Exposure to long summer days affects the human melatonin and cortisol rhythms.
Exposure of 8 human subjects in summer to a natural 16 h bright light photoperiod phase advanced the morning salivary melatonin decline and cortisol rise and shortened the nocturnal melatonin signal by 2 h relative to the winter patterns of the same subjects followed under a combined artificial and natural light 16 h photoperiod. The data suggest that summer days experienced from sunrise till sunset and not winter days with a combined artificial and natural light long photoperiod evoke a true long day response of the human circadian system.
Vondrasová
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Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
Hájek
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Illnerová
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D000293:Adolescent; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008029:Lighting; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D017440:Photoperiod; D012463:Saliva / Q000378:metabolism / Q000528:radiation effects; D012621:Seasons; D013472:Sunlight
D008550:Melatonin; D006854:Hydrocortisone