Lucid Dream = More energy in shorter time?

I've noticed that in the 2 times I've had a Lucid Dream that when I wake up, Although I only slept 2 or 3 hours, It feels like I've had 10 hours of sleep.

The energy is powerful. Why is that?

Maybe if we could control when we have lucid dreams perfectly that we can practically use lucid dreams to replace sleep and get like...1 hour of sleep of day which would help a lot of students in studying since that 1 hour would feel like a lot of hours. And anyways, we can study in our dreams...jsut without a perfect recollection of the textbook.

I noticed that today too, when I awoke after my first lucid. I felt extremely happy, when I should be feeling ultra tired and grumpy.

No doubt that you feel more well-rested after experiencing an LD than a regular dream. Perhaps it may have to do with increased REM activity while LDing?

Scientifically, there isn't anything going on in a lucid dream vs. a non-lucid that makes sleeping more efficient. In the long run, you'll still need the same amount of sleep as everyone else. If I had to take a stab at it, I'd say that the excitement and sheer joy of the first couple lucids put you up on cloud 9, as they are apt to do. :)

Mario92 is probably right, it's the adrenaline rush of having a lucid after however long trying.