Christopher Ketcham at Men’s Journal has written a article on power nap. In our previous introduction of power nap, polyphasic sleep involves the sleep pattern of 90 minutes. In this article, they have looked into compressing the nap into 20 minutes, by going through first two out of five of sleeping stages:
… Here’s how the power nap works: Sleep comes in five stages that recur cyclically throughout a typical night, and a power nap seeks to include just the first two of them. The initial stage features the sinking into sleep as electrical brain activity, eye and jaw-muscle movement, and respiration slow. The second is a light but restful sleep in which the body gets ready — lowering temperature, relaxing muscles further — for the entry into the deep and dreamless “slow-wave sleep,” or SWS, that occurs in stages three and four. Stage five, of course, is REM, when the eyes twitch and dreaming becomes intense.
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…
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.
Snooze, You Win – Improve your mental and physical performance by power napping – [Men’s Journal]