Over 85% of perimenopausal women experience fatigue — not the tiredness of a long day, but a bone-deep exhaustion that sleep doesn't fix. The reason it doesn't respond to rest is because it isn't primarily a sleep problem. It is a cellular energy problem. Estrogen has receptors inside your mitochondria — the factories that power every cell in your body. When estrogen drops during perimenopause, those factories become measurably less efficient. Five hormonal systems drain your