National Sleep Foundation

Chapter 5: Circadian Rhythm Sleep Disorders


What is the Treatment for Irregular Sleep Wake Type (IST)?

Treatment is designed to improve the amplitude of the individual’s circadian rhythm and their alignment with external cues.
Consolidation of sleep-wake cycles has been effectively achieved using bright light therapy48 and structured social and physical activity (i.e., from 9:00 AM to 10:30 AM and 7:00 PM to 8:30 PM daily for two weeks).49

In one study, 45 percent of patients showed improvement when treated with a combination of bright light therapy, vitamin B12, chronotherapy, and hypnotics.50 It is important to note that the use of hypnotics increases the risk of hip fractures and other injuries from falling.


48. Ancoli-Israel S, Martin JL, Kripke DF, et al. Effect of light treatment on sleep and circadian rhythms in demented nursing home patients. J Am Geriatr Soc. 2002;50:282-289.

49. Naylor E, Penev PD, Orbeta L, et al. Daily social and physical activity increases slow-wave sleep and daytime neuropsychological performance in the elderly. Sleep. 2000;23:87-95.

50. Yamadera H, Takahashi K, Okawa M: A multicenter study of sleep-wake rhythm disorders: Clinical features of sleep-wake rhythm disorders. Psychiatry Clin Neurosci. 1996;50:195-201.