Purpose
 In a series of our recent studies, systematic mild hyperthermia treatments, such as sauna, hot spring and a special bath for medical treatment, were found to activate leucocytes and to enhance immunity. Although they are known to be effective for health promotion, it is not easy for general people to regularly take these conventional hyperthermia. It would be advantageous for elderly persons, sick people and pregnant women as well as pressed business persons if it is able to minimize stress which might be induced by the conventional hyperthermia, such as high temperature heat, water pressure and humidity. To pursue a further study of the effect of hyperthermia itself, in this research, we utilized nano-mist sauna (NMS), a new hyperthermia treatment. NMS, a new type sauna, is characterized by the ability to produce ultra small fog-shaped hot water called nano-mist, which hardly condenses dew. And we studied the effect of NMS on body temperature, leukocytes, autonomic nerve function and energy production.
Method
 We obtained peripheral blood from six healthy male volunteers (age, 46.5±8.5 years) before and after NMS hyperthermia (20min, 40°C, 100%RH) for lactate and blood glucose measurement and flowcytometric analysis. Body temperature (hypoglossal) and pulse rates were also measured. The statistical analysis difference between the values was determined by paired t-test and Kruskal-Wallis test.
Result
 After NMS hyperthermia body temperature and the level of PO₂ rose (36.8→37.2°C), (52→61mmHg) (p<0.05). On the other hand, the level of lactate showed decrease in all subjects. The ratio and the numbers of NK cells decreased (21.8→17.7%, 498→436/μL) (p<0.05) while those of B cells increased (9.5→12.1%, 261→349/μL) (p<0.05).
Discussion
 Several investigators report that the conventional hyperthermia enhances the primordial immune system (i.e. extrathymic T cells, NK cells, NKT cells and granulocytes) via dominance of sympathetic nerve system function (SNS) . Conversely, in our study, those of the conventional immune system (i.e. T and B cells) was enhanced, suggesting suppression of SNS function. It is reported that the expression level of HLA-DR on the B cells was elevated during hyperthermia (body temperature rose). SNS function (hypothermia) is stimulated by stress and it is suppressed by relaxing (hyperthermia) in the opposite. And it is considered that NMS hyperthermia suppressed SNS and that it was also consistent with our result of lactate decrease. It is possible to consider that NMS hyperthermia may impact on autonomic nerve activating leucocytes. Therefore NMS may be a kind of effective health promotion for valetudinarian (ie an infant, a female) and both a caregiver and a caretaker.