Tim O'Reilly tweeted: "Quantified self for caffeine addicts — IOS app to optimize intake. (Didn't know half-life in body was 5 hours!)"
Two doctors at Penn State University have developed Caffeine Zone, a free iOS app that tells you the perfect time to take a coffee break to maintain an optimal amount of caffeine in your blood — and, perhaps more importantly, it also tells you when to stop drinking tea and coffee, so that caffeine doesn't interrupt your sleep.
How to optimize your caffeine intake