The best known of these sleep-regulating substances (although probably not the only one) is adenosine. Adenosine operates as a neuromodulator in the brain, and has the effect of inhibiting many of the bodily processes associated with wakefulness, particularly those involving the neurotransmitters norepinephrine, acetylcholine and serotonin.
Adenosine levels in the basal forebrain rise as sleep debt builds up, and then fall rapidly during the subsequent sleep period. Adenosine is created over the course of the day, as a natural by-product of using up our internal energy stores (it forms the core of adenosine triphosphate (ATP), the energy-storage molecule that powers most of the biochemical reactions inside cells). This supports the theory that the body's regular desire for sleep stems, at least in part, from the brain's periodic need to replenish low stores of energy: in 1995, Craig Heller and Joel Benington proposed this theory, based on the observation that, as the brain’s glycogen energy stores are depleted throughout the day, extra-cellular adenosine builds up, and then, during sleep, the adenosine is removed and replaced by new glycogen.
Adenosine, the best-known of the sleep-regulating substances involved in the homesostatic sleep drive
Experiments have definitively shown that high levels of adenosine lead to sleepiness. Studies in animals have shown that blocking adenosine's actions in the brain increases alertness, while injections of adenosine or similar compounds induce apparently normal sleep. Also, adenosine concentrations in the brain shoot up dramatically in animals forced to stay awake. Commonly used stimulants, like the caffeine in coffee, tea, cola and energy drinks (as well as the theophylline in tea and chocolate), work as adenosine antagonists or receptor blockers, inhibiting or dampening its sleepiness effect, and thereby maintaining alertness.
[Solved] Administration of a(n) ________ would be expected to promote sleep. A) adenosine[Solved] Activation of adenosine receptors may increase sleep by A) excitation of hypocre
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