I am an irregular coffee drinker. I don’t need it to get up in the morning, but I do need it after a rough night or a heavy lunch. I am also, though, an irregular sleeper. Some nights I find myself wide awake at 3 a.m. Could it have been that cup of coffee I had after lunch? Should I have had tea instead? Would that have been enough to get me through the afternoon?
Well, now, as they say, there’s an app for that: Caffeine Zone, based on research on the “pharmacokinetics of caffeine.” You enter how much coffee or tea you’ve had, when you had it, and how quickly you drank it, then the app sends you an alert when you might need another cup to keep you sharp. It also warns you when the coffee you’re about to have might keep you up at night. On a graph, it maps the amount of caffeine in your body against color-coded zones corresponding to the compound’s metabolic effects.
According to Frank Ritter, the Penn State cognitive scientist who thought up the app, one of the lessons it teaches is that, like many other daily drugs—antibiotics, for example, or nicotine—caffeine is most effective when intake is front-loaded. The first coffee of the day should be the biggest, and drunk the fastest, for a big bump, and the rest of the day’s doses should be smaller and ingested more slowly. You want to stay in that optimum range. “You don’t want to have these big pulses of a whole cup,” he emphasizes. “I say cold coffee is good.” It’s trajectory management: Launch rocket, achieve desired altitude, maintain orbit with tweaks.
According to my Caffeine Zone app, as I write these words 35 minutes after my first sip of Starbucks house blend, I have just entered the forest-green band of optimum cognition. If I don’t re-caffeinate within the hour, I will drop out of the zone. I inform Caffeine Zone 45 minutes later that I am about to redose with a large 16 oz. coffee. The app warns me this will actually launch me past the upper boundary of the “Max Optimal” zone (200 mg of caffeine per kilogram of body weight). It will also keep me wired past 11:30 p.m., the time I entered as my bedtime.
The problem with the way many coffee-drinkers manage their intake, Ritter says, is they don’t think cumulatively. A small coffee at 2 p.m. isn’t going to keep most people up at night, but it will if there’s still caffeine coursing through the system from an earlier couple of cups. Ritter himself thinks nothing of ordering a two-thirds decaf cup of coffee, even a three-quarters decaf cup. “It’s hard for us to do the math because it requires a lot of exponential calculations, but your body does it,” he says. So does Caffeine Zone.
I opt instead for a Cherry Coke with lunch. There is no button for caffeinated soda (there is, strangely, a button for caffeinated gum), but there is a custom feature that allows me to enter Cherry Coke’s dose information and my intake speed (usually the time it takes me to walk from the soda machine upstairs to my desk, which I round up to 5 minutes). My Coke’s measly 34 mg of caffeine, it turns out, will barely keep me above the 150 mg/kg lower bound of the optimum zone. So I add a medium cup of tea after lunch, which keeps me in the optimum zone for much of the afternoon but will, Caffeine Zone predicts, keep me up for an extra half-hour tonight. That’s O.K., 11:30 was sort of an aspirational bedtime anyway.
Of course, the next step might be to connect the iPhone to a caffeine drip and just have it pump a few dozen milligrams of caffeine directly into a vein when I begin to flag. Or maybe I could rig the app to sync with my workstation and track my typing speed, dosing me when I slow, or when it notices I have spent more than five minutes on YouTube. Where do these strange, idle thoughts come from? My iPhone chimes as Caffeine Zone warns me that I have dropped out of the optimum zone. Time for that cup of tea.