DEAR DR. WELDY’S: “I like to watch my horses through my kitchen window while doing dishes. I often see them standing motionless or sometimes lying down on their side, which made me wonder, do horses sleep?”
DEAR READER: Horses do need to sleep, but in a far different way than we as humans need to sleep. Horses average only two and a half to five hours of sleep every 24 hours. Many horses can average on the low end of this for weeks or months. Most of this is done in multiple short time periods, about 15 minutes at a time.
Additionally, horses can go weeks without a full sleep cycle. They are neither diurnal nor nocturnal, but amass most of their sleep time during the night with intermittent periods of alternating rest and sleep during the day, especially when confined to a stall. Certain relaxing situations, such as grooming or standing quietly in crossties, can lead to episodes of sleep in normal horses.
There are four phases of sleep in horses: diffuse drowsiness, intermediary, slow-wave, and paradoxical.
Diffuse drowsiness occurs when your horse is standing square with one hind leg cocked or relaxed. They often have their neck and head slightly lowered and relaxed eyelids, ears and lower lip.
The intermediary sleep phase involves your horse checking out its environment, perhaps looking behind, and then lying down if all feels safe. Once down, he will enter diffuse drowsiness again and then possibly slow wave sleep. When lying down, drowsiness is generally characterized by lying on their chest with feet tucked underneath.
Slow wave sleep is generally entered while lying flat on their side. Paradoxical sleep can be accomplished in either lying position and constitutes about 15 percent of the total sleep cycle. It is here that REM sleep occurs. Recumbent REM sleep in the horse can be dramatic, including leg paddling, muscle twitching, ear movements and nostril flares.
Much research is yet to be conducted concerning horses and their sleep patterns. For now we know that horses do need sleep and that both environmental and physical factors can influence how much sleep a horse gets. The more comfortable and safe they feel, the more sleep they tend to experience. The amount of sleep required varies from horse to horse, just as it does for us.
Questions for Ask a Vet can be asked either by e-mail to firstname.lastname@example.org, by regular mail to Dr. Weldy’s Associates, 114 N. Elkhart, P.O. Box 527, Wakarusa, IN 46573, or by visiting the web site at drweldys.com.