Frequently occurred sudden deaths in the bath have become to serious problem in Japan. Sudden death in the bath possibly concerned with neurally mediated syncope. During and after bathing, bather is possibly tended to occur orthostatic intolerance by thermal stress to the circulatory dynamics. The experiment was performed focused on changes in cerebral and cardiovascular hemodynamics by postural change in the bathing to discuss the safe way of bathing.
On 9 healthy young subjects, 41±1°C bathing was performed 15 minutes, change in oxidized hemoglobin (ΔOxyHb) on the forehead as an indicator of cerebral blood flow was monitored by near-infrared spectroscopy method at interval of 0.5s through the experiment. In sitting and upright position, blood pressure and heart rate were measured before bathing, at 5 minutes, 10 minutes and 15 minutes (upright with head down) after immersion and after bathing.
Some subjects felt dizziness at upright during and/or after bathing. It suggests that orthostatic stress under heat stress is implicative even for healthy young. ΔOxyHb for subjects with dizziness at upright during bathing is significant lower below the baseline than it for subject without dizziness.
Degrees of depression of systolic blood pressure, elevation of heart rate and depression of cerebral blood flow by standing at 10 minutes after starting immersion were significant larger than their values before bathing. Degree of elevation of heart rate and depression of cerebral blood flow by standing with head down were significant smaller than their value at standing without head down. It suggests that upright with head down reduce the orthostatic stress to the cerebral and cardiovascular hemodynamics.

The comfortability and safety on resort were investigated in terms of resort environments focusing on atmosphere temperature.
With regard to the comfortability, first, a discomfort index (DI) defined with atmosphere temperature and relative humidity was demonstrated to be associated with indicators of autonomic nerve activities derived from heart beat variability at the level around DI-70 which was classified into the category of “comfortable for most of people”.
Secondarily, it was suggested that the index could be available to evaluate comfortability for given time courses at different resort points with an example of its hourly average in 24 hours a day for a representative month in each season. With regard to the safety, first, stroke incident rate of each month was associated with monthly average atmosphere temperature when the relationship was analyzed using around ten thousands patients data for 7 years from the community-based stroke registration for in Toyama prefecture. On top of that, it has been demonstrated that the atmosphere temperature on one and two days prior to the stroke development was independently effective on the risk of cerebral hemorrhage and subarachnoidal hemorrhage development with the adjustment for patient's sex and age, calendar year, season, relative humidity and atmosphere pressure. Secondarily, morning raise in blood pressure was affected by the room temperature (10°C and 25°C). The lower temperature the more raise in blood pressure.

Spa could have direct effects for physical and mental health but also non-daily pleasure with a visit to spa itself and surroundings. Therefore, the visit should be strongly related with quality of life (QOL) as well as general health status. First of all, this study was conducted to clarify these relationships. Secondly, the QOL was investigated as a confounding factor to health effects of spa. Subjects of this study are about all 6, 000 citizens older than 40 years of age living in Japanese J-town. Self-administrated questionnaires were distributed to the subjects at once and collected for the analysis (Response rate; 94.5%). With regard to the spa visit, (1) no visit at all recently in two or three years, (2) once a year, (3) twice or three times a year and (4) once a month, (5) twice or three times a month were classified.
With regard to QOL (Quality of Life), a questionnaire of WHO-QOL was used. The present study demonstrated the visitors to spa have significantly higher WHO-QOL for each subcategory; physical health, psychological status, social relationship, and environment status compared with non-visitors. Therefore, the visitors have had higher total scores of WHO-QOL compared with non-visters. With regard to past history of fracture, the visitors have had significantly lower it's prevalence compared with non-visitors. However, the significance of prevalence was cancelled in adjusting the WHO-QOL. WHO-QOL relating to the frequency of spa visit as well as the prevalence of fracture was identified as a confounding factor to health effects of spa.