ASK YOUR SCIENCE TEACHER by Larry Scheckel
This week’s question was asked by:
Do horses sleep standing up?
This question was a source of endless argument for the three Scheckel brothers growing up on that Crawford County farm outside of Seneca. We never did come to any definitive conclusion. We even snuck out of the house one summer night and went to the barn where Dolly, Prince, and Lightning were standing in their stalls. We couldn’t figure out if they were sleeping or not sleeping.
Therefore, I finally got this answer straight from the veterinarian’s mouth. Dr. Steven Doll is an expert on horses. Dr. Doll says that horses have a suspensory ligament apparatus in the lower leg that locks up. Their legs can lock in place, enabling them to fall asleep without falling over. So, it turns out that horses do sleep standing up and horses also sleep lying down.
Historically, horses were prey for wildcats, lynx, and mountain lions, and did not feel safe sleeping on the ground. Most of their sleeping was done during the day rather than at night, when predators were out hunting. Horses have straight backs, so they cannot get up quickly. If an enemy mountain lion were to come along while on the ground, the horse might not be able to get up fast enough to make an escape.
In the wild, horses only lie down in a herd and a select few will opt to remain upright. It is their defense designed to protect the herd from predators. Horses are at their “weak” moment and are vulnerable to attack.
When the horse is standing still, it is able to relax such that there is little fatigue. Except for a few minutes each day when it is in deep sleep, the horse can remain upright. If necessary, it can remain upright for several days before it lies down. It can “rest” in the upright position because of the ‘stay mechanism” of the forelegs and hind legs. The joints are locked in position by a system of muscles and ligaments.
Horses are not able to lie down for long periods of time. Rib cages only allow so much pressure for any amount of time. Average lying-down time for a horse is about 30 minutes.
Horses do occasionally take short naps lying down during the day. This helps them to rest their legs. You can sometimes find a horse stretched out on its side, asleep in the sun, or lying on the ground with its legs folded under.
A ligament is a strong flexible connective tissue that joins bone to bone. They are parallel bundles of collagen fibers. We humans have something akin to the horse. We humans have a suspensory ligament that holds the lens in the correct place in our eye.
Dr. Doll warns that a sleeping horse should not be disturbed. A startled horse may kick.