Years ago when I quit smoking, I did it all of sudden (in two times, second one forever)- I did not know at the time but it was Uranus aspecting my Neptune that stands for addictions. So my experience was like a thunderbolt hitting, and I do not remember being too sleepy. Nervous, yes I was, like excess of Air element. I ate black licorice (no sugar) in place of cigarettes, licorice raises blood pressure and is stimulant so probably it counterbalanced fatigue.
I also quit caffeine for my personal choice, later on. I remember, I was really tired like a zombie waking up in the morning, the first couple of weeks, then I slowly adapted. Influence was not coming from Uranus so this was a longer and most stressful process.
I think it may be a normal reaction by your side.