# Lumen

> Lumen is a free, privacy-first cycle-aware productivity planner. It calculates your current menstrual cycle phase from your last period date and cycle length, then recommends which kinds of work (deep focus, presentations, learning, editing, reflection) are best aligned with each of the four hormonal phases (menstrual, follicular, ovulatory, luteal). All data lives in the user's browser; no accounts, no tracking, no server-side storage.

The four-phase model:

- **Menstrual (Reflect)**: cycle days 1–5, hormones at minimum, best for retrospectives and planning
- **Follicular (Build)**: days 6–13, rising estrogen drives neuroplasticity, best for learning and complex problem solving
- **Ovulatory (Connect)**: days 14–16, estrogen peak plus LH surge, verbal fluency peaks, best for presentations and hard conversations
- **Luteal (Finish)**: days 17–28, progesterone rises then drops, detail orientation peaks early, best for editing and closing tasks

Lumen is informational, not medical advice. It does not model hormonal contraception, perimenopause, PCOS, thyroid conditions, or pregnancy.

## Core pages

- [Lumen home](/): Free cycle phase calculator. Enter last period date, cycle length, period length → see current phase and weekly plan.
- [Methodology](/methodology): The science behind Lumen. Explains the four-phase model, recommendation logic, peer-reviewed source list, and limitations.
- [Privacy](/privacy): Lumen's privacy stance. No data collection, no tracking cookies, all cycle data stays in browser localStorage.
- [Terms](/terms): Plain-English terms of use. Lumen is informational only and not medical advice.

## Documentation

- [llms-full.txt](/llms-full.txt): Full content of all main pages concatenated for LLM ingestion.
- [Sitemap](/sitemap.xml): Machine-readable URL list.

## Optional

- [Open Graph image](/logo.png): Lumen logo and brand mark.