What causes a 'Sleep Anxiety Disorder'?

For several nights I'd woke in the middle of my sleep moaning. My heart was thumping I could thought my chest was breaking out. I'm having nightmares!!! The nightmares varies. Once, I dreamed about seeing two, slender hands of a woman pinching my, of all the body parts, nipples! The intensity of squeezing increments each second. I was struggling to fight back but I could not bring myself or even just one finger to move. I was praying and saying "In Jesus Name" to fight off the fear. My sister, good that we were sleeping together, woke me up in time when I was about to whimper. Fear, anger towards my unfriendly visitor and courage mixed up.

The other night when I was in our dormitory, I dreamed of having a cat beside my bed. I was trying to drive this cat away but he was just there staring up into the ceiling. I grabbed the cat's head and it was like I was holding a round steel, I was shoving the cat but it was standing so firmly. When I calmed down, the cat was slowly sitting down as if taking a nap beside me on my bed! I pushed the body trying to throw the cat outside my bunk bed but the cat was fighting, grabbing my arms with the sharp nails, it was scraping me. That was the time I'd woke up whimpering. It was very difficult for me to return to sleep. I'd switched position several times. They said to turn over your pillow up side down and so I did. But I could not sleep anymore. The feeling of anxiety never left me until dawn. It was maybe past four in the morning when I was able to get back to sleep.

Morning came and I woke up having dark circles on my eyes.

Before I used to believe of what I heard that going to sleep with a very full stomach will likely cause a person to have nightmares. My sleepless nights prove that this is just a myth, I ate my supper before six and I went to bed at half past eleven and that for sure I am not full.
Researcher said the cause of nightmare is not known for certain. There are various conditions that contributed for having a restless night or bad dream. It could be triggered by post-traumatic experiences, stress, can also be a side effect of abusively taking drugs. Withdrawal from alcohol and other medication can sometimes cause nightmare. Some thinks that artistic and creative people are at high risks of experiencing nightmares as these people are highly sensitive and imaginative.

With all of the above mentioned causes of bad dreams, I am certain the cause of my dream anxiety disorder does not stem up from taking excessive drugs, alcohol withdrawal or any post traumatic experience. It might be stress because of work pressure and problems I am facing. But I would like to say that I'm having bad dreams because I am artistic and creative. (lol)