Delayed sleep phase disorder (DSPD), officially called circadian rhythm sleep disorder, delayed sleep phase type, is an inability to fall asleep at a desired, conventional clock time and awaken at a socially acceptable morning time. When allowed to choose their preferred sleep schedule, patients exhibit sleep of normal quality and duration for their age and maintain a stable but delayed relationship of entrainment to the 24-hour, sleep-wake pattern.1-2
Fig 5.1 Advanced and delayed sleep phase
- American Academy of Sleep Medicine. The international classification of sleep disorders: diagnostic and coding manual. 2nd ed. Westchester, Ill: American Academy of Sleep Medicine; 2005.
- Weitzman ED, Czeisler CA, Coleman RM, et al. Delayed sleep phase syndrome: a chronobiological disorder with sleep onset insomnia. Arch Gen Psychiatry. 1981;38:737-746.
- Reid KJ and Zee PC. Circadian disorders of the sleep-wake cycle. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. 4th ed. Philadelphia, Pa: Elsevier Saunders; 2005:693.Pelayo RP, Thorpy M, Glovinsky P. Prevalence of delayed sleep phase syndrome among adolescents. J Sleep Res. 1988;17:392.