Using dim light melatonin onset (DLMO) to track body clock timing in sleep and daily rhythm disorders

The dim light melatonin onset (DLMO) is the most accurate marker for assessing the circadian pacemaker.

• DLMO can determine whether an individual is synchronized to a 24-hour light/dark cycle or in a free-running state.
• It is useful for evaluating phase delays or advances of circadian rhythms in individuals who are entrained.
• DLMO has clinical applications for diagnosing sleep and mood disorders, particularly in phase typing patients.
• Recent studies suggest DLMO may help assess chronobiological features of seasonal affective disorder (SAD).
• The DLMO marker can identify optimal timing for therapies like bright light or exogenous melatonin treatments.

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