Why do I feel anxious and low before my period?

The late-cycle hormone drop shifts brain chemistry, and for many women mood dips, irritability and anxiety arrive on schedule each month. That is PMS, and it is physiology, not weakness.

When the premenstrual week brings severe depression, rage or hopelessness that disrupts life and lifts with bleeding, the name is PMDD, and it responds well to specific treatments.

Track mood against your cycle for two months; the pattern on paper is the diagnosis half-made, and it separates cycle-driven mood from depression that merely worsens premenstrually.