The only catch is that you have to carefully time your nap to avoid waking in slow-wave sleep (third stage), which can produce sleep inertia. My question is, how to time it exactly to avoid being wake up in third stage when you are unsure when you fell asleep? It is not a easy task. Even this power napping is working – It will be hard to get implemented. The five stages repeat every 90 to 120 minutes. Stage one can last up to 10 minutes, stage two until the 20th minute. Extenuating circumstances, like manning the controls of a jet, aside, experts believe that the optimal power nap should roughly coincide with the first 20 minutes in order to give you full access to stage two’s restorative benefits… Snooze, You Win – Improve your mental and physical performance by power napping – [Men’s Journal]
