REM sleep paradox: Dreaming may drain the brain’s energy even as fuel supply rises

Scientists discovered a surprising energy paradox in the brain during REM sleep, the stage most closely associated with dreaming. Blood supply to the brain begins increasing even before REM starts, but neurons’ immediately available energy, measured as ATP, then drops. The finding suggests that dreaming may require such intense internal processing that neurons consume energy faster than it can be replenished.

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