The Jawbone UP electronic bracelet measures the wearer's daily activity and nocturnal sleep patterns. If you are bored by the official smartphone app, you can create your own Perl scripts and access your data via the unofficial web API.
To counter the widespread tendency to excessive body fat, many smartphone owners now carry little gadgets around with them, reminding them of their lack of physical activity during the day. If you sit motionless for hours in front of the screen, the idea is that such a device could motivate you to walk around the block more often, or at least use the upstairs bathroom. This trend toward self-measurement – known as quantifying yourself – has grown very popular lately.
An electronic bracelet like the UP  by Jawbone measures the steps you take and shows the distance traveled and calories burned in the associated smartphone app (Figure 1). The accessory is available in three sizes and several colors and costs about US$ 130. From a functional point of view, the device seems to capture only instantaneous acceleration values and accumulates them over time. The geographical position of the wearer could be determined with a GPS chip, but this added function would probably drain the device's small battery in next to no time.
Figure 1: The Jawbone UP bracelet tallies its wearer's physical activity during the day by tracking acceleration.
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