Yes, black tea...interesting compound: Theophylline, also known as dimethylxanthine, is a methylxanthine drug used in therapy for respiratory diseases such as COPD and asthma under a variety of brand names. Because of its numerous side-effects, the drug is now rarely administered for clinical use. As a member of the xanthine family, it bears structural and pharmacological similarity to caffeine. It is naturally found in tea, although in trace amounts (~1 mg/L), significantly less than therapeutic doses. It is found also in cocoa beans. Amounts as high as 3.7 mg/g have been reported in Criollo cocoa beans.
The main actions of theophylline involve:
* relaxing bronchial smooth muscle
* increasing heart muscle contractility and efficiency; as a positive inotropic
* increasing heart rate: positive chronotropic
* increasing blood pressure
* increasing renal blood flow
* some anti-inflammatory effects
* central nervous system stimulatory effect mainly on the medullary respiratory center.
Caffeine has no effect on me whatsoever! I mean I can drink an espresso and go to sleep straight away. Black tea (not green) is what keeps me awake! If I drink black tea after 6pm, I am in for a long night... for energy levels and mental awareness, nothing works better than a glucose-rich drink for me. It all makes sense scientifically: glucose is a primary source of energy for the brain (and muscle cells), and black tea contains more stimulants.
Try doing some brain games u can increase your brain power, also one such that i tried recently was www.lumosity.com here u can get free brain games that will help you out. also do some physical exercise that u like ,go out for shopping or try any new recipe.
I'm a regular caffeine consumer. I try to avoid sugar with it, but at various times have included sugar with caffeine in my attempts to maintain an adequate level of brain function.
I would have to say, though, that I've empirically determined, at least for myself, that by far the most effective two methods for maintaining good mental function throughout the day are: 1) an extra hour and a half of sleep, and 2) exercise.
500mg of acetyl-L carnitine has seemed to have positive mental effects well beyond placebo for me. I've been taking that in the morning along with one cup of coffee (unsweetened except for some whole cream). I take other vitamins and supplements as well, although not the fistfuls I've heard some consume.
As far as other aspects of diet/exercise: low carb/high protein, make sure to get enough healthful fats, particularly coconut oil. Get up and move around as often as feasible, especially if you necessarily must spend a lot of time in a chair at a monitor/keyboard. Don't suppose that some intense exercise once in a while compensates for the lack of motion during the day.
And yes: think --- don't just be a passive absorber of sensory input. A recent encounter with some math problems has been salutary, except that sometimes I stay awake thinking about them when I otherwise would sleep!
Modafinil is quite effective and pushing you up to peak performance, and keeping you there for a few hours. One report in an informal survey in Nature magazine suggested some 25% of scientists (and presumably engineers) used it at some point (as well as Ritalin).