Of course you could still go for the famous 20min powernap. You don't go to deep sleep there.
Here's the thread that I was talking about. The wikipedia article here is also good as a basic primer.
But here's why it's important for athletes to get to N3/N4 stage sleep, even during naps:
HGH is synthesized and secreted from the anterior pituitary gland in a pulsatile manner throughout the day; surges of secretion occur at 3- to 5-hour intervals. The plasma concentration of GH during these peaks may range from 5 to even 45 ng/mL. The largest and most predictable of these GH peaks occurs about an hour after onset of sleep. Otherwise there is wide variation between days and individuals. Nearly fifty percent of HGH secretion occurs during the third and fourth NREM sleep stages.
I started doing this between classes during college, and continue to do it to this day after work. I usually wake up naturally after 20-30 mins. Sometimes, if I'm really tired, I might sleep 45 mins.
I used to set alarms, but now I just lay down, relax, and there's this point where I feel like I slightly drift off into a dream. It feels like a little jolt, then I become conscious again, then I get up. The dreams are always super weird, but I always feel great for another 5-6 hours afterwards.
I fell asleep on the way to a powerlifting meet repeatedly for a couple minutes. When I ended up actually getting there, I was pretty refreshed. And I'd only gotten about two hours of sleep the night before.
Naps save lives.
Re: the longer naps, Steve do you not find that if you nap for 1-2 hours you wake up super groggy and disoriented afterwards? That's always been my experience.
http://www.myzeo.com/ that uses EEG from a headband to determine sleep state. As it turns out, for me my sleep cycle length actually changes over the course of the night, starting out about 110 minutes at the beginning, and ending around 75 minutes near the end. This is also very consistent from night to night, within a few minutes each way. Sleep cycles also tend to be different for napping then they do for night time sleeping. Most consistent nappers enter REM immediately after falling asleep for a nap, while most enter deep sleep first when going to bed for the night.
The gizmo takes a bit of getting used to for sleeping, but it only took a couple days for it to feel normal to sleep with it. It has also given me some interesting results, for instance I tend to get about 10 minutes more deep sleep on nights that I train. This makes sense given that deep sleep is most restorative to the body and is when a bunch of hormones like HGH are released. I am also about to start an experiment to see how ZMA effects my sleep cycles too. Well worth the $100 it cost IMHO.
These cat naps or power naps of only 20 min or so just are not possible for me. Maybe for someone who works 8 or 10 hours a day, but when its midnight and you've already worked 16 and realize you still have a normal persons work day left before you get off 20 min does not help. Good info on sleep cycles though, i was under the impression it took 4 hours of solid sleep to do any good. Now i have an excuse to tell my wife why I sleep in the mornings instead of mow the grass.