Can the Oura Ring function when my phone is turned off?

Yes, the Oura Ring can function when your phone is turned off because it is designed to collect data independently with its built-in sensors and internal storage. Once you turn your phone back on and open the Oura app, the ring will sync its stored data with the app. The ring typically has enough internal memory to store several weeks of data, so you do not need to have your phone on and nearby at all times for the Oura Ring to continue monitoring your activity, sleep, and various physiological metrics. However, you won't be able to view updates or receive real-time feedback until you sync the ring with your phone's app once again.