The control of thermoregulatory sweating is primarily under sympathetic nervous system regulation coordinated by the hypothalamus. If central temperature drops below 37 degrees, muscle tremor (shivering) and cutaneous vasoconstriction resulting in cooler periphery, as well as behavioral adaptation (i.e. putting on clothes). If the temperature is above 37 degrees, sweating and cutaneous vasodilation occur. The factors influencing the amount of sweating include emotional state, plasma osmolality, oxygen tension and hormonal state. For example, progesterone tends to lead to higher body temperature and lower rate of sweating, estrogen the opposite. As would perhaps be predicted, a decrease in blood volume or increase in concentration of plasma proteins (i.e., hypovolemia or increased plasma osmolality) lowers the rate of sweating.