I have suffered over the years with sciatica pain, especially in the morning, after a nights sleep. I can be in agony for up to 45 minutes, then it goes away and I can cope with the rest of my day. I tried seeing several doctors and paid for physiotherapy with no results.
One evening, I was so fed up that I could not face another night in bed, knowing what would await me the next morning. I decided to sleep in the reclining chair in the lounge. It does not sound very comfortable, I know, but to my surprise, the next morning there was no pain, just slight stiffness which disappeared after 10 minutes. I thought it was a fluke, so I did the same thing for a few nights and guess what; no pain.
I was tired at work and missed sleeping in my bed. I went back to the physiotherapist and the doctors and explained what I had discovered, but they couldn't understand it. Nobody seems to know why this works for me, but it does.
I have adapted my bed, pushing it up against a wall and arranging lots of cushions so it resembles a sitting position. It is not as good as the chair, but also not as painful the next morning. Maybe lying flat is not providing enough oxygen into my spine or maybe it's a sleep position thing. It works for me, so maybe you could try it too.