Library · Physiology
Dreams
Make it clearer
Everyone dreams. The estimate is about two hours a night spent dreaming, though most of it may leave no memory by morning.
What happens inside has a name. During REM sleep, the stage of rapid eye movements, the thalamus, the station where signals from the senses normally enter the brain, becomes active and sends images and sounds to the cortex. With the eyes closed, the thalamus keeps feeding scenes to the cortex, and that is what fills the dream.
Dreaming happens in every stage, but dreams tend to be more vivid in REM. And it is precisely then that the muscles of the arms and legs are paralyzed for a while, which keeps a person from getting up and acting out what they are dreaming.
What dreaming is for is still an open question. Its exact purpose is unknown; it has been proposed that dreaming helps process emotions, but that is a proposal, not something proven.
In brief
Everyone dreams about two hours a night, though most of it may not be remembered.
During REM sleep the thalamus becomes active and sends the cortex the images and sounds that fill dreams.
With the eyes closed, the thalamus keeps feeding scenes to the screen.
Dreams occur in every stage, but they tend to be more vivid in REM, where paralysis of the arms and legs keeps them from being acted out.
Their exact purpose is unknown; one proposal is that they help process emotions.
Sources (1)
- National Institute of Neurological Disorders and Stroke, National Institutes of HealthBrain Basics: Understanding SleepPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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