The power nap app is done. Two weekends of building, submitted to the App Store, currently in the hands of whatever Apple reviewer pulls the short straw. Check out n2nap.com to see what it does.
What I built
N2nap is an Apple Watch app that does one thing: it waits for you to fall asleep, then starts your nap timer. You pick how long you want to nap (10, 15, 20 minutes, or custom) and the app monitors your heart rate and wrist motion to figure out when you've actually drifted off. Once you're out, the countdown begins. When time's up, it buzzes you awake. No groggy oversleeping. No mental math. Sleep detection uses a dual-gate system. Gate A watches for a simultaneous drop in heart rate and sustained stillness. Gate B uses wrist angle stability as a secondary signal. Both gates require a confirmation window before triggering, so adjusting your pillow doesn't convince the app you've woken up and send it back to square one. When onset is confirmed, the app backdates to when stillness actually started. You get credit for the sleep that already happened. It's polite like that.