Regardless, the Basis approach to sleep analysis trumps that of any other activity-tracking system I've used. And perhaps best of all, sleep tracking works automatically: You don't have to push any buttons on the wrist band to begin or end sleep logging.
Now I can't testify to the incontrovertible accuracy of Basis' sleep data, but it does jibe with my own anecdotal observations (at least in terms of when my sleep begins and ends), and more or less runs consistent with data I've pulled from the Jawbone UP24. Interestingly, when I compare the UP24's sleep graphs to Basis' sleep graphs, it looks like Jawbone recognizes my periods of REM sleep as deep sleep.
But this could change if Jawbone ever implements the technology it received when it purchased BodyMedia. Indeed, a heart rate sensor should be somewhere in Jawbone's future, and this could help them crack the REM puzzle as well.
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