result in a sleep debt that accumulates over time. There is often a high prevalence of comorbid depression, and higher degrees of circadian misalignment correlate with greater severity of depression.

The intrinsic circadian period is generally longer than normal. DSWPD typically emerges during adolescence and can continue into adulthood.
