Relaxation Oscillations of the Human Body Surface Temperature after External Impacts

The time dependences of the surface temperature of the human body were measured after various external impacts: a cold test, low-intensity optical irradiation, etc. One of the main components contributing to the value of surface temperature is blood microcirculation. The temperature was measured using thermographs in the infrared range. Relaxation oscillations were found on the time dependences. These temperature fluctuations have frequencies significantly lower than those calculated for normal blood flow and, apparently, are caused by other factors. The aim of this work is to determine the possible periods of oscillations arising after exposure. The problem of finding periods is a solution to an incorrect inverse problem. It is performed a Fourier analysis of the obtained time dependences of temperature by the F-approximation method. The calculated periods of possible fluctuations that occur when restoring the palm temperature after a cold test are 4, 7-8, 1011, 14, and 18 minutes. For the case of oscillations that occur when the forearm is irradiated with low-intensity radiation (640 nm) for 6, 10, 15 min, the following periods of temperature fluctuations during relaxation were obtained: 1.5-2, 3-5, 7-9, 11-14, 18-20, 27, 32 minutes. Probably the response times to external influences in the form of changes in surface temperature are about 20 minutes and they are determined by the work of the hypothalamus and associated with regulatory processes involving feedback that start after the system leaves the equilibrium state and try to return it back.