“…In addition to its major role in cardiac physiology, diagnosis, and therapy, adenosine also has important roles in the physiology of learning, memory, and sleep [ 9 , 10 , 11 ]; in the pathophysiology of brain disorders such as Parkinson’s disease, drug addiction, and depression [ 12 , 13 , 14 , 15 , 16 ]; and in the regulation of anti-secretory effect in the stomach, of anti-epileptic effect, and of renal functions [ 17 , 18 , 19 ]. Furthermore, because adenosine is a product of ATP degradation, its release from cells can also be correlated with a high metabolic rate or metabolic stress [ 20 ]. The extracellular concentration of adenosine in the brain has not only been linked to sleep regulation through slow wave activity [ 9 ], but has also been shown to modulate it [ 10 , 11 ].…”