National Sleep Foundation

Chapter 5: Circadian Rhythm Sleep Disorders


What is the prevalence of advanced sleep phase disorder (ASPD)?

ASPD’s prevalence in the general population is unknown, but it is believed to be rare. It occurs in about one percent of middle-aged adults, and appears to increase with age; this is particularly true for those were “early birds” when they were younger.26  
Both sexes are equally affected.27


26. Ando K, Kripke DF, Cole RJ, Elliott JA. Light mask 500 lux treatment for delayed sleep phase syndrome. ProgNeuropsychopharmacolBiol Psychiatry. 1999;23:15-24.


27. Wagner DR. Disorders of the circadian sleep-wake cycle. NeurolClin. 1996;14:651-670.