**3.1 Advanced sleep–wake phase disorder (ASWPD)**

ICSD-3 Diagnostic Criteria [6]:


Clinical Characteristics: ASWPD is an intrinsic defect of the circadian system in which sleep duration and quality are normal, but where sleep and wake up times are earlier than desired or socially acceptable. Generally, the intrinsic circadian rhythm period is actually shorter than normal.

Patients with ASWPD often report that they are unable to stay awake past 7 PM and tend to wake up around 2-5 AM. If a patient is able to set their own schedule they will obtain adequate sleep and feel refreshed in the morning. However, since due to social obligations they often stay up later than naturally desired while still waking early. This can lead to a sleep deficit over time that leads to daytime sleepiness.
