Bluetooth technology has been around for over 20 years & it uses low-power radio waves that are classified as non-ionising EMR. Or, in normal English: These waves are safe for humans as they emit super low-level frequencies (much lower than cell phones or WiFi routers) These waves are very safe and cannot cause any harm whatsoever. In saying this, our sleep mask turns off automatically after 30 minutes of silence to save battery and improve your sleep. You can also set a timer for 1 or 2 hours to turn it off automatically when you don't need it anymore.