I've had Chronic Fatigue Syndrome for such a long time but it was only diagnosed two and a half years ago. From that point on I've taken Vitamin B12 and it has been a God-send to me. I started off by having shots and after a few months I was swapped over to sub-linguals. It has made an incredible difference to my quality of life. However I'm now having huge problems sleeping. I do OK for a couple of hours and after that it really is a waste of time being in bed. I blamed all sorts of things but nothing is making it better. Finally in desperation I started wondering if the B12's were doing it. I can now see a couple of references to it causing insomnia on websites. Has anyone here had any experience like mine please? Does anyone know how long it would take for the B12's to be out of my system when I stop taking them?