...While caffeine from coffee and tea dull the brain.
I do not remember that. It would be true if caffeine is ingested in excess, with high concentrations being above about 300 mg per day on average. But such an excess would not be the primary cause of the brain dullness, rather it would often disrupt the ideal sleep architecture in such a way that the brain functions would not be optimized.
Caffeine is rajasic and moderate rajas is very useful outside an Ashram, but after 12 AM or 2 PM it may become unhealthy, for the above reason.
Also, some qualities of coffee, the ones I'm consuming now, light roast, high altitude, arabica variety, have mixed rajasic and sattvic qualities.
