Why You're Exhausted But Can't Sleep

If you're collapsing on the sofa at 9pm and then lying awake at midnight wondering why, this is for you.

By Jennifer Swallow, Nutrition Consultant

You're tired all day. Genuinely, bone-deep tired. You think about your bed at 3pm. You fall asleep on the sofa by nine. And then you get into bed and you're wide awake - or you fall asleep fine and wake at 3am with a racing mind, completely alert, unable to get back down. By morning you feel worse than when you went to bed.

This wired-tired pattern is one of the most disorienting things about perimenopause, and one of the most commonly dismissed. Women are told it's stress, told to put their phone away earlier, told to try a lavender pillow spray. None of that touches what's actually happening, which is that oestrogen and progesterone - both of which play significant roles in sleep architecture - have started behaving unpredictably.

What your hormones are doing to your sleep

Progesterone, which tends to decline earlier in perimenopause than oestrogen, is a natural sleep promoter. It works partly through the same GABA pathway involved in anxiety: progesterone's metabolite allopregnanolone activates GABA receptors, producing the calming, sleep-conducive effect that makes it easier to drop off and stay down. As progesterone falls, that natural sedation reduces. You're not less tired, you're just less able to access restful sleep.

Oestrogen has its own role in sleep architecture, particularly in maintaining REM sleep - the restorative phase that's important for memory consolidation, emotional regulation and brain repair. As oestrogen fluctuates in perimenopause, REM sleep is disrupted even on nights when hot flushes or night sweats aren't waking you. This is why many women feel unrested despite spending a reasonable number of hours in bed.

Cortisol follows a natural daily rhythm, peaking in the morning and dropping through the evening to allow sleep. In perimenopause this rhythm can become dysregulated - cortisol stays elevated later into the evening, or spikes at the wrong time. This can produce a second wind around 10 or 11pm: you were exhausted an hour ago, and now you're suddenly alert. Getting into bed before that window closes rather than waiting for the next wave of tiredness is the practical response. That evening second wind is often cortisol-driven, not a recovery.

What actually helps

Magnesium glycinate in the evening is consistently one of the most useful interventions I see in practice for this pattern. It supports GABA signaling, helps regulate the cortisol response, and can promote deeper sleep without the grogginess of pharmaceutical options. The glycinate form matters here - magnesium oxide and citrate are less well absorbed and more likely to cause digestive issues.

What you eat in the evening also has more impact than most people realise. Tryptophan - an amino acid found in poultry, eggs, pumpkin seeds and dairy - is the precursor to serotonin, which in turn converts to melatonin. Eating a small amount of tryptophan-rich protein alongside a complex carbohydrate in the evening (the carbohydrate helps tryptophan cross into the brain) supports the melatonin production needed to feel genuinely sleepy. This isn't about a heavy meal before bed - it's about the composition of what you eat in the two to three hours before sleep.

Blood sugar is also worth examining specifically at night. A blood sugar drop at 2 or 3am can trigger cortisol release, which wakes you up feeling alert rather than sleepy. If you're waking consistently in that window, a small amount of protein and fat before bed - a handful of nuts, a piece of cheese, a boiled egg - can be enough to stabilise blood sugar through the night. It sounds too simple to work. In my experience it often does.

Alcohol deserves an honest mention. It makes you fall asleep faster but consistently disrupts sleep architecture in the second half of the night, particularly REM sleep. For women who are already struggling with sleep quality in perimenopause, even moderate intake tends to make things noticeably worse. This isn't about cutting it out entirely - it's about understanding that the glass of wine that seems to help you unwind is likely costing you the deeper sleep you need.

Sleep is the foundation that everything else builds on. The brain fog, the anxiety, the difficulty with word retrieval - all of these are significantly worse on poor sleep, because sleep is when the brain consolidates, repairs and resets. Addressing sleep isn't just about feeling less tired; it's one of the most direct interventions available for perimenopausal cognitive symptoms.

If you've been managing disturbed sleep for months and feel like you've tried everything, a Brain Fog Clarity Session is a good place to start looking at what's actually driving it - because the answer is usually specific to the individual, and the solution should be too.