VitaSine

VitaSine is an honest biorhythm journal. Traditional biorhythm theory models each day as three overlapping cycles — physical (23 days), emotional (28 days), and intellectual (33 days) — running from the moment of your birth. The idea is historically interesting and fun to watch, but when biorhythms have been tested scientifically, they have not been shown to predict performance, health, accidents, or mood better than chance. Use VitaSine as a reflective journaling companion, not as medical, safety, or decision-making advice. What makes VitaSine different is your personal curve: each day you submit a short self-report per cycle, and VitaSine fits a personalized sinusoid to your own reports, shown alongside the textbook curve. Over time you can watch the two curves converge, diverge, and drift in ways that reflect how you actually feel. Features - Up to five persons tracked on one chart, with color-blind-safe overlays. - Per-cycle daily self-reporting with up to fourteen days of backfill. - Personal curve fitted with recency-weighted least squares, free to drift from the textbook period based on your reports. - Local-only storage. No cloud sync, no accounts, no analytics. - Universal iPhone and iPad, VoiceOver and Dynamic Type supported. - Exports all your data as a single JSON file whenever you want. Privacy No data is collected or transmitted by this app. All information stays on your device. The app makes zero network calls after install and ships with no third-party SDKs.