The menstrual cycle is often reduced to “your period,” but in reality, it’s a month-long hormonal symphony. Each phase is orchestrated by changes in estrogen, progesterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and even testosterone. These hormones regulate the reproductive system and influence brain chemistry, sleep patterns, appetite, energy levels, stress response, and emotional well-being.
Understanding this cycle isn’t just about fertility; it’s about recognizing how biology affects mental health and learning to move with those rhythms rather than against them.
Phase 1: Menstrual (Days 1–5)
Hormones:
- Estrogen and progesterone are at their lowest
- FSH begins to rise, signaling the ovaries to start developing new follicles
Brain and mood effects:
- Low estrogen means reduced serotonin and dopamine activity which can contribute to low mood, irritability or fatigue
- Some people describe mental fog or decreased concentration during this phase
- The drop in progesterone removes its calming effect on GABA, which may add to sleep difficulties or anxiety in sensitive individuals
Body:
- Menstrual bleeding occurs as the uterine lining sheds
- Common symptoms include cramps, headaches and fatigue
Helpful strategies:
Prioritize rest, hydration and iron-rich foods. Gentle exercise can increase endorphins and improve mood.
Phase 2: Follicular (Days 6–14)
Hormones:
- Estrogen rises steadily as ovarian follicles mature
- FSH continues its role in follicle growth
- Progesterone stays low
- Testosterone begins to rise gradually toward ovulation
Brain and mood effects:
- Estrogen boosts serotonin, dopamine and even BDNF (brain-derived neurotrophic factor) which supports neuroplasticity. This translates into better mood, motivation, learning and memory
- Rising testosterone can improve assertiveness, confidence and libido
- Many studies link higher estrogen levels with enhanced verbal memory, social fluency and problem-solving
Body:
- Energy rises, exercise performance improves and skin often looks clearer
- Many feel their most resilient and productive in this phase
Helpful strategies:
This is an ideal time for starting projects, brainstorming ideas and tackling challenges. Use the extra energy and mental clarity to your advantage.
Phase 3: Ovulation (Around Day 14)
Hormones:
- Estrogen peaks, triggering the surge of LH that causes ovulation
- FSH also spikes briefly to support the release of the egg
- Testosterone reaches its monthly high
- Progesterone begins to rise slightly after ovulation
Brain and mood effects:
- Peak estrogen strongly enhances dopamine and serotonin activity, which can elevate mood and increase motivation
- High testosterone further supports confidence, sexual desire and social drive
- Studies show estrogen at this stage may sharpen verbal skills, empathy and social awareness, which could be evolutionarily linked to fertility signaling
Body:
- Many feel their most attractive, energetic and outgoing
- Libido peaks
- Some experience mittelschmerz (brief ovulation pain)
Helpful strategies:
Schedule important conversations, social events or performances during ovulation if possible. Your brain and body are often primed for connection and high performance.
Phase 4: Luteal (Days 15–28)
Hormones:
- After ovulation, the corpus luteum forms and produces high levels of progesterone
- Progesterone dominates this phase with estrogen rising again briefly then falling
- Testosterone declines after its ovulatory peak
- Toward the end of the luteal phase, estrogen and progesterone both drop sharply if pregnancy does not occur
Brain and mood effects:
- Progesterone enhances the calming neurotransmitter GABA early in the luteal phase, which can support sleep and relaxation for some
- As both estrogen and progesterone drop in the late luteal phase, serotonin activity decreases which can trigger mood swings, irritability, anxiety or depression (PMS or PMDD)
- Lower testosterone may also reduce libido, energy and assertiveness compared to earlier in the cycle
- Research shows that women with PMDD may have altered sensitivity in brain regions (like the amygdala and prefrontal cortex) to these hormonal shifts
Body:
- Physical symptoms may include bloating, breast tenderness, cravings, headaches and sleep disruption
- Many experience a sense of heaviness or lower stamina
Helpful strategies:
Prioritize sleep hygiene and stress management. Light exercise, meditation and mindful nutrition (balanced carbs, protein and magnesium-rich foods) can help regulate symptoms. For severe PMS or PMDD, professional care can include SSRIs, hormonal therapies or lifestyle interventions.
The Role of Testosterone Throughout the Cycle
While often overlooked, testosterone plays an important role in the menstrual cycle. Though women produce much lower levels than men, fluctuations across the month influence mood, energy, and sexuality.
- Follicular phase: Testosterone gradually rises, boosting energy, assertiveness and sexual desire
- Ovulation: Peaks at mid-cycle, enhancing libido and confidence
- Luteal phase: Declines, which may contribute to decreased motivation or lowered mood for some
This flow adds another layer to how mental health and relationships may feel different depending on where you are in your cycle.
Why All of This Matters
Hormones are powerful messengers that don’t just regulate reproduction — they shape how your brain works. Estrogen supports mood through serotonin and dopamine. Progesterone calms through GABA. Testosterone fuels confidence and desire. LH and FSH choreograph the timing of it all.
When you understand these patterns, you can anticipate changes instead of being blindsided. You can give yourself grace when your brain chemistry is working against you and take advantage of the windows where it’s working for you.
Resources for Deeper Learning
Our Bodies Ourselves – ourbodiesourselves.org
Office on Women’s Health – womenshealth.gov
International Association for Premenstrual Disorders – iapmd.org
Takeaway: The menstrual cycle is a finely tuned hormonal rhythm that affects not only fertility but also mood, energy, sleep, and mental health. By understanding the roles of estrogen, progesterone, testosterone, LH, and FSH across each phase, you gain the power to live in sync with your body rather than in conflict with it.
TalkHER.org 
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