The Transglobal crew will not just carry out experiments but be the guinea pig of a physiology experiment. The purpose of this study, in collaboration with Hôpital de la Tour, Meyrin (Geneva canton), are biological changes in humans exposed to the extreme conditions of the North and South poles. Extreme cold, lack of sunlight (or the 24 hour long daylight, according to the season) and the seasonal variations characteristic of these environments influence the circadian cycle and the production of melatonine, thus perturbing sleep, body temperature and hormone production. In particular, the production of thyroid hormones such as thyroxine and triiodothyronine are crucial for the body temperature regulation. The crew’s response to the isolated conditions of this regions will also be measured. Isolation is proven to have an impact on the muscular system, which can also be affected by prolonged immobility.