The science of hormones, mood and the menstrual cycle. Plain language, real research, no fluff.
Your stress system and your cycle share a hypothalamus. Cortisol delays ovulation and stretches the cycle, and the late luteal hands you less of the chemistry that makes pressure manageable.
As the lining of the uterus breaks down it releases prostaglandins, which make the uterine muscle contract. Those contractions briefly squeeze the blood vessels running through it, and that is what registers as cramping.
Estrogen falls and oxytocin signalling weakens while the amygdala gets more reactive. Same partner, different filter.
Estrogen drops, testosterone holds steady, and the shifting ratio tells your sebaceous glands to produce more oil. It is a ratio, not your routine.
Worse sleep, a metabolic rate 5 to 10% higher, and allopregnanolone withdrawing. Three separate drains, all landing in the same week.
Peak estrogen, a brief testosterone rise, and a reward system responding more strongly than usual. The good week has a mechanism too.
Testosterone peaks at ovulation. Progesterone dampens libido in the luteal. Same body, different chemistry, very different sex drive across the month.
Estrogen drops, serotonin drops, and the brain reaches for the fastest food it knows that brings serotonin back up. The craving is real biology.
Your basal metabolic rate actually rises 5 to 10% in the luteal phase. You're burning more, so you need more. The hunger is proportional to a real metabolic change.
Premenstrual anxiety has a specific biological cause: the sharp drop in allopregnanolone disrupts the brain's calming system. Same receptors as anti-anxiety meds.
Amygdala reactivity goes up, prefrontal regulation goes down. Catastrophic thinking feels real because the brain is processing it as real.
Crying easily in the luteal phase isn't fragility. It's a measurable lowering of the emotional threshold caused by three hormonal drops at once.
The science of cycle-related brain fog: estrogen, allopregnanolone, and why focus dips in the late luteal phase. Evidence-based interventions that actually work.
Sleep is sensitive to hormonal change. Body temperature, GABA, serotonin and inflammation all shift across the cycle, and they all affect sleep. Here's how, and what helps.
Naming a feeling reduces its intensity. Brain science explains why. And why cycle awareness alone has been shown to reduce psychological distress in PMS.
The hormones behind each cycle phase (menstrual, follicular, ovulatory, luteal) and how each one shows up in your mood, energy and sleep. Also known as Inner Seasons.
If your hardest week consistently lines up with the days before your period, it isn't a coincidence. The science behind PMS, allopregnanolone, and the late luteal drop.
The long version: how progesterone turns into the calming compound your body relies on, why your brain adjusts to having a lot of it around, and what happens when it falls away.
Most personal patterns become visible after 2 to 3 cycles of consistent tracking. Here's what shows up when, and what makes the whole thing go faster.
Only about 13% of cycles are exactly 28 days. Here's the research on what's normal, why your cycle varies, and how variation is the norm not the exception.
Cycle changes in perimenopause, what your sleep does across the month, and the cycle's effect on cognition. We're working on them.