Anker's New Sleep Earbuds Track Your Body and Play Soothing Sounds to Help You Doze Off

Anker's Soundcore Sleep Earbuds 4 Pro, arriving in November at $349.99, use a small light-based sensor inside the ear to read heart rate, stress, and fatigue. That data feeds BioSync, which adjusts calming audio to help you fall asleep — going beyond simple background noise. The standard model ($229.99, October) skips the sensor.