What Is Perimenopause?

Perimenopause is the years-long transition leading up to menopause, driven by the gradual, often unpredictable decline in estrogen production as the ovaries prepare to stop releasing eggs. For most women, it begins sometime in their mid-to-late 40s, though it can start as early as the mid-30s — and it can last anywhere from a couple of years to nearly a decade.

What makes perimenopause distinct, and often confusing, is that hormone levels don't decline in a straight line. Estrogen can spike and dip unpredictably from cycle to cycle, which is why symptoms often feel inconsistent — a month of heavy, close-together periods followed by a month with none at all; a stretch of good sleep followed by weeks of disrupted nights.

Common experiences during this phase include irregular periods, hot flashes and night sweats, sleep disruption, mood changes, and shifts in weight and energy. Not every woman experiences every symptom, and severity varies enormously — some move through perimenopause with mild, manageable changes, while others find it significantly disruptive to daily life.

Perimenopause officially ends, and menopause begins, once a woman has gone 12 consecutive months without a period. Everything before that point — however long it lasts — is perimenopause.

Understanding this distinction matters because it reframes what's "normal." Irregular cycles, disrupted sleep, or mood shifts in your 40s aren't necessarily separate problems to solve individually — they may be connected expressions of the same underlying transition, which means addressing the transition itself is often more useful than treating each symptom on its own.

If you're noticing these changes and want a clearer picture of where you stand, the LunaBridge assessment looks at hormonal, metabolic, and lifestyle patterns together.