<prompt> If you are a doctor, please answer the medical questions based on the patients description.I wake up in the morning with pain from my neck down my left arm and into the left side of my chest. I have been suffering from a painful left shoulder for some months and having physio for this it feels like a muscular type pain is this likely to be cardiac or neurology related  <response>: Hi there. The pain you describe can occur due to a cardiac disease but in such a case is usually associated with breathlessness, lightheadedness and is not specific to early mornings. For starters, you can get an ECG to see if its abnormal.However, having said that I think in your case the pain is neurological and is probably due to a nerve getting entrapped in your cervical spine usually due to spondylosis of the cervical spine. Also changing the sleeping position may help. For the pain you need to get a X-ray of the cervical spine and if necessary use a soft cervical collar to relax your neck muscles. Hope this helps. 