Evidence-based articles about your cycle, body, nutrition, and wellbeing. Written for real women and their partners.
Track Your Cycle Free89 days Pro free in Telegram
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More than 10 000 women are tracking their cycle in Luna right now
It's a red flag for endometriosis. See a gynecologist if painkillers don't help.
Consistency from month to month matters more than the exact length.
Chronic stress and low calories can cause hypothalamic amenorrhea.
Luna's algorithm needs at least one full cycle of data.
Glycinate form is best-tolerated. Discuss with your doctor.
The menstrual cycle is a 21-35 day hormonal arc, not just a few bleeding days. Estrogen, progesterone, LH and FSH shift weekly, and they don't only control fertility. They also drive your energy, mood, sleep, skin, appetite and even how your body responds to exercise. Understanding the pattern is one of the highest-leverage things you can do for your health.
Luna treats your cycle as a daily companion, not a calendar entry. We give you predictions that adapt to your real data, phase-specific tips, and a private place to log mood and symptoms. The articles below cover the foundations: the 5 phases, hormones, fertility, PMS, irregular periods, and how to support a partner who's tracking too.
Everything is evidence-based. We cite ACOG, RCOG, NICE and NHS where it matters. The content was reviewed by board-certified OB-GYN consultants in May 2026.
Log the first day of bleeding. That is day 1, and it is the only entry a first prediction needs. After two or three cycles the pattern is usually clear enough to forecast from. Mood, pain and discharge are optional β they become useful later, when you want to know why a month felt different.
Count from the first day of your last period. Roughly: days 1β5 menstruation, 6β13 follicular, ovulation around day 14, then the luteal phase until the next period. Those numbers shift with your own cycle length β it is the first half that stretches and shortens, while the luteal phase usually holds at 12β14 days.
A few days either side is ordinary. Illness, travel, short sleep, a sudden jump in training load and stress all move the date. What is worth looking into is a pattern: three cycles missed in a row, or a rhythm that changed abruptly and stayed changed.
More, not less. The prediction is wider and less certain, but the record is the thing a doctor actually needs β a history of real cycle lengths turns βit's all over the placeβ into a range somebody can work with.
Yes. Luna has a partner mode that shows the current phase and what tends to help during it, without exposing your notes or your symptom log. You decide what is shared, and you can stop sharing at any point.
No. Every article is free, open and needs no account. The app is for the tracking and the predictions; the guide stands on its own and always will.
Why stress can shift a cycle after a breakup, and what happens to emotional state afterwards. Browse the full section →
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