Perimenopause is the transitional stage before menopause, often starting in the mid-40s but sometimes earlier. It is marked by hormonal fluctuations, especially declining estrogen, leading to symptoms like irregular periods, hot flashes, mood swings, sleep disturbances, and changes in metabolism. This phase can last several years and is often misunderstood or overlooked, leaving many individuals unprepared for the physical and emotional changes it brings.