Memory Consolidation
Deep sleep transfers learning from hippocampus to long-term cortical storage. Skipping sleep erases yesterday's study.
Glymphatic Cleanup
During sleep, brain cells shrink slightly, allowing cerebrospinal fluid to flush metabolic waste including amyloid proteins.
REM and Emotion
REM sleep processes emotional memories and creative associations. Dreaming serves biological functions beyond entertainment.
Practical Takeaway
Seven to nine hours is not luxury for knowledge workers. It is hardware maintenance.