The Menstrual Cycle Explained: Phases, Hormones & What’s Normal

Why Understanding Your Cycle Matters

The menstrual cycle is often reduced to “having a period”, but in reality it is a complex hormonal rhythm that influences mood, energy, sleep, appetite, pain, and mental health.

Understanding the names, phases, and hormones of the cycle helps women:

Recognise what’s normal (and what isn’t)
Spot early signs of hormonal imbalance
Advocate for better healthcare
Understand conditions like PMS, PMDD, PCOS, and endometriosis

This guide explains the menstrual cycle in a clear, evidence-based, woman-centred way.

What Is the Menstrual Cycle?

The menstrual cycle is the monthly hormonal process that prepares the body for a possible pregnancy. It is measured from Day 1 of bleeding to the day before the next period starts.

Average cycle length: 21–35 days
Cycles vary between individuals, regularity matters more than exact length

The cycle is divided into four phases, each driven by different hormones.

The 4 Phases of the Menstrual Cycle

1. Menstrual Phase (Bleeding Phase)

Approx. Days 1–5

What’s happening:

Estrogen and progesterone are at their lowest
The uterus sheds its lining (your period)

n experiences:

Low energy
Desire for rest and solitude
Cramping or back pain
Emotional sensitivity

What’s normal:

Bleeding 3–7 days
Mild to moderate cramps

Not normal:

Bleeding longer than 7 days
Severe pain that disrupts daily life

2. Follicular Phase

Approx. Days 1–13 (overlaps with your period at first)

Key hormone: Estrogen (rising)

What’s happening:

The brain signals the ovaries to prepare an egg
Estrogen begins to rise, rebuilding the uterine lining

Common experiences:

Increasing energy
Clearer thinking
Motivation and optimism
Improved mood

This is often a great phase for planning, learning, and decision-making.

3. Ovulatory Phase

Approx. Day 14 (varies)

Key hormones: Estrogen (peak), Testosterone (small surge)

What’s happening:

An egg is released from the ovary
Fertility is highest (but this phase is not just about fertility)

Common experiences:

Confidence and sociability
Increased libido
Clear communication
Feeling “like yourself again”

Ovulation also supports bone health, brain health, and cardiovascular protection.

4. Luteal Phase

Approx. Days 15–28

Key hormone: Progesterone

What’s happening:

Progesterone rises to support a potential pregnancy
If pregnancy doesn’t occur, progesterone and estrogen fall

Common experiences:

Calmer energy initially
Then possible irritability, fatigue, anxiety, or low mood
Increased appetite or cravings
Sleep disruption

This phase is where PMS and PMDD symptoms appear.

What’s Normal vs Not Normal Across the Cycle

Common but NOT Normal:

Debilitating pain
Extreme mood changes
Heavy bleeding (soaking pads hourly)
Severe anxiety or depression before periods
Irregular or missing cycles (outside perimenopause)

These symptoms are often dismissed — but they may signal hormonal conditions.

How the Cycle Changes Over Time

Hormonal patterns are not static.

From 35+, subtle perimenopausal changes may begin
Ovulation may become less consistent
Progesterone often declines first, affecting mood and sleep

Conditions Linked to the Menstrual Cycle

Understanding cycle phases helps contextualise:

PMS – hormone-linked symptoms in the luteal phase
PMDD – severe mood symptoms driven by hormonal sensitivity
PCOS – irregular ovulation and androgen imbalance
Endometriosis – pain not explained by cycle norms

(Each deserves its own deep dive — and we’re building those.)

FAQs

Q: Is it normal to feel anxious before your period?
A: Mild emotional changes can be normal, but persistent or severe anxiety may indicate progesterone sensitivity, PMS, PMDD, or perimenopause.

Q: Can you have a regular cycle and still have hormonal issues?
A: Yes. Regular bleeding does not always mean healthy ovulation or hormone balance.

Q: Do cycles change during perimenopause?
A: Yes. Cycles may shorten, lengthen, or become unpredictable from as early as 35+.