I was really starting to feel the buildup of exercise in the space between my shoulder blades. While doing a partner exercise in wheel pose, it felt like something was going to snap in my back - not a feeling I liked! It's a heavy pressure, very uncomfortable, borderline on painful depending on the force being applied. So when my partner used the belt to draw my hips away from my shoulders, it was not a good thing for me.
All in all though, I felt like practice was exhilarating, minus that one pose of course! They say back bends should typically be avoided at night because they compress your adrenal glands and cause an increase in adrenaline that will keep you up. But for me, they are such hard work that I find them energizing at first, and then I'm just wiped out. I slept heavy that night, so I guess exertion won the battle against adrenaline.