It seems like a silly question, but it is one of the most common horse related questions. Can horses lie down?
The quick answer is Ýes, a horse can lay down.
In fact a horse must lie down every day in order to get deep sleep or rapid eye movement REM sleep. REM sleep is when a mammal enters a sleep where there is low muscle tone, random eye movement and dreams. However, horses do not need to sleep as long as humans. If not able to lie down to sleep a horse will eventually become sleep deprived leading to behavioral and mood issues and increased chances of becoming sick.
Horses have the ability to snooze or nap standing up for short periods of time throughout the day. In the wild, horses have the natural fight or flight response and remnants remain despite domestication. Sleeping standing allows them to run when attacked by a predator such as a mountain lion. A horse can lock its knee cap using tendons and ligaments to keep the joint aligned allowing for a nap whilst standing; this ability is unique to horses and called the ‘stay apparatus’.
A horse will only lay down to sleep if it feels safe or there are other horses nearby to stand watch as they are not able to get up quickly. Horses only need between 1 and 3 hours sleep on average per day including both naps and short periods of REM sleep.