Behaviorally and environmentally induced non-24-hour sleep-wake rhythm disorder in sighted patients

Study Objectives: To determine whether there was evidence of circadian or sleep-regulatory dysfunction in sighted individuals with non-24-hour sleep-wake rhythm disorder. Methods: Three sighted individuals with signs and/or symptoms of non-24-hour sleep-wake rhythm disorder were studied. Thirty-five- to 332-day laboratory and home-based assessments of sleep-wake and circadian timing, endogenous circadian period, photic input to the circadian pacemaker, and/or circadian and sleep- wake-dependent regulation of sleep were conducted. Results: No evidence of circadian dysfunction was found in these individuals. Instead, sleep-wake timing appeared to dissociate from the circadian timing system, and/or self-selected sleep-wake and associated light/dark timing shifted the circadian pacemaker later, rather than the circadian pacemaker determining sleep- wake timing. Conclusions: These findings suggest that the etiology of this disorder may be light- and/or behaviorally induced in some sighted people, which has implications for the successful treatment of this disorder.

Automated summary

This study found no evidence of circadian dysfunction in sighted individuals with non-24-hour sleep-wake rhythm disorder. Instead, sleep-wake timing appeared to dissociate from the circadian timing system, and the disorder may be light- and/or behaviorally induced.