The functions of progesterone include using fat for energy, decreasing water retention, eliminating depression and anxiety, I improving mental function, increasing sex drive and increasing the effectiveness of other hormones like thyroid hormone, testosterone and estrogen. A deficiency of progesterone can explain most of the symptoms of menopause. Hot flashes occur when the pituitary gland in the brain is attempting to force the the ovary to make its original amount of estrogen and initiate ovulation. When progesterone is available in the proper amounts the hot flashes decrease because the gland in the brain assumes ovulation is functioning normally since progesterone is around. Mood swings can also be traced to progesterone deficiency or an estrogen excess.
Progesterone has a calming sedative effect on the brain.
It attaches to a receptor in the brain that decreases anxiety and elevates mood. This receptor in the brain is called the GABA receptor. The GABA receptor is the same receptor Prozac and other antidepressant and anti-anxiety drugs use to produce their effect on the brain. Insomnia is another frequent complaint of women during menopause. The insomnia is probably due to the lack of the calming effects of progesterone.