You can doze, whilst standing ,
but should you really fall asleep, you would fall down ,
LoL!
and wake yourself up .!!
Unless of course ,you were propped up by two good friends ;
on your way back home ,after a good night out---- LOL
you may be 'sleep walking !'
Usually ,
you will have already, been asleep in bed ,
before you get up --to sleep walk --
you may even walk back to bed , whilst still asleep
>^,,^<