A power nap takes 10-20 minutes of sleep, when the brain releases theta waves, and falls into a relaxed state of mind. This state ends before the occurrence of deep sleep (or slow wave sleep).A power nap gives you an instant flow of energy as it increases alertness, stamina, motor learning and motor performance. It also improves muscle memory and it clears the brain from unnecessary built-up information, which helps long-term memory. Avoid nonetheless napping for longer than 30 minutes: after that time your sleep state will progress to the second stage of sleep in which one feels sleep inertia. It would take you more efforts to shake that off.
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