What You Notice
Sleep, which for most of your life you probably took for granted, becomes one of the first things to turn unreliable. For some women the trouble is at the start of the night, lying there with a mind that will not switch off long after the light is out. For many more the problem comes in the small hours. You fall asleep without much difficulty, and then you snap wide awake at two, three or four in the morning, often at almost the same time night after night, and you lie there as your thoughts begin to churn and sleep refuses to return.
Sometimes you wake suddenly hot, throwing off the covers, your chest and neck damp with a night sweat, only to feel chilled a few minutes later. Sometimes there is no obvious reason at all, you are simply awake. The hours between three and five can feel especially lonely, with worries looming far larger than they would in daylight. Whatever the pattern, the result is the same. Your night is broken into fragments rather than one deep, continuous rest, so even after seven or eight hours in bed you wake feeling as though you barely slept, groggy and unrefreshed, and that debt then rolls into your mood, your energy and your focus the next day.
Why It Happens
There are a few reasons this stage hits sleep so hard. The first is progesterone, your naturally calming, sleep-promoting hormone. Because it is usually the first to decline in perimenopause, disturbed sleep is often one of the earliest signals that your hormones are changing at all. As progesterone falls, your nervous system finds it harder to power down, so both dropping off and staying asleep become more difficult.
The second is estrogen, which as it falls and fluctuates causes two separate problems. It destabilises your body's internal thermostat, triggering the night sweats and hot flushes that physically wake you and leave you too hot and restless to settle again. It also unsettles your mood and raises anxiety, and an anxious, alert brain at three in the morning is far more likely to start racing than to drift back into sleep. There is also a quieter and more serious cause that deserves attention. The risk of obstructive sleep apnoea, a condition where the airway repeatedly narrows or closes during sleep and briefly stops your breathing, rises noticeably after menopause, and it is frequently missed in women because it is wrongly thought of as something that only affects men. If you snore loudly, gasp or choke in your sleep, or wake feeling utterly unrefreshed no matter how long you were in bed, that is well worth raising with a doctor rather than putting down to hormones alone, because it is very treatable once found.
Educational only, not medical advice. Further reading: NICE guideline NG23, The Menopause Society, American Academy of Sleep Medicine (aasm.org), research on menopause and sleep apnoea.