Effects of Adenosine on the Sleep-Wake Cycle

Sleep and wakefulness are multifactorial, complex and well-regulated physiological processes that occur in all living things. Environmental and genetic factors that affect sleep and wakefulness can change the cycle determined by the circadian rhythm and the duration and intensity of daily brain activity. Considering the necessity of good sleep for health, it is clear that defining the factors that regulate the spontaneous sleep-wake cycle is important for the prevention, diagnosis and treatment of many sleep disorders. The facts that the extracellular concentration of adenosine which is defined as an endogenous sleep factor increases during long-term wakefulness, especially in the cortex and basal forebrain, and decreases during sleep, and in addition, caffeine, which is frequently consumed in daily life, acts via this molecule, indicate that it is a molecule that should be considered in the homeostasis of sleep. In this review, studies examining the regulation of the sequential sleep-wake cycle and the role of adenosine in this regulation are summarized.