I have similar numbers to you on stage percentages. I am concerned with too little deep sleep. My average is 6%, with light 78%, REM 13%. I questioned the accuracy of my Apple Watch but then I was turned on to this video on You tube. Search for The Qualified Scientist and the video “Apple Watch : Scientific Sleep Test”. His research yields watch accuracy ~80%.

I take Lunesta for sleep which unlike Ambien allows REM. It works just ok and doesn’t keep me asleep all night. Still struggling with getting enough sleep since I was a child.