Can you sleep standing up?

Can you sleep standing up?

Chris Idzikowski (Director of the Edinburgh Sleep Centre) gives expert video advice on: Does counting sheep really send you to sleep?; Can you sleep standing up?; Can you sleep with your eyes open? and more...

Now I don't know for sure. There are certainly stories about soldiers being able to march while they're asleep, so I'd tend to think along the lines that there could be situations where one's so sleep deprived that one can actually end up sleeping in that kind of state. But my initial reaction is probably not; it's more of a maybe.