Why am I so tired on my period?

Exhaustion during your period has three stacked causes, and all are physiology. First, hormones: estrogen and progesterone bottom out at the start of bleeding, and the drop brings real fatigue and low mood. Second, blood loss: a heavy period costs iron month after month, and iron is what carries oxygen - the NHLBI notes iron-deficiency anemia's leading signs are fatigue and weakness, and heavy menstrual bleeding is its most common cause in younger women. Third, sleep: cramps, night sweats, and premenstrual insomnia shave rest right before and during the period. The self-help list: keep exercising lightly even when you do not feel like it - it reliably lifts period fatigue and cramps; eat iron-rich food - red meat, beans, lentils, spinach, with vitamin C to absorb it; protect sleep; and hydrate. Most women feel the lift by day three or four as hormone levels start recovering. The pattern that means get tested: fatigue that is crushing rather than annoying, that persists past your period, or that comes with heavy bleeding - soaking through hourly, large clots - deserves a blood count and ferritin test. Anemia from heavy periods is common, and it is fixable with iron plus treating the bleeding itself. Fatigue out of proportion to your flow also earns a thyroid check. Pymander is a free AI doctor, 24/7 by text. Describe your fatigue and flow, and it can help you decide whether to test.