National Sleep Foundation

Chapter 5: Circadian Rhythm Sleep Disorders

Prevalence

What is the prevalence of delayed sleep phase disorder (DSPD)?

The prevalence of delayed sleep phase disorder (DSPD) in the general population is unknown, but it is but is estimated at about .17 percent.  It is thought to occur most frequently in adolescents and young adults, with an estimated prevalence of 7 percent in this population.  
DSPS has been observed in between 6.7 and 16 percent of patients presenting to sleep disorders clinics with a primary complaint of insomnia.

References

5. 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.

6.  Pelayo RP, Thorpy M, Glovinsky P. Prevalence of delayed sleep phase syndrome among adolescents. J Sleep Res. 1988;17:392.

7. Regestein QR, Monk TH. Delayed sleep phase syndrome: a review of its clinical aspects. Am J Psychiatry. 1995;152:602-608.