This may not be triggering at all, but I wanted to be careful

where to start... uummm... well...
All my life I have had a problem with sleeping. I have always slept VERY lightly.. waking at the slightest sound... I have had to "work" at falling asleep and never have slept very deeply.
Recently I started taking a medication that makes me drowsy and at first I was alarmed about dreaming... and then it turned into anxiety because I was falling so deep into a sleep.I would sleep for 2 or 3 hours..and startle awake suddenly.. only to be wide awake for a long time after,feeling anxious.
I mentioned it my therapist.... here is what we decided is going on; i have been conditioned to be afraid to close my eyes at night.. afraid to let my guard down...afraid to NOT be aware of my surroundings.
I do not yet have memories of my father coming to my room at night..I think it was in his bedroom.. my parents bed... most of the time.I do recall being awake in the wee hours listening to him because he was up too... sitting in his chair.. flicking his lighter open and shut.. I hate that sound!
I remember being afraid to let him know I was awake... I would even hold my breath as long as I could and breathe very slowly and quietly to try and keep him from noticing me. His chair was just outside of my bedroom door.
My T asked me what am I afraid of NOW that keeps me from sleeping..and I had to say nothing.. absolutely nothing frightens me about sleep....but my body is so trained to be this way... one of those inappropriate coping mechanisms... it was good then. but isn't working for me now.. not needed..
This theory makes sense to me.. that my sleep disorder was me being hypervigilant... scared... and now I can see how my body and subconscious mind both have been so much in the habit of it that it has continued all these years needlessly...
Any thoughts? Input? ideas on how I change it NOW? All comments welcomed and appreciated
Peace to all.. Faith