REM sleep is not the only time during sleep when we dream. Indeed, if you use a liberal definition of dreaming as any mental activity reported upon awakening from sleep, such as “I was thinking about rain,” then you technically dream in all stages of sleep. If I wake you from the deepest stage of NREM sleep, there is a 0 to 20 percent chance you will report some type of bland thought like this. As you are falling asleep or exiting sleep, the dream-like experiences you have tend to be visually or movement based. But dreams as most of us think of them—those hallucinogenic, motoric, emotional,
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