Original scientific paper
Combined Influences of Gradual Changes in Room Temperature and Light around Dusk and Dawn on Circadian Rhythms of Core Temperature, Urinary 6-Hydroxymelatonin Sulfate and Waking Sensation Just after Rising
Masayuki Kondo
Hiromi Tokura
Tomoko Wakamura
Ki-Ja Hyun
Satoshi Tamotsu
Takeshi Morita
Tadashi Oishi
Abstract
The present experiment aimed at knowing how a gradual changes of room temperature (Ta) and light in the evening
and early morning could influence circadian rhythms of core temperature (Tcore), skin temperatures, urinary 6-hydroxymelatonin
sulfate and waking sensation just after rising in humans. Two kinds of room environment were provided
for each participant: 1) Constant room temperature (Ta) of 27 °C over the 24 h and LD-rectangular light change with
abrupt decreasing from 3,000 lx to100 lx at 1800,abrupt increasing from 0 lx to 3,000 lx at 0700. 2) Cyclic changes of Ta
and with gradual decrease from 3,000 lx to 100 lx onset at 1700 (twilight period about 2 h), with gradual increasing from
0 lx to 3,000 lx onset at 0500 (about 2 h). Main results are summarized as follows: 1) Circadian rhythms of nadir in the
core temperature (Tcore) significantly advanced earlier under the influence of gradual changes of Ta and light than no
gradual changes of Ta and light. 2) Nocturnal fall of Tcore and morning rise of Tcore were greater and quicker, respectively,
under the influence of gradual changes of Ta and light than no gradual changes of Ta and light. 3) Urinary 6-hydroxymelatonin
sulfate during nocturnal sleep was significantly greater under the influence of gradual changes of Ta and
light. 4) Waking sensation just after rising was significantly better under the influence of gradual changes of Ta and
light. We discussed these findings in terms of circadian and thermoregulatory physiology.
Keywords
circadian rhythms; core temperature; skin temperatures; urinary 6-hydroxymelatonin; waking sensation
Hrčak ID:
27388
URI
Publication date:
10.4.2007.
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