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New app gauges ideal time for coffee break

Developed at Pennsylvania State University, Caffeine Zone helps determine how much caffeine is coursing through your bloodstream at any given time.

The free Caffeine Zone app is available for iPhone, iPad, and iPod Touch. Screenshot by Elizabeth Armstrong Moore/CNET

If you're wondering whether you're too many cups or too many hours into the day for yet another jolt of caffeine, a free app developed by researchers at Pennsylvania State University aims to help.

In building the Caffeine Zone app, professors representing several disciplines relied on peer-reviewed studies to devise a simple formula: those with between 200 and 400 milligrams of caffeine in their bloodstream are in the optimal mental alertness zone, while anyone above 100 milligrams has entered the good-luck-sleeping-anytime-soon zone.

"Many people don't understand how caffeine levels in their bloodstream go up and how they go down," said Frank Ritter, himself a professor of so many things (information sciences and technology, psychology, and computer science and engineering) that he may have devised this app for his own sake.

Available on iPhone, iPad, and iPod Touch, the app relies on users to do the heavy lifting. They must manually input how much caffeine they have consumed, how much they plan to drink next, as well as when (and how quickly) they plan to drink it. Based on this data, the app advises whether and how much the user should drink.

Caffeine Zone's first several user ratings on iTunes aren't terribly favorable, with complaints about the app crashing when inputting a custom dose. Ritter says his team has found the bug in the code and hopes to have it fixed in just over a week.

And then there's the issue of whether those who would most benefit from this app will actually want to know if they've reached their daily limit (cough, my father). But for the rest of the caffeinated minions wondering whether that next cup will result in alertness or a busted sleep schedule, Caffeine Zone without the custom entry kinks is probably worth a shot.