The Science
PMS Explained: How and Why it Happens
Craving chocolate a week before your period? Science has all the answers!
Premenstrual Syndrome, or PMS, is a very real, very common experience that impacts nearly half of women in their reproductive years globally.1 Women can often face symptoms intense enough to throw a wrench in their everyday lives! From issues like weight gain, bloating, and breast tenderness, to headaches, mood swings, and anxiety,1 the chaos is real.
But first, let’s break down what’s happening to your body throughout your menstrual cycle.
The Four Phases of the Menstrual Cycle
Every month, your hormone levels fluctuate to prepare your body for pregnancy, moving through four important phases:
1. Menstrual phase
Your body sheds its uterine lining, leading to your period.
2. Follicular phase
Rising estrogen levels stimulate the growth of follicles in the ovaries, preparing for ovulation.
3. Ovulation
A surge in your luteinizing hormone (LH) triggers the release of a mature egg from the ovary.
4. Luteal phase
Progesterone levels rise to support a potential pregnancy. If none occurs, hormone levels drop, leading to the next cycle.
Sound’s confusing, right? Don’t worry – we’ll explain all the complicated words up ahead. However, just remember this: PMS occurs during the luteal phase, right before menstruation begins, and disappears within a few days of the onset of your periods.
PMS is a complex condition with no single cause, but several biological and lifestyle factors play a role. While the exact cause of PMS remains unclear, researchers believe the syndrome is closely linked to hormone and neurotransmitter imbalances.
What Causes PMS?
Estrogen and progesterone are the two primary female sex hormones that regulate your menstrual cycle.
Estrogen helps develop and maintain reproductive organs, regulates mood, and influences serotonin levels (your ‘feel-good’ neurotransmitters).
Progesterone prepares the body for pregnancy and has a calming effect, balancing estrogen’s stimulating effects.
Research suggests that an imbalance between these hormones – such as estrogen dominance (too much estrogen) or progesterone deficiency (less progesterone)– could contribute to PMS symptoms,2 like mood swings, bloating, and fatigue.
Understanding PMS Triggers
PMS doesn't just 'happen' – it's driven by hormonal shifts, brain chemistry, and much more than we understand. Let’s explore some of the key triggers behind it:
Hormonal fluctuations
During your cycle's luteal phase, progesterone levels peak and then rapidly decline, which can cause mood-related symptoms, like anxiety or irritability. Estrogen, which has a strong connection to mood regulation, also drops, affecting neurotransmitters that influence emotional wellbeing.
Chemical changes in the brain
Brain chemicals, better known as neurotransmitters, help control your mood, emotions, and sleep. Estrogen plays a role in keeping these chemicals balanced. When estrogen drops, it triggers an increase in norepinephrine (a stress-related chemical), which lowers serotonin (the ‘feel-good’ chemical), dopamine (the ‘motivation’ chemical), and acetylcholine (which boosts focus and memory). This can lead to mood swings, disturbed sleep, anxiety, etc.
Underlying mental health conditions
Women with depression, anxiety, or a family history of mood disorders, including bipolar disorder and postpartum depression, may be more prone to experiencing PMS, PME, or PMDD. Moreover, stress amplifies sympathetic nervous system activity, aka your body's fight-or-flight response, making your uterus contract more, which can then (unfortunately) lead to painful menstrual cramps.
Lifestyle factors
A study found that women who consumed excessive sweets, junk food, and coffee had a higher risk of PMS!2 Similarly, research on university students revealed that a sedentary lifestyle, poor sleep, and an unhealthy diet increased the likelihood of PMS.3 Certain habits can worsen PMS symptoms, like:
Smoking
Eating high-fat, high-sugar, or salty foods
Avoiding physical activity or exercise
Sleeping poorly
Note
If you or someone that you love is dealing with PMDD, you're not alone. Reach out to your nearest healthcare professional or gynaecologist! Talking to them can help you find the clarity and support you truly deserve.
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