Melatonin, a naturally occurring biological hormone with circadian rhythmicity, has been shown to promote sleep and entrainment to external cues when administered in drug form (0.5–5.0 mg). Melatonin administered in the evening causes phase advances in sleep-wake times while maintaining duration and quality of sleep. Similarly, when administered in the early morning, melatonin can cause phase delays. It has been shown most effective in cases of shift work sleep disorder and delayed phase sleep disorder, but has not been proven particularly useful in cases of jet lag. Dark therapy, for example, the use of blue-blocking goggles, is used to block blue and blue-green wavelength light from reaching the eye during evening hours so as not to hinder melatonin production. See also
References
External links

Circadian Sleep Disorders Network
An American Academy of Sleep Medicine Review: Circadian Rhythm Sleep Disorders: Part I, Basic Principles, Shift Work and Jet Lag Disorders. PDF, 24 pages. November 2007. An American Academy of Sleep Medicine Review: Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep–Wake Rhythm. PDF, 18 pages. November 2007. An American Academy of Sleep Medicine Report: Practice Parameters for the Clinical Evaluation and Treatment of Circadian Rhythm Sleep Disorders, November 1, 2007
NASA Sleep–Wake Actigraphy and Light Exposure During Spaceflight-Long Experiment
Treatment
MEWDS is a self limited disease with excellent visual recovery within 2-10 weeks. However residual symptoms including photopsia may persist for months. == References ==