That's what I was getting at though, the "immediate" effect could be non-existent because you already have adapted a tolerance (early as 10 days by some studies

That's what I was getting at though, the "immediate" effect could be non-existent because you already have adapted a tolerance (early as 10 days by some studies). If not, you should be able to test easily just by judging your mood about 45 minutes after your coffee.