Original scientific paper
Influence of Two Different Light Intensities from 16:00 to 20:30 Hours on Evening Dressing Behavior in the Cold
Hee-Eun Kim
Hiromi Tokura
Abstract
The present experiment tested our hypothesis that the subjects will wear more clothing in the evening cold under the
influence of bright light exposure in the late afternoon and evening. Nine young female adults participated in this study.
Light intensity was controlled from 9:00 h to 16:00 h at 100 lx, and from 16:00 h to 20:30 h either at 3000 lx in the bright
light (»Bright«) or at 10 lx in the dim light (»Dim«) conditions. Light intensity was maintained at 10 lx from 20:30 h to
23:00 h. They were instructed to wear garments to maintain themselves to feel comfortable during the fall of ambient
temperature from 30 °C to 15 °C (21:00 h ~ 22:00 h) and its constant temperature at 15 °C (22:00 h ~ 23:00 h). Most subjects
dressed in heavier clothing in the »Bright« than in the »Dim« conditions. The evening fall of core temperature was
significantly smaller and the urinary melatonin secretion was significantly lower in the »Bright« condition, suggesting
that the set-point of core temperature has been set at a higher level during the evening and at night, being influenced by
the less amount of melatonin secretion. Thus, it is concluded that the late afternoon and evening bright light exposure
could accelerate the dressing behavior in the evening cold.
Keywords
dressing behavior; bright/dim light exposure; melatonin; core temperature; set-point
Hrčak ID:
27301
URI
Publication date:
4.1.2007.
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