I steered clear of the Acetyl-L-Carnitine because I had been taking apple cider vinegar (acetic acid) which seemed to make my insomnia worse and increased my anxiety. In fact, a little booklet titled "L-Carnitine"--which coincidentally just came in the mail yesterday--says "An equally important metabolic role is the removal of acetyl units from inside the mitochondria." This is a very interesting nutrient.
I went with the L-carnitine fumarate because fumarate is part of the Krebb's energy cycle. I need something that gives me a little more energy without making me wired. Seems to be helping, but it's only been 4 days. So many things have seemed to help for the first week, only to fizzle out or create further problems after that.
Mandolin - I saw sites that say don't take carnitine after 3 p.m.
Luella - what can you tell me about CoQ10? I haven't researched that yet. I know it is a possible Carnitine cofactor, but that is about all I know.