I just went through 2 nights of about 2 hours sleep each - sudden onset - where all my usual stuff barely made a dent. It was nightmarish, only I wasn't sleeping enough to have nightmares! Was just wide awake, no sleep in sight. I wracked my brain trying to find if I was doing or taking something different. I noticed that the wide awake feeling was very similar to how I felt a few years ago when I was extremely sensitive to MSG in all its iterations - if I had anything related to MSG at dinner, I'd be wide awake until at least 3:00 a.m. After a few years of this I finally discovered that pantothenic acid (which I'd been taking for some years for my adrenals) depletes taurine - and taurine is necessary to help deal with neuro- or excitotoxicity in the brain!
So I immediately cut out pantothenic acid as a separate supplement (still had some in my B combo) and started taking taurine, and some time later my MSG extreme sensitivity disappeared.
So the other nights felt like my MSG reactions, but even worse. So I started researching things that could deplete taurine, and then came across something which said that taurine is made in the body from cysteine and something else. Bingo! A few weeks ago NAC became just about impossible to get due to the FDA. So I had run out of NAC but thought at the time, oh well, I didn't notice it doing anything for me anyways,
So yesterday I took 3 grams of taurine during the day in divided doses, was able to take a short nap, much to my surprise, and slept pretty well last night! It was fantastic.
NAC does seem to be readily available again, at least for now. Anyways, I highly recommend taurine for sleep. I took the 3 grams during the day yesterday but it helped with sleep at night. It didn't make me sleepy during the day either, apart from my much-needed nap.