Horse

Its answer is unknown . lets see about the view of others.

Ok isha just wait for others to answer it is simple easy way.It will tell us one
new thing.

share in some more details. it seems it will take time for others to answer this. so just let the details be shared.

Horses can sleep standing up, as their legs have a specialised locking mechanism which means they don't fall over.

http://wiki.answers.com/Q/Do_horses_sit_down_or_lay_down_at_all

A draft horse sleeping while standing up. Horses are able to sleep both standing up and lying down

Vaishnavi got the correct answer.Horses have strong legs they will sleep by standing only.

Sasikanth , horse even sit on its knee and sleep also. and even by standing also

Sarala horse will sleep maximum in its life time by standing only it will sit rarely.

yes, sasikanth you are right. horse sleep by standing and some time it sit and sleep.I think by standing for long time it wont get pain ?