At DailyFeats.com, users can get points for performing healthy tasks, such as working out and eating vegetables. Credit: DailyFeats.com

The office walls of Zeo, a startup that has developed a consumer device to monitor sleep, sport large portraits of grinning employees displaying their sleep scores. (The calculation incorporates total sleep time, number of awakenings, and time in different phases of sleep.)

After giving a visitor a tour of the office, cofounder Ben Rubin and Derek Haswell, Zeo's social-media coordinator, sit on black leather couches in the middle of the office swapping last night's sleep scores. Haswell proudly announces he got a 93—above average for people in their 20s—but Rubin reports an impressive 105. Zeo's employees also have their sleep scores listed on their business cards.

Zeo is part of a new trend in self-monitoring, in which people use smart-phone apps and wireless, wearable devices to track and share various personal metrics with the goal of living healthier, more productive lives.

While self-tracking is, by its very definition, focused on the individual, self-trackers are often driven by a compulsion to share. The growing popularity of the movement is intimately intertwined with the social-networking boom. Runners, for example, can track runs on their smart phones using the GPS-enabled RunKeeper app, which can be paired with Zeo, the fitbit (a thumb-sized device that monitors activity), and a bluetooth Polar heart rate monitor, and then post the results to facebook.

The Quantified Self, an international group of self-trackers, organizes local gatherings through Meet-up, on online service to create and manage social events covering everything from dog-walking to wine-tasting to investing. Rubin and other members of Zeo's team don't just track sleep; those who use the Fitbit have an internal competition on the device's site, which allows groups to compare scores on steps and activity levels.

A number of startups are now forming around the intersection of self-tracking, social networks, and gaming, in an effort to keep users engaged and motivated enough to meet their goals.

"Everyone is excited about being able to automatically capture data, but that will not change behavior on its own," says David Rose, an entrepreneur who developed the "ambient orb," an illuminated glass ball that flashes light in patterns based on trends in pollen levels, blood sugar, or the stock market. "We need to get that data into people's lives in a way they will respond to."

At Earndit.com, users can input data from various tracking devices to earn points towards free energy bars, yogurt, and even an entry into a raffle for a free Zeo. A Wi-Fi-enabled scale from French startup Withings can be configured to automatically tweet the user's weight—the idea is that people will be more likely to stick to their diet if they know that the results will be made public. (Cedric Hutchings, Withings's founder, says not many people avail themselves of this option.) At Dailyfeats.com, users can choose from a wide variety of healthy things they want to do—eat vegetables, go to bed early—and earn coupons at local stores.

But whether these efforts will succeed where others have failed is still an open question. Research suggests that use of most wellness applications, much like dieting and other New Year's resolutions, lasts about a month. Much longer-term use is needed to sustain behavioral changes that have a real impact on health. And just like a good trainer, effective health monitoring tools need to reward users in both the short term and the long term.

"Most problems people are attacking around health are things people struggle with every day for 10 years," says Rose. "That's the design challenge: how to design something that is still relevant and motivational nine months out and 10 years out."