My favorite of the three, the Up 24 blends function and style. Beyond being the most fashionable of the trackers I tried, it was the most full-featured and had the most user-friendly app. The single button on one end of the band shows you how much power the device has and lets it start or stop tracking your sleep. One of its best features is its "smart alarm," which wakes you with gentle vibration when you're in a state of light sleep, up to 30 minutes before your planned wakeup time.
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