Perimenopause is a transitional stage leading up to menopause. Menopause usually occurs between 45 and 55, and can be retrospectively dated back to a woman's last menstrual period. Perimenopause is the time of change leading up to menopause, and lasts on average about five years. Perimenopause is caused by a gradual decrease in the production of estrogen, and its main indicator is a change in menstruation. Generally, women's cycles become more irregular than normal, and bleeding may become heavier with shorter intervals between cycles. It's best to see your doctor when you experience abnormal bleeding, as this can be a symptom of any number of things, and not just a sign of perimenopause.
Women, thought to be irrational or strongly affected by hormonal changes, are often said to have mood swings during this time, but women's emotional shifts are no more pronounced during perimenopause than during their regular menstrual cycles, just more erratic. However, hormonal shifts during perimenopause can cause sleep disturbance, which would make anyone tired and crabby. Some doctors prescribe a low-dose birth control pill to combat perimenopause, but natural alternatives are available. Speak to a naturopath, or do some reading, if you're interested in herbal remedies to ease your way through perimenopause and menopause.