Jerry wrote:

LOL, in the context of the OP, would it matter?! Also if someone
has only just got on and is already 'asleep in their seat' isn't
that a cause for concern anyway...

It's hard to tell at a glance if someone is sleeping or just resting their
eyes. I've often travelled at all times of the day when I've been dog tired
and will get into a rest position as soon as I sit down to conserve energy
until I get home.