a nap taken
afternoon/evening when have either not had enough sleep the night before or expecting a v. late one...
been proven that 45mins to an hour is the optimal amount but as little as 20mins is still helpful if very tired.
more than 1hr 15 and you go into a deeper sleep and are likely to feel drowsy for a long time after you wake up.
tip: take a korean ginseng energy tablet right before your nap and it'll be
kicking in as you wake up :)