National Sleep Foundation

Chapter 5: Circadian Rhythm Sleep Disorders

Etiology/Risk Factors

What are the Risk Factors for Irregular Sleep Wake Type (IST)?

Dysfunction of circadian regulation can lead to IST, such as in patients with neurological dysfunction and reduced exposure to external cues (e.g., light, activity, social schedule). These situations are commonly observed in retired, elderly, or chronically ill individuals.44 45


44. Pollak CP, Stokes PE. Circadian rest-activity rhythms in demented and nondemented older community residents and their caregivers. J Am Geriatr Soc. 1997;45:446-452.

45. Van Someren EJ, Hagebeuk EE, Lijzenga C, et al. Circadian rest-activity rhythm disturbances in Alzheimer's disease. Biol Psychiatry. 1996;40:259-270.