Somniphobia or hypnophobia is the fear of falling asleep. It can be caused by many things such as the fear of losing control. There are CBT therapies for this fear. You need to see a psychiatrist. As Julie said there are meds to help you relax and be less anxious about bedtime. You should not put this off. It is terribly unhealthy both mentally and physically. You need sleep.
You are not alone. I think you should seek therapy. In the meantime, know these facts: Your body requires sleep to function properly. Sleep is a natural thing for your body to do when you are tired. Healthy people do not die in their sleep. They always wake up naturally when their bodies have had enough rest. Always. Remeber these facts when it's time for bed, and rest well!
Well one thing i can tell you right now is that sleep is far from 'nothing'. When you fall asleep your brain is just as active as when you are awake. You go through a cycle of different levels of Consciousness throughout the night and regularly go into REM which is where you are dreaming. The vast amount of dreams we dont even remember but trust me that you are dreaming and probably having several, if not more every night.
It is extremely important for the brain to go through this process every night, as it is the brains way of filtering all the imformation that has gone on throughout the day. It is like a filing system, the brain stores or discards what it does or doesnt need. Also as soon as you fall asleep the brain releases a chemical into your blood stream that tells the body to start repairing and healing all the little or big imperfections within you ie; cuts, infections, restoring and growing bone, making new cells etc etc..., and is the time that the body grows most. Sleep is essential for good health in both mind, body and spirit.
When you are asleep you are certainly alive and your body and mind is working very hard to make sure you are healthy and happy. Even a ferw hours of sleep deprivation each night can cause you to feel very run down and anxious, depressed. You may start to develop more colds and infections and just feel like how you are feeling now....
My advice would be to you to go and see your doctor, tell him/her exactly what you have told us here and i'm sure he may refer you to a therapist, who will be able to help you deal with your anxiety issues and get to the bottom of this, because frankly you trying to desprately stop yourself falling alseep every night is making yourself very ill and causing yourself a great deal of emotional ditress and what are you going to do this for the rest of your life? what a unhappy and distressing life that would be.... so please go see your doctor. he may even give you some med's to help you relax which i think in this situation is a really good idea.
I do hope you manage to overcome this fear. Please let us know what you decided to do and good-luck and restful night sleep tonight and in the future...... take care
Julie