Why do I get mood swings before my period?

Because in the days before your period, oestrogen and progesterone both fall sharply, and that fall reaches beyond your ovaries into the same brain chemistry that regulates mood. For most women, some irritability, tearfulness or a shorter temper in the week before bleeding starts is a normal, common part of the cycle, not a sign that anything is wrong.

• Oestrogen supports serotonin, and oestrogen falls fastest right before your period. Serotonin is one of the brain chemicals most closely tied to mood, and both the NHS and Mayo Clinic list fluctuating hormones and brain chemistry among the drivers of premenstrual mood symptoms.
• Progesterone's fall plays a part too. As progesterone drops, so does allopregnanolone, a byproduct of progesterone that normally has a calming effect on the brain similar to an anti-anxiety medicine. A review in The Lancet points to how sensitively the brain responds to this rise and fall across the cycle, rather than the absolute hormone level, as central to premenstrual mood change.
• It clusters in the same window as your other premenstrual symptoms. The same days that can bring on the exhaustion many women feel before their period and the headaches some get in the same window are, for many women, when mood symptoms show up too.
• It is common, and usually mild. ACOG lists irritability, anxiety, tearfulness and mood swings among the most frequently reported PMS symptoms, alongside physical ones like the breakouts many notice in the same window and the breast tenderness many notice in the same window.

For a smaller group of women, this goes further than moodier. Premenstrual dysphoric disorder (PMDD) causes mood symptoms, marked irritability, anxiety, low mood or a sense of being overwhelmed, severe enough to disrupt work, school or relationships in the two weeks before a period, then lift once bleeding starts. ACOG and the NHS both treat PMDD as a distinct, diagnosable condition with its own treatment options, separate from ordinary PMS, so it is not something to just push through.

Tracking is worth doing here more than for almost any other premenstrual symptom, because the single most useful thing you can bring to a doctor is whether the mood change is actually cyclical, appearing and lifting on a predictable schedule, or present all month regardless of where you are in your cycle; three cycles of tracking is usually enough to show the pattern. A tracker built around a Muslim woman's actual cycle, one that logs mood against the day you are on rather than just a date, makes that record easy to produce; the best period tracker for privacy covers what to check before it holds a record this personal.

Speak to a doctor if mood symptoms are severe enough to disrupt your daily life, if they do not ease once your period starts, or if lifestyle changes have not helped after a few cycles. Get help immediately, from a doctor, a crisis line or emergency services, if you ever have thoughts of harming yourself: that is a mental health emergency, not something a cycle tracker or a lifestyle change is equipped to handle on its own.