they don't sleep standing up. Only horses do. Cows can "dose off" standing up, but they have the herd instinct thing to protect each other and they wake each other up if danger is premenent. Living in rural nebraska, it's amazing that even most people here think you can do it. One of my friends bet some guys 50 bucks they couldn't tip a cow. They had to video tape it too. They tried several times and never even touched a cow because they never found one sleeping standing up (big surprise) and they all ran away when they got near.