Light affects morning salivary cortisol in humans

The effect of light on the morning-cortisol peak in humans was investigated in fourteen healthy men by exposing them to darkness and to light of 800 lux during a 1-h period on two subsequent mornings. In the early morning, we demonstrated a temporary increase of salivary cortisol levels after awaken...

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Bibliographic Details
Published in:The journal of clinical endocrinology and metabolism 1999-09, Vol.84 (9), p.3395-3398
Main Authors: SCHEER, F. A. J. L, BUIJS, R. M
Format: Article
Language:English
Subjects:
Adrenals. Interrenals
Adrenocortical hormones. Regulation
Adult
Biological and medical sciences
Circadian Rhythm
Fundamental and applied biological sciences. Psychology
Humans
Hydrocortisone - metabolism
Light
Male
Saliva - metabolism
Vertebrates: endocrinology
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Summary:The effect of light on the morning-cortisol peak in humans was investigated in fourteen healthy men by exposing them to darkness and to light of 800 lux during a 1-h period on two subsequent mornings. In the early morning, we demonstrated a temporary increase of salivary cortisol levels after awakening, while light exposure resulted in a +/- 35% further increase in cortisol levels. Cortisol levels 20 and 40 min after waking were significantly higher during 800 lux exposure than during darkness. In order to investigate the time-dependency, the experiment was repeated in the late evening. In the evening, light had no effect on cortisol levels. These results demonstrate that light conditions in the early morning have a strong impact on the morning-cortisol peak, but that evening cortisol levels are unaffected by light. The possible role of the circadian pacemaker as mediator of the light effect on cortisol level is discussed.
ISSN:0021-972X
1945-7197
DOI:10.1210/jc.84.9.3395