X-Message-Number: 24440
Date: Tue, 27 Jul 2004 05:26:40 -0700 (PDT)
From: Doug Skrecky <>
Subject: could bright light exert an antiaging effect?

J Clin Endocrinol Metab. 2001 Jan;86(1):129-34.
Diminished melatonin secretion in the elderly caused by insufficient
environmental illumination.
  The pineal hormone melatonin has some circadian regulatory effects and
is assumed to have a close relation with sleep initiation and maintenance.
Many previous reports have described age-related decreases in melatonin
levels, especially in elderly insomniacs (EIs), which may act as causal or
exacerbating factors in sleep disturbances in the elderly. Ten elderly
residents with psychophysiological insomnia (mean age, 74.2 yr), 10
healthy residents of the same home [elderly control (EC) group; mean age,
72.7 yr], and 10 healthy young control subjects (mean age, 20.9 yr)
living at home participated in this study. The elderly persons, especially
the EIs, were exposed to significantly less environmental light and
simultaneously suffered from significantly diminished nocturnal melatonin
secretion. Supplementary exposure to 4 h (1000 to 1200 h, 1400 to 1600 h)
of midday bright light in the EI group significantly increased melatonin
secretion to levels similar to those in the young control group without
circadian phase-shifting. There was a tendency for the magnitude of the
increase in nocturnal melatonin secretion stimulated by bright light to
parallel amelioration of sleep disturbances in these subjects. The present
findings suggest that we need to pay attention to elderly individuals who
suffer under conditions of poor environmental light resulting in
disorganized circadian rhythms, including the sleep-wake cycle.

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