The part that doesn’t get explained well enough is that perimenopause mood instability usually isn’t about oestrogen being low. It’s about oestrogen being erratic. That distinction matters more than most people realise. I work in a compounding pharmacy where we handle a lot of hormone preparations. What I can tell you from the technical side: the brain’s serotonin system is genuinely sensitive to oestrogen fluctuations, not just levels but the rate of change. A slow decline is one thing. Rapid swings up and down, which is what early perimenopause typically looks like, hit the nervous system differently. It’s not you going “crazy.” It’s a system that was calibrated to stable hormone levels suddenly getting unpredictable inputs. A few things that come up a lot when people raise this: Why does it feel worse some days than others? Because oestrogen can swing significantly within a single cycle, even within a few days. If you’re tracking your mood and it feels random, it might correlate more closely with cycle phase than you’d expect, even in an irregular one. Does timing of any treatment matter? More than people expect. Consistency in when you take a hormone preparation is genuinely significant. I can’t tell you what to take or when, that’s a GP or consultant question, but it’s worth asking specifically about timing, not just dosage. I started logging my own mood alongside cycle phase using the CareClinic app, mainly because the check-in reminders kept it actually consistent, and the patterns were clearer than I expected once a few months of data were there. If mood swings are disrupting daily life, document it properly and bring the record to your GP. That’s useful clinical information, not just venting.