The logic behind it is that research has shown that caffeine in the coffee takes about 20 minutes to kick in.. and in the first 23 minutes of sleep is when your body actually goes to rest before entering the the deep sleep cirle..
So, by doing this you actually double the effect of a power nap!
I've been having trouble staying awake after buka puasa so I gave it a shot.. and for the last 2 nights it has worked!! I could finally do my work until 1am and still wake up for sahur at 5am and even continue the day like normal..
Maybe you guys who face the same problem as me could give it a try.. ;)
Key note: Wake up before you go to R.E.M. mode..