well as through time.

Dreaming and sleep are intertwined. Dreams occur mainly in the rapid-eye movement (REM) stage of sleep--when brain activity is high and resembles that of being awake. Because REM sleep is detectable in many species, and because research suggests that all mammals experience REM, linking dreams to REM sleep has led to conjectures that animals dream. However, humans dream during non-REM sleep, also, and not all REM awakenings elicit