Sleep is an important part of our health and is equally as important to our horses’ health. Lack of sleep or a sleep disorder may impact a horse’s physical activity, attitude and quality of health and life. Horses actually require very little sleep compared to people. The average horse spends as much as 3 or 4 hours per day actually sleeping, with another 2-3 hours per day in a drowsiness state. Even though horses can sleep standing, they need to be able to lie down and rest at least some of the time. Only about 30 minutes per day is spent in the REM sleep. The domestic horse that is confined to a stall and is on a feeding and exercise schedule is forced to time his sleep cycle at night, adapting his periods of rest to the human schedule.

There are four stages that make up the sleeping and waking cycle of the horse, that are observable:
- Wakefulness Stage is when the horse is fully conscious and aware of what is going on around him. During this “wakefulness” horses can be consuming food, running or playing in pastures with other horses or being ridden or enjoyed by man.
- Drowsiness stage (DR) is probably the stage in which most domestic horses spend most of their time. Horses in confinement, unable to freely find their own food, have to wait for the scheduled feedings and exercise that humans provide for them. In this situation a horse may drowse away the day. During this drowsiness stage the horse is relaxed with head and neck slightly drooping below wither height, eyes closed, ears gently back, and standing with supporting weight on three legs with one hind leg cocked. While in this stage, the horse relies on the stay apparatus in their legs. The ability to lock his knees and stifles allows the horse to remain standing during this stage of rest.
- The Slow Wave Sleep (SWS) is identified by the reduced electroencephalograph (EEG) patterns in the brain which has been used to aid in distinguishing true sleep from waking. During the slow wave sleep, the EEG monitored brain waves are slow and regular, indicating that the brain is not functioning at its most active level and is said to be the stage the mind sleeps. It is believed that SWS is the first stage of sleep that a horse goes through before reaching the rapid eye movement sleep (REM). Horses that are in SWS are able to use the stay apparatus in their legs to remain standing, but they will have to lie down before going into REM sleep.
- Rapid Eye Movement Sleep (REM) has been called the paradoxical sleep showing similarities in brain waves to that of waking. EEG patterns indicate that the mind is almost as active as waking, even though REM is a deeper sleep than SWS. REM is the most important stage in sleep, but not fully understood. The heartbeat rises slightly while respiration rates declines during REM sleep. REM is partly responsible for both the mental and physical well being in all animals.
Sleep disorders occur in horses and can cause serious problems. The most common disorder is sleep deprivation. Many things can cause sleep deprivation, such as environmental stresses, issues with herd dynamics, pain related problems, late-stage pregnancy that hinders ease of lying down, traveling and competition, and hospitalization.The horse may show signs of excessive sleepiness with sudden loss of muscle tone triggered by strong emotions.
Narcolepsy is different than sleep deprivation. According to equine neurologist Steven Reed, DVM, ACVIM, “narcolepsy can be defined as a rare and incurable sleep disorder of the central nervous system characterized by uncontrolled episodes of loss of muscle tone (cataplexy) and sleep. Any horse that appears drowsy, weak or collapses should be examined by a veterinarian for an accurate diagnosis since this type of medical condition can be dangerous to both the horse and his handler.”
Readers are cautioned to seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy. This newsletter is intended for informational use only and does not express the views or opinions of C. Jarvis Insurance Agency.
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Newsletter is written by Margie Turner. Information and material was obtained through the following: www.mirrorkbranch.com, Hitting the Hay; www.thehorse.com; www.ezinearticles.com How Horses Sleep and How it Affects Their Behavior;www.smartpakequine.com – Sleep Deprivation & Narcolepsy.