Description

Track your caffeine like your body actually processes it.

HalfLife is a real-time caffeine tracker for Pebble that simulates how caffeine is absorbed, peaks, and wears off — so you can stay energized, avoid crashes, and sleep better.

    Note: This is a mathematical model, not medical advice.

> Why It’s Different

Most apps just estimate. HalfLife simulates using a pharmacokinetic model, it tracks your caffeine levels continuously — so you always know where you stand, not just what you drank.

> What You Get
  - Real-time caffeine levels: updates every second — no static estimates.
  - Peak prediction: see when your caffeine will hit hardest — and how strong it’ll be.
  - Smart sleep guidance: know when your levels are low enough for quality sleep.
  - 6 Custom drink presets: save your go-to coffee, tea, or energy drinks.
  - Flexible drinking durations: 3 presets of 5 to 120 minutes
  - Preferred caffeine range: Stay in your ideal focus zone at a glance.
  - Free-form logging: enter any caffeine amount anytime.

> Built Around You

Everyone processes caffeine differently. HalfLife lets you adjust:

  - Caffeine half-life (how fast it leaves your body)
  - Absorption speed (how fast it gets absorbed into your bloodstream)
  - Your personal sleep threshold
  - Your preferred caffeine range (color display watches only)
  - Or just use the built-in defaults and go.

> Real-World Uses
  - Time your morning coffee for peak focus
  - Avoid the afternoon crash
  - Don’t ruin your sleep with late caffeine
  - Plan pre-workout energy boosts
  - Understand how multiple drinks stack over time

> Private & Efficient
  - 100% on-device – your data never leaves your watch
  - No background drain – zero battery impact when closed
  - Open source – transparent and customizable

> Coming Soon
The core model is solid, but I still have some exciting plans for the future:

  - Redesigned UI: A visual "glow-up" is the top priority, including support for round Pebble watches. (Already making minor progress, but I'm a bioinformatician, not a designer — so bear with me.).

  - Edit active drinks: In case you set the wrong amount or duration, this feature will allow you to edit and delete your current drinks.

  - Shake For Help: Shake the watch on any screen of the app for a guide on the controls and meaning of values. (With an option to disable this if you already know what's what).

  - On-watch configuration: Configure most settings without needing to grab your phone.

  - “Preview before you drink” feature: See how a drink will affect your levels before you log it.

  - Drink planning: Plan you day's caffeine for workouts, productivity or to regulate your levels in advance. Get notifications for the drinks you scheduled when viewing the caffeine graph across 12-72 hours.

  - Closed-Loop Model: When the new Pebble hardware arrives, the plan is to use advanced heart rate (specifically HRV) data to create a self-tuning model that adapts to your body's unique response. This allows for a broad array of additional features.

Note: Values in screenshots have been tampered with to show off the features. 

Have a feature idea or found a bug? The code is open and contributions are always welcome! (Also some extra details on the model coming soon for the science nerds)
https://github.com/FPuzeras/HalfLife