The Lark isn't the first wearable device to track one's sleep patterns, but the system adds a clever coaching element that other sleep trackers don't include. It's an important addition, as competing devices tend to smother the user in sleep data, but don't provide many tools to make sense of the data in an actionable way.
Source: http://www.wired.com/gadgetlab/2012/01/lark-julia-hu-sleep/
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