M.Yamashita,T.Wakamura(Presenter),S.Nagashima,R.Ohmomo,M.Saito
School of Health Science,Faculty of Medicine,Kyoto University,JAPAN
K.Muramatsu
KYOUSEI Science Center for Life and Nature, Nara Women’s University,JAPAN
M.Yoneda
Faculty of Human Life and Environment, Nara Women’s University, JAPAN
S.Ogawa,M.Okada
R & D Laboratories, Septem Soken Co. Ltd., JAPAN
T.Oishi
Department of Life Vista, Narasaho College, JAPAN

[Abstract]
Many researchers have studied very well on the influences of severe ultraviolet (UV) irradiation to the health condition in skin and eyes using artificial light resource. It is necessary for many people to pay attention to a lot of studies for UV protection. This study aims to make it clear how the exposure to natural solar radiation including UV can influence immunological parameters and heart rate variability in humans. Twenty healthy Japanese male students (mean: 22.2 years old) showing skin type 2 participated in this study. They were randomly divided into two groups which consisted of exposure group (EXP) and protected one (PRO). The back of PRO participants was covered with cotton clothing during sun exposure. They stayed outside for 3 hours between 11:30 to 14:30. Cortisol level tended to decrease after the exposure only in PRO group (0.05<p<0.1). IL-6 level was maintained in PRO group, whereas that tended to increase in EXP group (0.05<p<0.1). Participants in EXP group felt fatigue after solar exposure significantly with higher frequency compared with PRO one (p<0.05). Change of skin color (⊿E) in PRO group was significantly lower than EXP one (p<0.01). The parasympathetic function in EXP group tended to be lower than that of RRO one (0.05<p<0.1). The solar exposure even for the short time of 3 hours may influence the physiological perspective in human. The clothing or sunscreen on the back seems to be effective for protecting human health from the attack of UV included in severe solar radiation.