Hello and welcome to eHealth Forum!

The symptoms that you describe (go to sleep in a totally dark room I wake up to find myself gasping for air and screaming, it kind of feels like a hallucination; I’m drowning or something and the only way to stop it is to find a light switch and turn it on) come close to what is called achluophobia or fear of darkness, though they are not the classical symptoms.

High level of emotional stress, traumatic experience in the past in the dark etc is known to precipitate it. Sleep studies, hypnosis, and cognitive behavioral therapy which helps you to analyze the cause of your anxiety and teaches you to alter your thinking process are the usual methods employed to understand why you have this problem.

You need to discuss this with your doctor and get help from a psychiatrist to overcome anxiety. Until you get the appointment, it will help to sleep with a night lamp on. Hope this helps. Take care!