Hormonal fluctuations are common in all species, including humans, and are especially common as we get older. This can cause a lot of distress for some people, and it's almost inevitable that women will have to deal with it at some point in their lives, particularly as menopausal symptoms begin to manifest. Various hormones produced by nature serve various functions in different people. Hormones, including progesterone, testosterone, and estrogen, among others, are impossible to ignore because of their influence on a wide range of human.