When it comes to the body, estrogen, insulin, cortisol, thyroid, and other hormones help keep it running smoothly. As women age and their bodies change, estrogen starts declining in a manner that is very erratic. As a result, some women experience hot flashes, hair loss, sleeplessness, irritability, gastrointestinal discomfort, loss of libido, and skin changes. Their skin may become dry, flaky, thinner, and more delicate.