Do I lay down on an empty train/bus? No because its in public and people would stare.
Do I lay down in the office? No, because that's considered unprofessional.
Do I always lay down at home? Abso-fracking-lutely!
Do I lay back in my chair in front or the TV or while using my laptop? Well, I usually lay on the floor, not in a chair, but yes.
Laying down is the only position I find truly comfortable, and I generally do lay down either in bed or on the floor as much as possible except when eating (as that gets too messy).
Furniture is for guests.