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Circadian Time of Morning Light Administration and Therapeutic Response in Winter Depression
Jiuan Su Terman, PhD;
Michael Terman, PhD;
Ee-Sing Lo, PhD;
Thomas B. Cooper, MA
Arch Gen Psychiatry. 2001;58:69-75.
Background We investigated a possible mechanism of action for the antidepressant
response to light—phase advances of the circadian clock—by measuring
the onset of melatonin secretion before and after light treatment in the morning
or evening.
Methods Plasma melatonin was sampled in 42 patients with seasonal affective
disorder, in the evening or overnight while depressed and after 10 to 14 days
of light therapy (10 000 lux for 30 minutes) when symptoms were reassessed.
Results Morning light produced phase advances of the melatonin rhythm, while
evening light produced delays, the magnitude depending on the interval between
melatonin onset and light exposure, or circadian time (morning, 7.5 to 11
hours; evening, 1.5 to 3 hours). Delays were larger the later the evening
light (r = 0.40), while advances were larger the
earlier the morning light (r = 0.50). Although depression
ratings were similar with light at either time of day, response to morning
light increased with the size of phase advances up to 2.7 hours (r = 0.44) regardless of baseline phase position, while there was no
such correlation for evening light. In an expanded sample (N = 80) with the
sleep midpoint used as a reference anchor for circadian time, early morning
light exposure was superior to late morning and to evening exposure.
Conclusion The antidepressant effect of light is potentiated by early-morning administration
in circadian time, optimally about 8.5 hours after melatonin onset or 2.5
hours after the sleep midpoint.
From the Clinical Chronobiology Program (Drs J. Terman and M. Terman),
and the Department of Analytical Psychopharmacology (Dr Lo and Mr Cooper),
New York State Psychiatric Institute, New York, and the Department of Psychiatry
(Dr M. Terman), Columbia University, New York.
Corresponding author and reprints: Michael Terman, PhD, New York
State Psychiatric Institute, 1051 Riverside Dr, Unit 50, New York, NY 10032
(e-mail: mt12{at}columbia.edu).
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