Your Watch May Notice Perimenopause Before Your Calendar Does

For a lot of women, the first sign that something is shifting isn't a missed period. It's the 3am wake-up that wasn't there a year ago — the one you blame on stress, or wine, or the dog. New data from a large wearable study suggests those broken nights may be an early fingerprint of the menopause transition, showing up before the calendar catches on.

What the study looked at

Researchers at the Harvard T.H. Chan School of Public Health, working with the Apple Women's Health Study, analyzed 94,118 nights of Apple Watch sleep data from 338 women. Most were aged 45 to 59, and the data spanned the year before and the year after each woman's final logged menstrual period. Because a watch measures sleep every night, it can catch gradual shifts that a one-off question at a checkup would miss.

The pattern: more time awake, earlier

The standout finding was about wake after sleep onset, or WASO — a slightly clinical term for a simple thing: the minutes you spend awake after you've already fallen asleep. Middle-of-the-night wakefulness, essentially.

In the 18 months leading up to menopause, 60% of the women showed an increase in WASO compared with the previous six months. The average rise was about 7%. In plain terms: a majority of women were waking up more during the night in the year and a half before their periods stopped for good.

Just as telling, this was more than ordinary aging. Across the transition, women spent about 0.8% more of their sleep time awake — roughly four extra minutes awake in an eight-hour night. For women who simply got two years older without going through menopause, the increase was about 0.2%, or one extra minute. So the transition adds a sharper bump in broken sleep than aging alone would predict.

The disruption didn't happen in isolation. Among women tracking their sleep, the most common symptoms were hot flashes, irritability, mental exhaustion and sexual symptoms — and those reporting more severe bladder, joint, heart-discomfort or depressive symptoms tended to have the most disrupted, and least, sleep.

The honest caveats

This is the part worth reading twice. Sixty percent is a majority, not everyone — many women in the study showed no meaningful change in their sleep at all. As the researchers put it, "each person experiences perimenopause and menopause differently." The study is observational, which means it can spot patterns but not prove cause and effect, and menopausal status was partly self-reported.

Most importantly: a watch cannot diagnose perimenopause. Rising nighttime wakefulness has many possible causes — stress, a snoring partner, alcohol, sleep apnea, a new medication. What the data supports is narrower and more useful: broken sleep can be an early, trackable signal that something is changing, and it's worth paying attention to rather than dismissing.

How to use this

You don't need to panic-read your sleep score. The practical move is to notice trends, not single nights. If your nights have been getting more fragmented over months, with no obvious new cause, that's a pattern worth logging — and worth raising with a clinician, especially alongside other changes like cycle shifts, hot flashes or mood. Monitoring your sleep the way you might track your cycle turns a vague "I feel off" into something concrete you can talk about.

Where Joise fits

A watch can record the nights. The harder part is connecting a slow drift in your sleep to how you actually feel and function — and knowing when it's worth acting on. That's what we're building Joise to do: turn signals like rising nighttime wakefulness into something you can track over time and bring to a real conversation.

This article is educational and is not individual medical advice. Talk to a qualified healthcare professional about your own health.

References

A Transition of Seasons: Sleep Patterns and Changes in Perimenopause. Apple Women's Health Study, Harvard T.H. Chan School of Public Health, May 2026. Read the study update.

Kravitz HM, Joffe H. Sleep During the Perimenopause: A SWAN Story. Obstetrics and Gynecology Clinics of North America, 2011 (background).