I hope you are doing well. I think you have generalized anxiety and it is manifesting itself as a fear. Some people have other irrational fears, fear of going outside, fear of certain foods etc, which make no sense, but are fears none the less. I believe you need to find ways to take your mind off thinking about not sleeping in such a negative light. As you wrote, you have no trouble sleeping, so obviously this is not keeping you awake and it sounds as though you have learned to think of sleep negatively. You need to start to view sleep as a positive thing. I myself love lying in bed and slowly drifting off, letting my mind go and just enjoying the warmness of my bed. Enjoy life, right now it seems as though your mind is caught in a rut of thinking about sleep, Enjoy life and all it has to offer, exercise, spending time with family, watching tv with loved ones. Enjoy life because it is short and you only have one. I wish you all the best and remember, once you start "forgetting" about your negative sleep thoughts, you will be surprised how quickly you forget about sleep at all.