Sleeping Patterns
by: Sue McDonnell, PhD,
Certified AAB
I
think my 11-year-old mare isn't getting enough sleep. My mother and I have
seen her start to fall asleep in her paddock and in her stall
during the day. Her eyes begin to close, her lower lip hangs loose,
and her head slowly lowers. When it gets down near her chest, she violently
flings it up to wake herself. Sometimes she won't catch herself in
time and her legs buckle. It's a scary thing to watch and makes me
sad. When I ride her, she's very lethargic. She was alone for almost
a year, then we got a goat to keep her company, thinking she might
feel safer and sleep more. But nothing has changed.
We close her in her stall at night, but she can't see the goat in the
next stall over. Would it be better if she was able to see the goat at
night? Her door in front is a half door, and there are Dutch doors in back
that open up into her paddock. Would it be better to leave her back doors
open at night so she doesn't feel confined? I also have a hard time getting
her in at night. She likes--or feels the need--to look out towards our
neighbor's yard. She does not look alert when she's out there at night.
She stands with a hind foot cocked and appears to be staring into space.
Is she standing guard, or does she just like to be outside? What should
I do so that she'll sleep more?
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Your letter brings up a lot of great questions, so I'll
take them one at a time. First, let's talk about horses' normal activity
and sleep pattern.
Horses are neither diurnal (day-active) like people nor nocturnal (night-active)
like cats or raccoons. Rather, they have alternating periods of active
foraging and rest that go around the clock. The length of the foraging
and rest periods vary and seem to make sense in terms of the weather and
other various conditions. So for example, in summer there are longer rest
periods in the hot afternoons, and foraging periods tend to be longer in
the coolest part of the day, usually just before dawn. The length of the
active and rest periods are also affected seasonally and daily by other
environmental conditions, such as weather, bugs, available forage, water,
and other factors. Other species with this type of pattern are some primates,
such as some of the lemurs. Biologists use the term "cathemeral" to
describe species like horses that are neither nocturnal nor diurnal in
their activity and sleep patterns.
Horses living in various domestic conditions maintain this pattern more
or less. Of course, there are obvious effects of people's diurnal pattern
and our practice of feeding them on a human meal schedule. But when living
at pasture or when they are not working or otherwise directed by people,
horses exhibit alternating periods of fully alert foraging and periods
of rest around the clock, night and day, just as wild horses do. Each rest
or foraging period lasts anywhere from one to three hours. So, your mare
looking sleepy and falling asleep during the day is normal behavior for
a horse.
But let's next discuss your concern about her apparent exhaustion. From
what you describe, as you suspect, there is likely something abnormal about
the character of Jezebelle's sleep. It sounds like maybe she is going into
such a deep standing sleep that her legs buckle, then she suddenly awakes
and her head pops up fast to catch her balance. It's hard for me to judge
without actually seeing it, but she might have something wrong with her
ability to remain standing during normal standing sleep. Perhaps you can
take a video of her when she is doing this. Get a few examples and sit
down with your veterinarian, who can help you figure out what is going
on. If you don't have a regular equine veterinarian where you are, you
can send them to me and I can work with veterinarians here at the university
and get back to you with our opinions.
There are some unusual conditions that, while rare, do occur in horses.
One is called narcolepsy, a condition of the brain characterized by falling
asleep over and over, in situations where the animal would be expected
to be alert. So, if your mare is falling asleep when you are feeding her,
for example, or when you are getting her ready to ride, or when she is
startled, then she should be evaluated for narcolepsy.
As you and your mom were thinking, simple sleep deprivation can lead to
a state of exhaustion and behavior like you are seeing in your mare. Horses
can sleep standing up, but they do need to lie down eventually and go into
a deeper sleep than they can do standing. Otherwise, they start to go into
the very deep sleep while standing and buckle at the knees. As you suggest,
maybe because your mare is the only horse, she is always having to remain
vigilant to potential threats. That is normal behavior when a horse is
in a new, especially busy, and/or threatening environment.
But most horses eventually acclimate to their environment and lay down
for naps throughout the day and night at the quietest times. If you and
your veterinarian expect that this is the case, having the goat or a horse
companion to share the sentinel work would likely help. And to answer your
specific question about being able to see the goat, I can say that for
most horses, that would be better. Being together in one stall would be
even better than in separate stalls. And yes, opening up the top of the
Dutch door and any windows can sometimes help as well.
Also, if you can make a run-in arrangement in which she can go in and
out of the stall on her own, or just leave her out in her pasture at night,
she might feel safer than in a closed stall. That's because while we might
feel safer in a closed area, horses seem to feel safest when some can escape
in a hurry, and they are more likely to lie down when out in the open rather
than in a stall where they can be cornered. When your mare is standing
out there with one leg cocked and seemingly staring into space, that is
a normal standing rest for a horse--resting, but pointing in the direction
of the most likely threat and ready to escape if needed. So with what you've
told me, I'd guess she is comfortable in her pasture.
Some horses with serious physical impairments appear reluctant to lie
down. It's usually in older animals, but can also be the case for a young
animal like your mare. Sometimes the trouble appears to be just difficulty
getting down, and sometimes it is just with getting up. With time they
appear to reach a point of exhaustion. Some of these horses have much more
trouble in a stall than out in the open, particularly if the footing is
slippery in the stall. Be sure to describe the sluggishness on the trail
to your veterinarian so she can try to figure out why that might be. For
example, maybe something painful is the root cause for both the sleep problem
and the sluggishness.
Your questions about your mare getting enough sleep at night reflect thoughtful
concern for her welfare. Without knowing all the ins and outs of normal
animal behavior in the natural environment and how that translates to domestic
conditions, it is quite common to understand behavior in terms of human
behavior and needs. We naturally think that our horses should feel safer
in the barn at night and should sleep at night. This tendency of humans
to interpret animal behavior as if they were people and to attribute human
characteristics, emotions, and thought to animals also has a catchy scientific
name--anthropomorphism. It's something that trained animal behaviorists
and welfare specialists work to avoid, because it is easy to make mistakes
in animal welfare by assuming they like and need what we do. But it's not
a bad place to start.
