Too many bear stories to list after 13 years in Alaska including several summers in the bush. The one that will wake me up at night 40 years later happened on the Western side of the Alaska Peninsula about 150 miles south of King Salmon on a fine September day out caribou hunting.
Waiting for a herd to move through, I laid down in the moss under a low shrub, there are no trees there, this was the best concealment available, and promptly fell asleep in the sun. Woke up with a very cold feeling and a little voice in the head saying "DO NOT MOVE". Rolled my eyes around and there laying under the bush about 10' to the left was a very large brown bear doing the same thing, caribou hunting. The Brown is considerably larger than a Grizzly due to their diet.
What do you do? I might have been able to shoot the bear, but he would easily (and probably) have killed me before he dropped. This seemed a poor choice at the time.
I could get up and run like hell, knowing this guy could run faster than a thoroughbred race horse. The bear would catch me and eat me. This also seemed a very questionable life choice.
I could lay perfectly still, try to control my breathing and hope the bear would go away. This at the time seem to be the very best bad choice available, and that was the plan followed. The plan actually worked because I am writing this, and am not bear scat turned to fertilizer on the Alaskan Peninsula. After what felt like three days, or maybe it was 20 minutes, an obliging herd of caribou appeared and the bear had a nice fresh cow for dinner. I left in the other direction back to camp, changed my shorts, and drank myself into oblivion.
Got my caribou the next day, but did not fall asleep under a bush again. Lessons learned; brown bears are much scarier without bars separating them from you, and appear much larger up close. They don't smell very good either.