I am a physical therapist, and I have suffered from headaches for many years.  I bought this pillow (I am a side sleeper) and my headaches have decreased by 75%!  I used to have palpable muscle spasms in my neck and upper back muscles, but they are now gone!  My only complaint is that the pillow only lasted about 6 months before the height seemed to decrease, but I bought another pillow to replace it because it has helped my neck and sleep!