I set my BR-9C RF meter to click when RF is detected, and put it next to me while i went to sleep. I put my phone in airplane mode, and had my laptop record the meter clicking.

Here is the video that contains the audio in which you can clearly hear the clicks increasing dramatically, until it is a buzzing sound, while I fall asleep. The buzzing abruptly stops when you can hear I am waking up. You can deduce when I fall asleep and when I wake up based on the breathing sounds.