Seasonal light changes are known to alter melatonin activity. In PIT,
information about the light received from the retina reaches the
suprachiasmatic nucleus via the retinohypothalamic pathway, and from
there to the pineal gland, and melatonin secretion is regulated. PIT has
been shown to be effective in non-seasonal depression (Kripke et al. 1992,
Yamada et al. 1995). It has been stated that the effect of bright light
therapy is based on the initiation of melatonin circadian rhythm at night
when light is given in the morning (Terman et al. 2001). There are 3 main
studies conducted using PIT in pregnant women. Wirz-Justice et al. applied
bright PIT or sham for 5 weeks in pregnant women diagnosed with
non-seasonal depression in their randomized double-blind study. The rate
of response to treatment was statistically significantly higher in the PIT
group (81.3%) than in the sham group (45.5%). Likewise, remission rates
were found to be statistically significantly higher in the PIT group. PIT has
been defined as a non-pharmacological and non-invasive treatment that is
effective, simple, and safe for mother and baby.
There are many clinical scientific studies showing that it is effective in
sleep disorders and M. Depression.