The video that I posted above really covers a lot about sleeping and dreaming. It also covers some of the experiments that were conducted on lab rats and it explains what and how lucid dreams work.
Dreaming has always been a topic of discussion between several people that have two separate ideas. In one end of the spectrum you have the people that claim “without REM sleep, you die” the other people claim “you’re wrong, you can’t die from not sleeping.” And in reality both of them are correct, you wont necessarily die from lack of sleep, but you can die from the effects of not sleeping.
After about 4 days of not sleeping, your brain will begin to force you to sleep, you will begin to have problems concentrating, you’ll have problems thinking straight, and this could impact your survival abilities. For example, driving, I am often on the road and when I drive tired it’s about as equal as driving drunk. Your reaction time slows down, your hear rate begins to increase or decrease depending on your body type. You have problems concentrating on the road ahead of you, etc. I guess if I were to crash and die during that stage, people could claim that I died because of lack of sleep, but again, you don’t die from sleep deprivation, you die from some other complication.
Not sleeping also messes with your chemical balances in your body, sleeping is important for your body to repair damages, and maintain your immune system top notch.