Depression is when you have no power to do anything. You lie in your bed, too tired to shave or shower. You don't care about anything.
And, I'm sorry, but I cannot post any links or point to any book that proves what I've said, but I've taken courses in psychology, and it is from what I've learned there that I spoke. I'm not making something up, just to screw around.
When you stop jerking off, or do it more rarely, you will notice that you'll get horny less often.
If you start to ejaculate every other day for some time, you'll notice that you'll get quite horny only after 1, 2 or 3 days.
When I made effort to drop the orgasms, I found that it could go a week without me feeling the need to do any sexual activity. And if I started to have orgasms on a regular basis again, I found that I after a while got horny more quickly.
And about the depressions, I'm talking of a long time here, not 2 weeks. I've experimented on this particular thing for a very long time now, and noted the effects and such.
First, you get more energy, and so. But, then, when you don't have orgasms, you're body will start "saving", and you won't get the energy you want anyways.
The sexual power will reduce itself accordingly to the frequency of your orgasms. It is in the "high-points" of the cycles you can extract extra energy from this, when your body is expecting an orgasm and have built up extra energy, but the orgasm doesn't come. Then you'll have a surplus of energy.
But the body "learns" and it won't produce that amount of energy next time.
So, as the distance between the orgasms become greater, so does the rate of speed that the body builds up energy drop.
After a while, you'll notice that you'll get no more extra energy and you won't be horny, either.

The thing is, that the extra sexual "kick" you feel when the body has saved up energy for the orgasm, and it doesn't come, give you a boost in your overall activity - because of the extra testorone you have in your body (running faster, lifting heavier things etc) and (this, researchers have not been able to grab, yet) the "other" type of energy, the "mind-energy" that gives you more powerful meditations, a quicker brain etc. (allthough being able to think quicker also has a connection to the testorone? I'm not sure about this one.)
But it only last for a little while. The body rids of this extra energy quite fast, and starts the rebuilding process once again, according to the time-limits between the orgasms it is used to.
The energy you use to live your life and to read books and to keep your heart beating is not only sexual energy, cause then I'd already be dead, or at least not half as smart as I am today.
Jerking off to and .avi film, or actually having sex both gives orgasms and renews the cycle. Writing, reading or lifting weights does not give orgasms, and hence the body will not continue to build up the sexual energy you benefit from.

We're quite the mammals, really. The body simple wants to breed. 8)

I'm only sharing my own experiences here, of what I've learned and felt.
I'm not trying to "dictate rules", or "tell you how it *really* is", because that I think noone will be able to do, ever.