FaceTime burnt display

So me and my girlfriend are long distance and we both feel safe falling asleep on the phone but lately I’ve noticed after a while the end call button, mute, camera, etc. are almost burned into my phone screen, they go away after a few minutes or so but I’m not sure if one day it’s going to just stay there. Is it possible to “burn” the display. Like how older tvs can have displays burnt into them? I hope someone understands me lol I sound crazy and I wish I could show what I’m talking about but I can’t.