This is what I look like since I turned 22 when I dont get enough sleep.

*Eyes sunken way in.
*dark circles.
*area between nose and forehead is sunken in.

How can I prevent this from happening and why does it happen?

The best way to prevent this happening is to actually get enough sleep. And drink lots of water. Both.

4 hrs of sleep and you are asking this question???
Water and sleep and sunscreen :)
Since I turned 23, I had to get at least 6 hours of sleep, and then when I turned 26, I started to get lines and bad skin, so I stopped tanning and started to eat rite and drink looots of water. A year later, I actually look better than when I was 25 - 26 :)

OK, so what are they?

Your body is showing that is needs more sleep! If you don't have time to sleep much at night, try getting a nap in during the day. I'm the type of person that NEEDS at least 8 hours of sleep and sometimes I'm STILL tired. I've actually been to the doctor for being so tired and nothing was wrong.. I'm just a tired person! Anyway, every now and then I'm fine with not much sleep, but if it becomes a habit and I keep doing that, I start to get dark circles under my eyes and my skin looks so dull and my eyes look sleepy in general. It's just our body's way of showing what happens when we don't get enough rest.. you just start to LOOK tired. Try to find some more time to rest :).