There are probably a number of causes, but coffee may be one of them. Don't be radical, but if you're having too much coffee, I'd suggest cutting down to just one coffee in the morning. It will take a bit of effort but may help you concentrate.
I'd suggest gradually cutting down to none. Apparently the alertness and general cognitive enhancing properties of caffeine don't really exist and all that people are noticing is the effect of the caffeine on their caffeine withdrawal symptoms.
OPs point is that your brain adapts to the level of caffeine you're ingesting. So if you're used to drinking coffee then you're basically at the same level of alertness/functioning that you were before you first started drinking coffee (i.e. before it became habitual). The effect you notice from the first cup of coffee in the morning is really just the coffee counteracting the withdrawal you feel after ~6-8hrs of no caffeine.
This is clearly unsubstantiated - the benefits of coffee are very clearly outlined. Maybe some people who drinks too much are experiencing the withdrawal, but if you do not over-do it, there is a 90% chance of feeling more alert when you drink coffee.
These are just two of the first studies I found. There are plenty of others.
if you do not over-do it, there is a 90% chance of feeling more alert when you drink coffee.
90% of statistics are made up on the spot. If you're going to acuse me of making shit up on the spot maybe you shouldn't do it yourself? Feeling is the operative word in your statement.
I'd suggest gradually cutting down to none. Apparently the alertness and general cognitive enhancing properties of caffeine don't really exist and all that people are noticing is the effect of the caffeine on their caffeine withdrawal symptoms.