I've noticed similar but more subdued effects when going on and off coffee. I don't feel any physical effects from coffee (as long as I stay below about 3 cups)

I've noticed similar but more subdued effects when going on and off coffee. I don't feel any physical effects from coffee (as long as I stay below about 3 cups), so I often take long breaks from it when it simply isn't convenient for me to drink it. I've noticed that when I don't drink coffee, not only do I have trouble focusing, but I'm less likely to exert the effort to try new things or put the effort into understanding difficult subjects. I also feel the same trouble even staying awake that you noted. I get significantly more done when I incorporate coffee into my day. Another thing that works for me is formulating a plan of action before I have any coffee, and then drinking it when I start. The caffeine and the ritual put me in the right mindset to get real work done.