Is sleeping on my back the reason for my hair loss?

I've started to lose more hair on one side of my head, and I take that side as I sleep on my back. I've also recently gotten migraines and my doctor said it could be related to my hair. I thought that it was due to stress at first but I've noticed that the hair that is getting cut by my hairdresser on that side is more than the other side. What should I do, my hair is my pride. I also have occasional itchiness but I have dandruff since forever so I attribute the itchiness to that.