Thank you for your interest in the Galaxy Watch Ultra, Angel. The Watch Ultra is equipped with a sensor that detects when you start and stop your sleep cycle, tracking four stages of sleep: light sleep, deep sleep, rapid eye movement (REM), and awake time. Additionally, the watch can measure blood oxygen levels (SpO2) and skin temperature. The Galaxy Watch Ultra is compatible with phones that run Android 10.0 or higher and have at least 2.0 GB of RAM. To utilize the Galaxy AI features for data tracking, you’ll need a compatible Samsung Galaxy phone, the Samsung Health app, and a Samsung account. For any further questions, be sure to reach out to us at Support. -Kelvin