05.25.18

White Light Exposure Suppresses Melatonin Secretion in Many Blind People

Source: Medscape

Ocular exposure to white light suppresses melatonin secretion in nearly a third of totally blind individuals, researchers report, according to Medscape.

Ocular exposure to light inhibits pineal melatonin secretion in humans by way of the suprachiasmatic nuclei (SCN), which receive photic input from the retina via the retinohypothalamic tract (RHT). Most blind individuals lack functional integrity of this pathway and, as a result, cannot maintain circadian entrainment to the 24-hour light-dark cycle and exhibit non-24-hour sleep-wake rhythm disorder.

Dr. Steven W. Lockley from Brigham and Women’s Hospital and Harvard Medical School in Boston and colleagues investigated the prevalence of a positive melatonin-suppression response to ocular light exposure in 18 healthy blind persons, 13 of whom had confirmed non-24-hour rhythms and five of whom had confirmed 24-hour rhythms in urinary 6-sulphatoxymelatonin (aMT6s).

Read the full article.

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