What defines the shift from Early Digital monitoring to standard Wearables?

Shifting the tracking mechanism from the bedside to the body.

The technological progression in sleep monitoring involved distinct stages regarding device placement. Early digital methods, exemplified by applications like Sleep Cycle, often relied on ambient monitoring where the phone rested near or on the mattress, interpreting vibrations. The significant shift that defined the widespread adoption of standard wearables was the physical relocation of the sensor system from stationary bedside placement to direct attachment to the user's body—typically via wristbands or rings. This move allowed for direct measurement of body kinetics via accelerometers and integration of optical heart rate monitoring (PPG) directly from the skin.