Menstruation is the cyclical, orderly shedding of the uterine lining, responding to hormonal interactions from the hypothalamus and pituitary glands in your brain, and the ovaries of your reproductive system. This phase typically lasts between four to six days, but commonly ranges from two to eight days, and involves the shedding of blood, mucus, and cells from the uterine lining. Most researchers would consider it to be a sub-phase of the follicular phase based on its hormone profile.

• Hormonal changes: Both oestrogen and progesterone levels are low at the start of menstruation.
• Common symptoms: Abdominal cramps, bloating, breast tenderness, fatigue, mood swings, headaches, back pain, and digestive issues like diarrhoea or constipation.

How do these changes impact the brain?

During menstruation, declining levels of oestrogen and progesterone reduce serotonin levels in the brain. Serotonin is crucial for stabilising mood and regulating pain perception. This decrease in serotonin not only makes you more susceptible to feeling pain but also can contribute to mood swings or general feelings of sadness or irritability.