"It's the second-by-second, minute-by-minute changes that really did it," said Davis, 39. "If you're the type of person who likes gadgets and devices and to collect metrics, you're also the kind of person who does not like gaps in data."
A pediatrician in Kansas City, Missouri, Natasha Burgert, said apps that track newborn feedings and sleep patterns have become wildly popular among her patients and she now encourages parents to send her the data before their appointments.
"In the first few weeks, parents are so tired. It's really hard for them to give you objective data," Burgert said.
Public health advocates and researchers say tracking technology could be used to encourage people to use less gasoline, conserve water or drive slower by giving them real-time feedback on their daily habits. It also could expose causes of medical conditions that baffle doctors.
HopeLab, based in Redwood, California, is one nonprofit looking to harness technology to improve health. It has developed a $30 movement-tracking device for kids called a "Zamzee," and a website that rewards activity with online points and badges.
HopeLab has developed video games for young cancer patients that lets them pretend to blast cancer cells. Researchers there say their studies have shown that the game improved patients' moods and encouraged them to stick with treatment.
"When you give people a sense of autonomy, a sense of agency, that can actually be very transformative to their health," said HopeLab spokesman Richard Tate.
Ramirez said he thinks the next step will be embedding sensors in nearly everything a person encounters throughout the day and linking that information together. Think of a car that won't start if you've consumed too much alcohol or a light bulb that changes colors when it's time to go to bed.
Industry watchers say these kinds of data-driven apps are finding their place in a market that has struggled to profit from advertising.
Raj Aggarwal, chief executive of Localytics, a Boston-based analytics firm, says mobile games are still by far the most popular among consumers, but their fan base can be fickle. If a data-logging app is useful enough, it can convince consumers that they should pay for upgraded subscriptions or premium services that earn the developers money.
One mobile app called "GymPact" has found a novel way of making money off its consumers' data. The app lets people bet against one another as to whether they will go to the gym. The non-exercisers have to pay the exercisers, with GymPact taking a cut.
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