Circadian-Based Therapies for Circadian Rhythm Sleep-Wake Disorders

This review summarizes recent developments relevant to the treatment of circadian rhythm sleep-wake disorders. The clinical practice guidelines for the treatment of intrinsic circadian rhythm sleep-wake disorders are described, followed by recent treatment studies for delayed sleep-wake phase disorder, non-24-hour sleep-wake disorder, irregular sleep-wake disorder, and shift work. New methods to estimate circadian phase, including home saliva collection to estimate the dim light melatonin onset, circadian questionnaires, and general rules to guide light and exogenous melatonin treatments, are described. New developments in light treatment are detailed, including light flashes during sleep and wearable light devices. Substances such as caffeine and alcohol, and devices such as electronic tablets are also considered for their potential to shift circadian timing. Finally, an update on melatonin supplements in the USA is discussed, along with the controversy surrounding the use of melatonin supplements in patients with prediabetes or diabetes.