What age does perimenopause usually start?

Most often in the mid-40s, but it can begin in the late 30s. It typically lasts around four years, though it varies widely from woman to woman.

What is usually the first sign of perimenopause?

For many women it’s a change in their cycle (periods becoming shorter, longer or less predictable) often alongside lighter sleep or mood changes. There’s no single universal first sign.

Can I be in perimenopause and still have regular periods?

Yes. Early on, cycles can stay fairly regular while other signs (sleep, mood, brain fog) appear first. Tracking several signals together gives a clearer picture than periods alone.

Perimenopause

What are the early signs of perimenopause?

Quick answer

Perimenopause often starts quietly, years before periods stop, commonly in the mid-40s, but sometimes late 30s. The earliest signs are frequently subtle and easy to put down to stress or a busy life: shifts in your cycle, more broken sleep, mood or anxiety changes, and a foggier memory. Because estrogen and progesterone start fluctuating rather than simply falling, symptoms can come and go. That inconsistency is exactly why the pattern is clearer when you track it over months rather than judging a single week.

What might be happening

In early perimenopause, estrogen and progesterone stop following their steady monthly rhythm and begin to fluctuate. That variability (rather than a clean decline) is what drives many of the early signs, and it is why one month can feel very different from the next.

Cycle changes are often the first clue: periods becoming shorter, longer, heavier, lighter or less predictable. Alongside that, many women notice sleep getting lighter, mood or anxiety shifting, and concentration or memory feeling less reliable. Hot flushes and night sweats can appear early too, but plenty of women have none at this stage.

What to notice

Changes in your cycle: length, flow, or how predictable it is
Sleep: falling asleep, staying asleep, early waking, night sweats
Mood and anxiety, and whether they track with your cycle
Focus, memory and brain fog
Energy, and any new hair or skin changes

No single sign confirms perimenopause, and there's no everyday blood test that reliably diagnoses it in your 40s. The pattern across several signals, tracked over a few months, is the most useful thing you can bring to a doctor.

Related patterns

Women noticing early perimenopause often also track disrupted sleep, mood shifts, brain fog, hair shedding, and cycles that are changing in length or flow.

When to get support

See a doctor if symptoms are disrupting your sleep, mood, work or relationships, or if your periods change markedly: very heavy bleeding, bleeding between periods or after sex should always be checked. If you're under 45 with these changes, it's worth a conversation sooner rather than later.