Sleeping disorders in horses have been occurring more in the past ten years. They are called “narcolepsy,” which isn’t accurate because this, in humans, is a lesion within the brain stem. The same is true for cataplexy, where the sleeping is acute, with the human dropping to the ground asleep. In narcolepsy, the human slowly falls to the floor.
Horses have a stay mechanism that locks the limbs in the extended position allowing them to remain standing while dozing. The hindlimb locking mechanism is understood , but the front limb locking mechanism remains a mystery. Affected horses will slowly rock backward before collapsing on their front fetlocks and knees. Callouses form from hitting the ground. If they can, such as in a stall, the horse will rock backward and brace their rump against a wall which prevents them from falling.
In 1980, when I was in vet school, a paragraph described this rare condition of war horses who remained ready for action. They remained standing in their saddles throughout the night. The thought was they never received the REM (rapid eye movement) deep sleep. However, research today suggests that this is not the case as horses who are allowed to lay down whenever they want to suffer from this sleep disorder.
It is still a mystery. I had hope when a client switched her 30-year-old horse over to the no-grain diet plus soybean meal for a high-quality protein source. She reported that the sleep disorder her horse had was no longer occurring. However, a year later, she said that it was occurring again. I also observed that the 32-year-old horse was very thin and lacked muscle which happens in 30+-year-old horses; they never fully regain their lost protein. So I would be interested in any horse suffering from sleep disorder to try removing the inflammatory food and adding high-quality protein in sufficient amounts to restore neurotransmitter function. Why not? After all, sleep disorder of horses is like so many other afflictions of horses, rare in 1980 and now becoming more common. I’m always looking for the root cause…