Virtually all of us dream. Sometimes we are even able to remember our dreams vividly the next morning. Everyone who owns a dog will have observed their pet 'chasing rabbits' in their sleep. But do horses dream? Before we can answer this question with any degree of certainty we need to understand the mechanics of a horse's sleep patterns.
Research has shown that there are four observable stages of a horse's sleep patterns which make up his waking/sleeping cycle and each of these stages has its own specific function.
Wakefulness: During this stage the horse is fully conscious. Most of this period is spent engaged in the serious business of eating or, in the case of wild horses, moving from place to place in search of fresh pasture. For youngsters or domestic horses kept in groups this is also the time for play and socialising and part of this stage may also be spent employed in some sort of interaction with man.
Drowsiness (DR): This is the stage in which domestic horses spend most of their time. The stabled horse is unable to wander freely foraging for food so his day is passed by dozing. Every horse owner is familiar with the drowsing horse stance; head and neck drooping below wither height, eyes closed, ears laid back along his neck and often standing resting a hind leg. In this position the horse's knees and stifles will 'lock' negating the need for muscle exertion to enable him to remain standing as he dozes.
Slow Wave Sleep (SWS): This phase is named after the electroencephalographm (EEG) patterns observed in the horse's brain during true sleep. During SWS the brain waves are slow and regular. This indicates that the brain is not functioning at an active level and the horse can thus be deemed to have entered the first true phase of sleep. As in DR, the horse utilises its 'stay' apparatus to enable it to remain standing as it sleeps. The horse must go through SWS in order to reach the deeper REM phase of sleep.
Rapid Eye Movement Sleep (REM): As the horse slips into REM he will have to lie down and will generally rest by balancing on his sternum with his legs tucked beneath him. If the horse has sufficient space to do so he will often lie completely flat out at this stage of sleep.
REM is also referred to as 'paradoxical sleep' as EEG patterns suggest that the horse's brain is almost as active during REM as it is during the waking stage, although in fact REM is a deeper sleep than SWS. The horse's body is completely relaxed, his respiration rate drops and his heart rate increases during REM. This is the most important stage in the horse's sleep pattern and is partly responsible for both his mental and physical wellbeing. It is during this sleep phase that we can observe the involuntary twitches of the eyes, muzzle and limbs.
Studies show that domestic horses generally spend a large part of their day dozing. Approximately two hours is spent in SWS over four to five sleep periods. Periods of waking or REM sleep occur randomly in between. The adult horse spends approximately 45 minutes in actual REM sleep occurring in nine periods of five minutes each. During the waking/sleeping cycle, the stabled horse is observed moving around his box, dozing, eating and periodically lying down to sleep.
So, to return to my original question: do horses dream or 'talk' in their sleep? Most horse owners would say that they do. I remember watching in amused fascination as my four year old gelding lay flat out on his bed, legs and tail twitching as he slept. He then began to whicker softly and I could see his eyelids flickering as he apparently dreamed. On another occasion I observed a friend's horse paddling his legs, whickering and whinnying quite loudly as he slept. These periods of activity only lasted a couple of minutes.
In human beings, dreams can occur in all stages of sleep although most are experienced during REM sleep. It would therefore appear that horses do indeed dream like we do. But what do they dream about?
Sleep studies on humans reveal that dreams occurring during the DR and SWS stages of sleep are usually linked directly to actual events taking place in the current life of the dreamer. Dreams experienced during REM sleep however seem to be more random and fantastical and are rarely connected to the dreamer's actual life.
Human beings rarely dream of their future or destiny so it is unlikely that your horse is dreaming of the day when he wins an Olympic gold medal! Researchers' best guess is that a horse's dreams are most likely to relate directly to his real life experiences and to familiar environments and day to day events recorded in his memory.
Unfortunately, until such time as scientists are able to converse in fluent 'equine', we can only speculate as to where our horses go to when they dream!
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