If you're like most people, you need a good, solid eight hours of unbroken rest every night. If you don't get it, you drag through the following day dull, drowsy, and sleep-deprived. You might assume that your horse has similar needs. But according to Sue McDonnell, horses do well with far less sleep than people.
Horses typically spend anywhere from four to fifteen hours a day in standing rest, and anywhere from minutes to several hours lying down. Only part of that is actual sleep time, taken in brief naps that last a few minutes each. The daily total sleep time for an adult horse may range from a few minutes to a couple of hours. Foals and young horses, like other youngsters, sleep more, more deeply, and more often than adults.
This pattern is another plus for a prey animal: His sleep can be interrupted repeatedly by predators and false alarms, but he'll still function. Rarely does a horse suffer from true sleep deprivation, says Sue McDonnell. The minimum amount of deep (lying-down) sleep he needs is very small--perhaps an hour in many days. Still, if he doesn't get that minimum, he eventually begins to drift off into what appears to be deep sleep while standing-and buckles at the knees.
Where you want your rest in a solid block of time, horses spread theirs out in scattered periods throughout the day and night. According to Sue McDonnell, "For any horse or group of horses, there is usually a recurrent pattern of rest and other activities," such as grazing. The pattern varies with the weather, the season and what's going on around the horse. Stabled horses, affected by the activity around them, typically get much of their sleep during the evening and early morning hours.
"Horses tend to learn the pattern of the barn," Sue McDonnell says, "and their deepest rest and sleep tend to occur soon after the busy 'people day' ends."
You're probably not surprised to hear that horses sleep best when they feel safe from danger. But the factors that help them feel safe may not be what you think. When you put your horse in his stall and close the door, you know he's protected. But he likely feels isolated and confined-and for a horse, isolation and confinement can be dangerous.
As part of her work at U of P, Sue McDonnell has studied the behavior of a semi-wild herd of ponies over time. She says feral horses actually sleep more than stabled horses. They also get more down time: As members of a herd, they're able to relax because one horse acts as a sentinel, standing guard while the rest snooze. "In feral groups, all individuals tend to rest together, eat together, go to water together. The young may get additional rest and sleep during grazing, with the protection of the adults." The adults share the sentinel duty, so everybody gets to lie down.
Solitary adult horses tend to get less deep sleep than horses in groups--probably because, with no sentinel on guard duty, and no other horses to help deal with danger, the solo horse feels he has to look out for himself at all times. He startles out of sleep at the slightest disturbance. In many cases you'll see horses stabled next to each other rest standing against the two sides of their shared stall wall, Sue McDonnell says--probably to take advantage of the sentinel effect.
See also: How Horses Sleep
This article first appeared in the September 2000 issue of Practical Horseman.