Perimenopause presents differently in every woman. The timing, sequence, and intensity of symptoms varies widely. Some women sail through with minimal disruption; others find their daily functioning significantly affected. Neither experience is more “normal” than the other.

Below are the most commonly reported symptoms. Note that many overlap with other conditions — thyroid disorders, anaemia, depression, sleep apnoea — which is why professional evaluation is always worth pursuing.

Hot flashes and night sweats

Hot flashes (or hot flushes) are the hallmark symptom of menopause and are experienced by an estimated 75 to 80 per cent of women. They occur due to changes in the hypothalamus — the brain’s thermoregulatory centre — which becomes more sensitive as oestrogen declines, triggering sudden, intense feelings of heat, often accompanied by flushing and perspiration.

Most hot flashes last between one and five minutes. In some women they are occasional and mild; in others they occur dozens of times a day, severely disrupting work, sleep, and quality of life. Night sweats are hot flashes occurring during sleep, and their capacity to fragment sleep over months or years makes them one of the most consequential perimenopausal symptoms.

Fatigue

Fatigue during perimenopause is multifactorial. Disrupted sleep is a major contributor, but declining oestrogen also directly affects mitochondrial function — the cellular machinery that produces energy. Many women describe a particular quality of exhaustion during perimenopause: a heaviness that rest does not fully resolve. Iron levels, thyroid function, and vitamin D status should all be checked in women experiencing significant fatigue, as these are common and treatable contributors.

Brain fog

Described variously as difficulty finding words, poor concentration, slowed thinking, or feeling “not quite sharp,” brain fog is reported by up to 60 per cent of women during perimenopause. While distressing, the research is reassuring: studies consistently show this is a transitional effect, not a marker of long-term cognitive decline. Sleep deprivation alone is capable of producing similar symptoms, and as sleep improves, cognitive function typically follows.

Sleep disturbances

Beyond night sweats, perimenopause can disrupt sleep through changes in circadian rhythm, increased cortisol reactivity, and the decline of progesterone’s sedative effect. Women going through perimenopause report higher rates of insomnia, earlier waking, and reduced total sleep time. Addressing sleep should be a priority, not an afterthought, because its effects cascade through every other system.

Mood changes

Irritability, anxiety, low mood, and increased emotional reactivity are all common during perimenopause. These can feel especially disorienting for women who do not associate themselves with mood instability. Understanding the neurological basis — fluctuating oestrogen affecting serotonin regulation — can itself be grounding. You are not “losing it.” Your brain chemistry is responding to a genuine biological event.