Disclosed is a biological state estimation device that can apprehend not only the activity of the autonomic nervous system, but also the brain function activation state. The biological state estimation device is configured so that, using biological signals sampled from the upper body of a human, the level of homeostatic function is segmented into a plurality of gradations and the level of homeostatic function is determined, and in accordance with a time axis wherein each gradation level of homeostatic function is indicated on a horizontal axis, a time series is plotted which is displayed as a graph on a display means. Preferably, the uppermost section of the vertical axis of the graph is a hyperactive state, and the lowermost section is a state of a decline in function. As a result, it is possible to apprehend as a periodic function: the condition of fluctuations due to the autonomic nervous system as the maintenance of homeostasis is attempted; the condition of fatigue progressing; and the condition of the addition of stimulation due to brain activation. Also, it is possible to apprehend phenomena heralding the onset of sleep.
BIOLOGICAL STATE ESTIMATION DEVICE, BIOLOGICAL STATE ESTIMATION SYSTEM, AND COMPUTER PROGRAM