Does My Horse Have Narcolepsy or Sleep Deprivation?

Horses that seem to fall asleep on cross-ties or while standing in the stall might make you think they have narcolepsy or sleep deprivation.

The definition of narcolepsy is a neurological sleep disorder that is characterized by daytime sleepiness and loss of muscle tone that leads to sudden and brief collapse. This is very rare in horses, but it is often misdiagnosed due to the clinic presentation of collapse. What is more common is sleep deprivation.

Normal Horse Sleep

Horses have multiple short sleep periods throughout the day and night, with most of their sleep occurring at night.

Horses need approximately 5-7 hours of sleep in a 24-hour period. They can sleep standing up due to a unique system of tendons and ligaments called the “stay apparatus.” However, they do need to lie down for REM sleep.

If a horse is unable to lay down, they might not get enough sleep. This can lead to drowsiness and in the most significant cases, collapse.

Sleep Deprivation

There are many causes of sleep deprivation in horses. Most often the cause is either from musculoskeletal pain or from environmental insecurity.

In older horses, musculoskeletal pain from natural aging or other causes can make it difficult for a horse to get up and down. They are unable to achieve REM sleep in a standing position, so they become so exhausted that they collapse.

They often back themselves into a corner (of a stall), slowly lower their heads, and brace their hind ends on the wall. As they fall asleep, they buckle their fetlocks and catch themselves before they hit they ground.

This is why they develop lesions on the front of the fetlocks that can be a tell-tale sign.

narcolepsy sleep deprivation front of fetlock injuries — Dr. Amy Polkes warned horse owners to be on the lookout for injuries such as these lesions on the front of
this horse’s fetlocks that might indicate sleep deprivation. *Courtesy Dr. Amy Polkes*

Environmental Issues

Insecurity in the environment is another important cause of sleep deprivation in horses. Equids are herd animals and need to have “someone” watching out for their safety. Horses that are kept individually can feel unsafe and will not lay down for REM sleep as there is no horse that is on the “lookout” for danger.

Horses are herd animals, so this is only one of many reasons they should be able to socialize and have touch interaction with other horses.

Another cause of environmental insecurity is if they sense danger. This could be a wild animal (i.e., coyote, bobcat, wolf, or other predator) in their proximity that causes them to lose sleep and leads to sleep deprivation collapse.

Final Words

If you suspect your horse is not laying down, if you notice lesions on the front of the fetlocks, or you see episodes of drowsiness or collapse, please contact your veterinarian for further evaluation of your horse. Horses need sleep! A well-rested horse is a happy horse!