I agree,
With the body in a 'tense' mode constantly. I also have a tremor, since my tbi, and that is really what brought the tiredness to bear. If you think of your muscles in spasm, or tremor, that must take tremendous effort. I find that a cup of tea, and a valium, (seems odd) give me a decent days worth of energy. I think the valium 5mg, helps with the tremor, and spasm. I use a CPap also, and I hate it.
I also tried that 'Provigal', which just cranked my pain up.
Along with the spasms and tremor. I thought it was Satan's own drug!

Hope you get some relief!

Pete
asb