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Keywords:

  • adenosine;
  • enzyme;
  • prostaglandin (PG) D2 and E2;
  • receptor;
  • sleep and wake

Abstract

Sleep is perhaps one of the most important and yet least understood of the physiological functions of the brain. Sleep is essential for life, but we still cannot answer even the simplest questions about sleep, such as “what is sleep?,”“why do we need to sleep?,” and most importantly, “where and how are sleep and arousal regulated?” In the mean time, the number of sleep-disorder patients has recently been increasing exponentially and now exceeds more than 25% of the total population in most countries. More than 107 different sleep disorders have now been described, but in most instances, their etiologies are not yet clearly understood, simply because basic sleep science research has really only just begun. In the early 1980s, my colleagues and I at Kyoto University serendipitously discovered that prostaglandin D2 induced physiological sleep in rats and monkeys, and subsequently we elucidated the molecular mechanisms underlying sleep–wake regulation by prostaglandins D2 and E2. In this review, I start with a brief historical account, follow it by our ongoing work on prostaglandins and sleep, and finally close with a few remarks on the future prospects of sleep science.