Downside of being caffeine free

Yes, that's right, I can now claim to have beaten the caffeine thing. Once I got the hang of it, it was all quite painless really. The downside is that last night I made a cup of filter coffee after my dinner as usual only I accidentally used the wrong coffee. Normal coffee rather then decaf. I didn't think much of it at the time as one cup of caffeinated coffee wasn't going to kill me and probably wouldn't make much difference to my digestion. It was not until I went to bed that I realised the difference. It took me at least 3 hours before I finally went to sleep. I couldn't believe it, I'd never had problems sleeping after coffee before and always thought people who said coffee kept them awake were exaggerating but there I was wide awake and concious that I was going to have to get up in another 4 hours. Best not make that mistake again.