Track your every calorie and footstep

"Body hackers" use the latest tech tools to customize themselves. These four companies are building businesses around the idea of tracking everything from your sleeping patterns to your heartbeat.

Lark
Founded: 2010
Tracks: Sleeping habits

With a bit of hardware, your iPhone can become your personal sleep coach.

Users wear Lark's lightweight wristband throughout the night. It gathers intel on how long it takes you to fall asleep, how many times you wake up, and other details about how soundly you're sleeping. The data is sent to Lark's iPhone app for your perusal. The wristband also serves as a silent alarm clock.

To develop the technology behind the service, Lark founder Julia Hu worked with a Harvard sleep expert and a professional sleep coach who helps NBA and Olympic athletes optimize their rest. The wristband and sleep tracker sells for $130. An extra $60 gets you the Lark Pro package, which includes a "Sleep Coach" app.

Lark's initial pitch met with heavy skepticism. "I just have a hard time believing you're serious," Napster co-founder Sean Parker, now an investor in tech companies, told Hu in response to the company's launch presentation at a TechCrunch conference in September.

But Hu got the last laugh. She landed a major champion: Apple. The company loved Lark and is now its exclusive retailer, selling the system in its stores and through its website.

Lark has raised $1 million from angel investors and is in the process of raising its first major funding round.

By Laurie Segall - Last updated August 03 2011: 4:25 PM ET
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