Caffeine doesn’t give you energy. It boosts neurotransmitters such as dopamine that is known to affect concentration, while blocking adenosine receptors in the basal forebrain, are what typically signal the brain when it’s time to go to bed.
http://tuftsjournal.tufts.edu/2009/03_1/professor/01/
ref - https://www.reddit.com/r/todayilearned/comments/i5syca/til_that_caffeine_doesnt_give_you_energy_it/
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