Perimenopause, explained: the science of the transition and how to thrive through it

A brain in motion

In 2021, a team at Weill Cornell Medicine in New York scanned the brains of more than 160 women aged 40 to 65. Some had not yet started perimenopause, some were in it, and some had completed the transition.

The scans showed a brain in motion. During perimenopause, its structure, connections and energy use all shifted. After menopause, they settled into a new balance, and grey matter recovered in key areas for memory and thinking. The brain also produced more energy at the cellular level, and memory and thinking held steady.

The researchers described menopause as a dynamic neurological transition. In their words, the brain finds a new normal. Perimenopause is a period of change that the brain and body are well equipped to meet.

A transition in midlife

Perimenopause is the stage leading up to menopause. It often begins in the early to mid forties, and the average age of menopause in the UK is 51.

Every woman’s experience is her own. Some notice very little change. Others notice shifts in temperature, sleep, mood or memory, and the pattern can vary from month to month. Understanding what is happening makes each of these changes easier to recognise and support.

These years often meet the height of a career. In the UK alone, more than six million women aged 40 to 60 are in work.

What happens in the body

Perimenopause begins in the ovaries. As the supply of eggs gets lower, oestrogen moves away from its steady monthly rhythm. Levels rise and fall less predictably, sometimes higher than before and sometimes lower.

Oestrogen acts far beyond the reproductive system, so these shifts reach the whole body. The brain has oestrogen receptors in the areas that guide temperature, sleep, mood and memory. Bones and muscles respond to oestrogen too.

Temperature is often the first to show the change. The hypothalamus, which works like the brain’s thermostat, becomes more sensitive and releases warmth through the skin more readily. Doctors call hot flushes and night sweats vasomotor symptoms. At night they can make sleep lighter, and sleep shapes energy, focus and mood the next day.

These links are good news. Because the systems are connected, a few foundations support all of them at once.

Memory and focus

Many women notice that memory works a little differently during perimenopause. A word may take longer to find, or a name longer to recall. About six in ten women notice changes like these.

Research shows that the brain adapts. A large American study followed more than 2,000 women through the menopause transition and tested their memory and thinking speed each year. During perimenopause, learning new information took a little more effort. After menopause, scores returned to their earlier levels.

The change is temporary. Experience and expertise stay where they were.

Foundations for thriving

Wellbeing through perimenopause starts with knowing one’s own patterns. A simple four-week diary of sleep, energy, mood and cycle shows how the body is changing. In women over 45, doctors usually confirm perimenopause from this kind of picture alone, without a blood test.

Sleep is the next foundation, since it supports almost everything else. A regular bedtime and wake time keep the body’s rhythm steady. A cool, dark bedroom and light bedding help the body hold a comfortable temperature at night. Less alcohol and caffeine later in the day support deeper sleep and fewer hot flushes.

Movement builds on good sleep. As oestrogen changes, bones and muscles benefit from extra support, so strength training and weight-bearing exercise, such as brisk walking, become especially valuable. Regular exercise also lifts mood and deepens sleep. A balanced diet with enough calcium and vitamin D supports bone health too.

Medical care completes the picture. A doctor who has time to listen can talk through every option. Hormone replacement therapy (HRT) is the main treatment for hot flushes and night sweats, and for many women it also supports sleep and mood. Cognitive behavioural therapy (CBT), a structured talking therapy, is also recommended in a form designed for menopause, alongside HRT or on its own. Each woman can choose what fits her health and preferences.

Together, these foundations do more than support a transition. They build health for the decades that follow.

Workplaces where everyone thrives

The workplaces that support perimenopause best are simply good places to work. Flexible start times, the option to work from home, good ventilation, cold water and comfortable uniforms help everyone feel and work at their best.

Culture matters as much as the office itself. Women say they feel most supported by their colleagues. When health is an ordinary topic at work, asking for a later start or a desk by the window feels natural. A clear policy that everyone can find makes those conversations simple.

In the UK, this support is also set out in guidance. In 2024, the Equality and Human Rights Commission published guidance on how employers can support people through menopause. Most of it is the same everyday care described here.

A new normal

Perimenopause is a transition the brain and body are built to make. The science shows change, then adaptation, then a new balance.

With knowledge, good habits and the right support, women move through these years feeling well and doing their best work.

On Sunday, for World Menopause Day, we will share six common myths and what the evidence says.

Sources

Mosconi L and colleagues. Menopause impacts human brain structure, connectivity, energy metabolism, and amyloid-beta deposition. Scientific Reports, 2021.

Greendale GA and colleagues. Effects of the menopause transition and hormone use on cognitive performance in midlife women. Neurology, 2009.

NICE. Menopause: identification and management (NG23), updated 2024.

CIPD. Menopause in the workplace: Employee experiences in 2023.

Equality and Human Rights Commission. Menopause in the workplace: Guidance for employers, 2024.

NHS. Menopause.

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