Mood swings, disrupted sleep, and irregular periods can signal either PMS or the start of perimenopause — and the distinction matters. Here's how to read your hormonal signals by pattern, not just symptom.
PMS and PMDD share timing but differ sharply in severity and clinical definition. This explainer breaks down DSM-5 criteria, the luteal-phase serotonin connection, and a two-cycle tracking method to help you know when to seek care.