The cause of hot flashes is not completely understood. It is believed that the hypothalamus, a part of the brain involved in temperature regulation undergoes changes that lead to hot flashes. During perimenopause and menopause, the hypothalamus becomes more sensitive to minor elevations in body temperature and signals mechanisms to dissipate body heat. These mechanisms include dilation of blood vessels in the skin causing heat and flushing, sweating, and palpitations.
Declining estrogen levels play a role in this process, which is why symptoms occur around menopause and why estrogen is an effective therapy. In addition, certain brain chemicals, called neurotransmitters, also play a role. In particular serotonin, norepinephrine, and endorphins are thought to be involved in the generation of hot flashes. Nonhormonal treatment modalities are thought to help by modulating these systems of neurotransmitters.