Is sleeping at night a "pain in the neck?" I feel like 90% of people that I see for physical therapy say that have difficulty sleeping due to not being able to find a comfortable position. Most of them have neck or back pain.

I hear all the time that patients “have tried every pillow out there.” Poor sleep can be contributed to many factors including an old mattress and or even poor posture. I, too have suffered from neck and back pain with sleep.
I went back to a spine course, where it reminded me that you do not need a lot of support for your body while sleeping, but you need the ‘right’ amount of support.
You really only need enough support to fill the “space” between your spine and the bed, mainly in the areas of the natural curves we have in our necks and our backs. For example, you have a ‘natural curve’ in your neck so when you are lying on your back, you just need enough support to ‘take away the daylight’ between the neck and the bed.
I was having neck pain and difficulty sleeping. I noticed my pillows were too soft, did not provide any support and too fluffy or firm support made my neck flex. I also noticed that I tend to bend my neck to the right side throughout the night. I began to use a blanket (actually a throw blanket) for neck support by scrunching up the blanket right at the curvature of my neck. So with using a throw blanket and intermittently changing my neck position to neutral versus bending neck to the right, I noticed that my neck pain has gone away and I have not had neck pain since.The pain did not disappear overnight though. It probably took about a month to feel any change. So I challenge you to try these two things for the next month and see if you feel any changes in your neck symptoms.