Caffeine directly effects the adenosine receptors [1] which are what regulates sleep and wakefulness [2]. [1] http://www.ncbi.nlm.nih.gov/pubmed/20164566 http:

Caffeine directly effects the adenosine receptors [1] which are what regulates sleep and wakefulness [2]. [1] http://www.ncbi.nlm.nih.gov/pubmed/20164566 http://www.ncbi.nlm.nih.gov/pubmed/20164566 [2] http://www.sciencedirect.com/science/article/pii/S030100820400125X http://www.sciencedirect.com/science/article/pii/S0301008204...