Does mood swings get worse before your period during perimenopause?

Yes, mood swings frequently intensify in the days before your period during perimenopause, and the biology behind this is well understood. This is the classic premenstrual pattern amplified by the wider hormonal swings that define perimenopause. Many women who managed PMS reasonably well in their thirties find that the same premenstrual window becomes significantly harder to navigate in their forties.

The hormonal mechanism works on two fronts. First, estrogen drops in the days before menstruation. Estrogen supports serotonin production and receptor sensitivity, so as estrogen falls, serotonin availability decreases. Serotonin is a primary mood-stabilizing neurotransmitter, and its reduction in the late luteal phase is a core driver of premenstrual irritability, low mood, and emotional reactivity. Estrogen also supports dopamine activity, which influences motivation and reward processing. When both serotonin and dopamine take a hit simultaneously, the emotional effect is noticeable and real.

Second, progesterone metabolizes into allopregnanolone, a compound that acts on GABA-A receptors in the brain. For most women this has a calming, slightly sedating effect. But research by Bixo et al. (2017) demonstrated that women with premenstrual dysphoric disorder (PMDD) show a paradoxical response to allopregnanolone, experiencing anxiety and irritability instead of calm when this compound fluctuates. This GABA sensitivity appears to be a neurological vulnerability, not a character trait, and it can emerge or worsen during perimenopause when hormonal swings become more pronounced and the brain's regulatory systems are under greater strain.

During perimenopause, these premenstrual mood dips are often worse for two interconnected reasons. Cycles become irregular, and anovulatory cycles (where no egg is released) result in little to no progesterone being produced, leaving estrogen relatively unopposed and then dropping sharply before menstruation. At the same time, the overall amplitude of estrogen fluctuations increases compared to the reproductive years. Higher peaks followed by steeper drops mean the withdrawal effect on serotonin is more extreme. The result is that the premenstrual week, which may have been predictably difficult before, can become significantly more emotionally destabilizing.

Sleep disruption compounds the picture. Declining progesterone reduces the GABA-mediated calming effect that supports deep sleep in the luteal phase. Night sweats, which often worsen before menstruation as the thermoregulatory threshold shifts, fragment sleep further. Sleep deprivation directly impairs emotional regulation by reducing activity in the prefrontal cortex and increasing amygdala reactivity, which is the biological equivalent of losing access to your rational brain while your emotional responses are amplified.

What actually helps: Aerobic exercise has solid evidence for its mood-supporting effects via endorphin release and serotonin activity, and even moderate exercise in the luteal phase can reduce premenstrual emotional intensity. Stable blood sugar matters too, as blood glucose dips amplify emotional reactivity and make irritability harder to manage. Eating protein and complex carbohydrates at regular intervals helps buffer against sudden mood drops. Reducing alcohol in the premenstrual window is important, since alcohol disrupts both sleep and GABA function and can markedly worsen next-day mood and emotional regulation. Magnesium, specifically magnesium glycinate, has some evidence for reducing premenstrual anxiety and irritability.

Tracking mood scores alongside your cycle days in PeriPlan can reveal whether a clear premenstrual pattern exists. This data is also genuinely valuable to bring to a healthcare provider, because it helps distinguish cyclical mood changes from generalized depression or anxiety, which require different treatment approaches.

One practical strategy that some women find helpful is adjusting expectations and scheduling around the premenstrual window rather than fighting against it. If you know that days 24 to 28 of your cycle tend to be emotionally harder, you can plan fewer high-stakes social interactions, reduce your workload where possible, and build in more recovery time. This is not avoidance but rather intelligent cycle literacy. Knowing the pattern is temporary and hormonally driven, rather than a reflection of who you are, can also reduce the shame and confusion that make these episodes feel worse than they need to.

When to see a doctor. If premenstrual mood swings are so severe that you are struggling to maintain relationships, fulfill work responsibilities, or keep yourself and others safe, please seek help promptly. PMDD is a recognized clinical condition with effective treatments including SSRIs (which can be taken only during the luteal phase, not daily), hormonal approaches that reduce the amplitude of fluctuations, and psychotherapy. Perimenopausal hormone therapy can also reduce the amplitude of the hormonal swings driving these symptoms. These are not conditions to manage through willpower alone, and effective treatment options exist.

This content is for informational purposes only and does not replace medical advice. Always consult your healthcare provider about your specific situation.