Why is so much easier to fall asleep on a couch unintentionally than in bed intentionally

....and why don't they make beds the same way ?

Relaxed state of mind? When I fall asleep on the couch I'm usually doing something that doesn't require much brain power, such as watching TV. I'm not thinking about all the day's stress as I am when I lay down in my bed.

Because when you choose to lay on your bed, it's usually intentionally. Duh! 🤷‍♂️

The "unintentionally" part is a major clue there, I figure.