In the years leading up to menopause, the body begins to produce less estrogen. This can lead to a range of symptoms experienced in perimenopause such as hot flashes, night sweats, lower sex drive, vaginal dryness, osteoporosis, insomnia, mood swings or depression, and impairments to memory and concentration. This is the most common time to experience low estrogen, but it can also affect young women for specific reasons such as an autoimmune condition or eating disorder.