Ñukñu’s Reviews > Why We Sleep: The New Science of Sleep and Dreams > Status Update

Adenosine build up and the circadian rhythm are the two key factors in sleep. Sleep is universal among all animals. NREM and REM sleep work together for emotional regulation. REM sleep is crucial for the development of the prefrontal cortex. Caffeine has a half-life of seven hours; caffeine blocks adenosine receptors.