Hello,
I hate having to repeat what you've already probabbly heard a bunch of times - but all these fears are basically what anxiety is. It's an uncontrollable and very often unreasonable fear of things that might happen (or might be happening). When you are scared, your body releases the hormones that prepare your body to respond to the situation and this response involves faster heartbet, faster breathing - your muscles getting rigid... What you described happening to you at night sounds like what people experiencing panic attack feel.
Have you talked with your physician about the anxiety problems? Or are you thinking about getting any treatment for anxiety itself - not the physical symptoms anxiety manifests itself through? I suggest you to do that before anything else, but in the meantime, when you're lying in bed at night, expecting anxiety attack to happen, start practicing relaxing breathing techniques. Focus on your breathing, try to slow it down and that will help you get your mind of anxiety symptoms.