Live Recordings (Sleep Medicine Trends 2026)-06 Working Against the Clock- Clinical Care for Circadian Rhythm Disruption

Video Transcription

Video Summary

Circadian rhythms are ~24-hour biological cycles that organize behavior and physiology, coordinated in mammals by the suprachiasmatic nucleus (SCN) in the hypothalamus. Circadian phase can be measured with markers like dim-light melatonin onset (DLMO) and the core body temperature minimum, which corresponds to the worst time to be awake and make decisions. Most people’s intrinsic “tau” is slightly longer than 24 hours, making phase delays (e.g., adjusting to westward travel) easier than phase advances.<br /><br />Light is the strongest “zeitgeber”: evening light delays the clock, while morning light advances it. Melatonin has an opposite phase-response curve; taken in the late afternoon/early evening (before one’s own melatonin rises) it can advance circadian timing—highlighting why many patients say melatonin “doesn’t work” when mistimed.<br /><br />The talk reviews circadian rhythm sleep-wake disorders: delayed and advanced sleep-wake phase disorders, irregular sleep-wake rhythm (common in neurodevelopmental/degenerative conditions), and non-24-hour disorder (often in total blindness; treated with timed melatonin or tasimelteon). Shift work and jet lag are discussed, emphasizing practical education, workplace scheduling, and strategic light/dark management. The speaker argues for better biomarkers (wearables, melatonin testing) and more research to personalize treatment.

Keywords

circadian rhythms

suprachiasmatic nucleus (SCN)

dim-light melatonin onset (DLMO)

core body temperature minimum

zeitgeber light exposure

melatonin phase-response curve

circadian rhythm sleep-wake disorders

non-24-hour sleep-wake disorder