Horse falling down / falling asleep

I've noticed this a few times in the past week. When I got to the barn this morning, my horse was nodding off and almost falling to his knees. He would wake up and catch himself each time and never actually fall, but it was scary to see. For the next few hours, we had a very successful ride, a little dressage, some jumping and a quick canter around the hay fields. He had no signs of lameness and had PLENTY of energy for his ride. After that he spent another 2 hours out on pasture grass with no problems. He came back in for his dinner and now he's doing it again. He did this for a few weeks last year and it disappeared on it's own. It's just a little scary to see. I did find a puffed up tick on him 2 weeks ago, but Lyme disease seems to produce joint stiffness which he obviously does not have from the way he's been training. He also has had hives on him in random different places on his body over the past month. It does not appear to be food related, so I'm thinking maybe he has allergies to airborne things and the allergy is knocking him out? Any ideas?

I have no clue, I don't think it would be from allergies.The bumps on him may be just bug bites,Do they go away after a couple of days? As far as him nodding off,I have no ideal.

Could be he isn't getting good sleep. Horses need to be laying down to get REM (deep) sleep. There may be something going on at night that is keeping him alert and on guard.
Both my fillies will fall asleep at the hitching rail and have actually fallen down, saddle and all


ETA- as far as the allergies, Shiloh is on Tri-hist (antihistamine) all summer and I just recently put her on a flax type supplement. It seems to help the ugly itchy's

Yeah, I just started adding Flax to his food a week ago. Already I'm seeing an improvement on his belly. He gets attacked by gnats every summer. This is the first sign I've seen of maybe getting on top of it.

I watched a 32 yr old mare do this where they fall asleep standing, her nose was on the ground and her feet were all spread apart and her butt was stuck in the corner of her stall....she kept buckling at the knees and nearly falling but she would wake up just to catch herself and start all over....was weird. I don't know the answer to what would have been happening but going to watch this post to see if anyone knows...sorry I couldnt help just thought I would share!

Lack of REM sleep is the most likely cause. Since it's seems to be seasonal, maybe there is something that goes on around your barn at this time every year? But look for some change in the activity/environment in and around the barn to try to pinpoint what is preventing your horse from laying down and getting enough deep sleep.

(For senior horses, often they get to the point where getting up and down is so painful/difficult that they stop laying down to sleep and end up being sleep deprived.)

Weird. I used to know a horse like that. Well, he only did it once. One day he was being ridden and just fell asleep. Fell wrong, and unfortunately he died. It was determined that he had narcolepsy, you should get your horse checked, no one would know much better about your horse's problem than a vet. Of course it's probably not that horrible, he might just not be sleeping well, but still. You just never know, especially with a horse.

I think its a lack of sleep. I have heard of alot of horses doing this. How long has he been at your place, or if you board?

A horse I worked with would do this alot. It was funny, but kinda scary. She made a huge mess in her stall, and so I doubt she ever layed down to sleep at night. I never saw her lay down in the paddock. So she was probably sleep deprived.

Others have mentioned REM sleep. There are good articles at the Equus website including one with videos so you can compare w/your horse.

Equine Sleep Disorder Videos

Is Your Horse Sleep Deprived?