I hit a nice little gold mine for my iPhone today. Being the first day to play with it, I will tell you about the app… then report back after playing with it for a week at work.
The app, Caffeine Zone2, has you enter when you drink things with caffeine in it… mostly in the area of coffee and tea based drinks. From that information, you will be alerted when the caffeine (per the apps calculations) in your body has dropped down and a coffee might get your energy back up. Note that Caffeine Zone2 does have a disclaimer saying the apps recommendations comes from calculations and no real blood testing is done.
Along with when you might want to drink a cup of coffee, Caffeine Zone2 will also calculate when the last cup of coffee for the day should be based on when you plan on going to bed. The app will warn you when you enter the drink information… so to make a decision from the information you should enter your caffeine intake prior to drinking.
The app uses your body weight to help make decisions, but there is no way to enter if you where (or what) eating when drinking your coffee. The presets for drinks in Caffeine Zone2 include 3 drink sizes and defaults for how long it took you to drink. If you are drinking espresso drinks, there is an option to put in the mg of the drink… I looked around and found “The USDA value for Espresso coffee is 64 mg caffeine per fluid ounce.” on this site.
You do get a nice graphic that shows a rise when you drink, tapering off over time. A downward line crossing the center line will be an impact on your energy and the blue area is sleep time. Use your finger to slide left/right through time.