Relaxation Turning into Tension

I just tried putting my body to sleep and reaching SP 3 times in the past 2 days.
I have an issue though. It seems as though after a long enough time, after the twitching for a few minutes, it becomes very difficult to maintain a state of relaxation. By this I mean that my eyes keep trying to pry themselves open and I end up tensing my face muscles, squinting, to keep them shut. I also had trouble breathing. My breath never reached a minimal level, but instead it seems like it started to require lot more effort to keep breathing. My nose is a little blocked up, but right now i can tell it isn't enough to feel like I'm suffocating. Breathing through my mouth also seemed to take a lot of work, and just dries out my throat.
I have been doing this without any previous sleep, but I've heard that WILDs are possible without hours of sleep prior, just a lot more difficult.