十万个为什么·科学启蒙30篇（3）

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人为什么会做梦

Dreams occur mainly during REM sleep, a stage when brain activity resembles wakefulness but the body stays paralyzed.
Scientists think dreaming helps sort memories, strengthen learning, and process emotions from the day.
During REM, the brain reactivates neural pathways used while awake, linking new experiences to older knowledge.
People who learn a skill and then sleep well remember it better than those who stay awake all night.
Strong emotions—especially fear or stress—often show up in dreams because the amygdala stays highly active then.
Not everyone recalls dreams, but nearly everyone has them unless brain injury or certain medications interfere.
Lucid dreaming happens when a person realizes they’re dreaming and can sometimes guide the story consciously.
Nightmares may help prepare us for real threats by safely rehearsing danger responses in the sleeping brain.
Dream content changes with age: children dream more about animals and family, while adults dream more about work and social life.
Though dreams feel vivid and real, they usually last only 5–20 minutes and fade quickly upon waking.