That falling asleep whilst watching a movie or show lying down is a perfectly normal thing to do and shouldn't be frowned upon.
I enjoy watching movies and TV shows. Sometimes when I am feeling incredibly relaxed I watch them in a horizontal position. Sometimes after about thirty minutes a deliciously sleepy feeling passes up my spinal cord. This electrical charge starts to weigh heavy on my eyelids. Stifling a yawn I will stealthily start to close my eyes with rapidly increasing frequency. If I am careful enough I will drop into a deep coma and wake up directly as the movie finishes.
I say careful enough because I am often poked, prodded and belittled for falling asleep. I also have an annoying habit of being angry when woken from such states. I like to think of this as the Dragon effect. Dragons are bad tempered brutes especially when aroused from sleep. I am incredibly defensive in such states and say anything to protect my sloom.
"I am still awake"
"Why are you hitting me?"
"Leave me alone can't you see I am busy watching the movie?"
Naturally I am not a very popular person after these slips into slumber. Of course if the movie or tv show was really riveting I would not fall asleep. In fact I can safely say I have never not watched something that was really worth watching.
A Dragons lament. Maybe I could watch things sitting up? but I can't see any fun in that......