National Sleep Foundation

Chapter 5: Circadian Rhythm Sleep Disorders

Consequences

What are the consequences of Advanced Sleep Phase Disorder (ASPD)? 

Patients with ASPD often complain of extreme sleepiness in the late afternoon or early evening in addition to involuntary early morning awakening (2:00 to 5:00 am).28
In patients whose social or professional obligations to stay up late, chronic insufficient sleep and daytime sleepiness can occur due to these early morning awakenings.29

References

29.  Reid KJ and Zee PC. “Circadian disorders of the sleep-wake cycle,” in Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, 2011, pages 470-482.

30.  Reid KJ and Zee PC. “Circadian disorders of the sleep-wake cycle,” in Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, 2011, pages 470-482.