Launched my first health app after 6 years in SaMD (Software as Medical Device): an adaptive caffeine optimizer app for iOS

My recent professional background has been in developing SaMD and after being out of work for several months I decided I needed to do something that's more stimulating than sending out application after application. I also wanted to work on something that (selfishly) would help me find my sleep and energy back by helping me time and dose my caffeine intake better. At the beginning of the year I was sleeping really poorly, feeling very anxious, and frequently crashing in the afternoon. Now I feel like my energy levels have completely shifted. During this time I've found a curious (and way less risky) parallel with insulin dosing and timing.

I ended up building an iOS app called Caffeinly ( https://apps.apple.com/us/app/caffeinly-sleep-energy/id6771882780 ) after not feeling too impressed by the crude manner in which caffeine pharmacokinetics were being modeled in other apps.

I spent a good chunk of two months developing and refining the pharmacokinetic model itself, while also building in features that helped me log caffeine intake with low effort, finding my daily cut-off time to protect sleep, avoiding anxiety and jitters, and predicting potential afternoon crashes.

Still so many ways in which I can keep refining the model but at this point I need to start getting real user data so that I can differentiate between what I think is cool, vs what is actually useful to people.

It's been really fun using modern AI tools to simulate the different roles I used to interact with in a professional medical device development setting.
I'm curious if anyone else has done something similar and what your experience has been with health-related side projects. Also happy to answer any questions about the app or caffeine PK-modeling and sleep quality correlation.