Naps
Interesting article here about the benefits of napping. Here was something interesting that I’d noticed but couldn’t figure out. Usually when I nap, I wake up pretty refreshed if it is just a 20 minute one, but sometimes I get real lethargic and am stuck like that for awhile. Well here's why:

There is, however, a pitfall in all this sleeping around. You have to carefully time the duration of your nap in order to avoid waking in slow-wave sleep. This can produce what's known as sleep inertia. That's when the limbs feel like concrete, the eyes can't focus, the speech is slurred, the mind is sluggish. Sleep inertia can ruin your day. You must keep the nap to 20 minutes or slightly less, and if you need the extra sleep, wait until the 50-minute mark. This will safely keep you on the power side of your nap.

OK, I'll nap longer then. Via Newmark's Door.