I found my gelding, a couple weeks after I bought him, flat out on his side, his legs were twitching and he was making odd noises (exactly like a dreaming dog). I went running in there screaming and he opened one eye, gave me a death stare, got up and grumpily stomped off. I apparently interrupted a good dream! Oops!
It's not unusual on a warm, sunny day after the weather has been horrid to go out and find all the horses at the barn completely flat out and sound asleep. They make a poor 32+ pony, who hardly ever lies down, guard them!