Hi Doctor, I am 40, male. For the last 8 years, I have been experiencing a strange condition. When I sleep on my left-side, I have a nightmare that wakes me up and is followed by a severe headache. This condition will sometimes switch sides i.e. I ll experience it on my right-side and the left-side will be okay. But 80% of the time, I ll experience it if I sleep on my left-side. I also have a chronic Hepatitis B. I saw some doctors and they honestly have no idea. I don t know whether Hepatitis B can have a role in this or is it due to a brain tumor? Worth mentioning that I do not suffer form any sort of depression or stress and live a very happy life. Please suggest. AbdurRahman, Kabul