Could this be stress? I don't feel stressed, but lately I have had concerns regarding the sudden death of a couple of friends my age (40ish).

yes you should immediately consult a doctor numbness in left arm is a major symptom of heart disease or blockage.

Mainly the age of these heart blockages is between 40 to 50 years,so you should immediately consult a doctor numbness could due to blood circulation. do more exercise and less fried and spicy food. try to sleep early (before 11pm) , more fruits and stay happy. (11pm - 1am is the time for liver to detoxin) I'm sorry to hear about your friends. Stress can cause a lot of different problems, so it's possible that it's related to the symptoms you're having. On the other hand, if something neurologic is causing your symptoms, it is better to treat it sooner rather than later. I would see a doctor to get checked out. Hopefully it is not anything serious. Do not walk, run to the nearest doctors office, urgent care clinic, ER. I couldn't help but notice that your avatar showed a person who was black. Traditionally, black Americans have the highest incidents of high blood pressure and stroke. numbness, especially one sided is indicative of TIA and stroke. Other symptoms include but are not limited to slurred speech, blurred vision, difficulty finding the right words/remembering, etc. Please, I beg you go see your MD. Your life could very well be at risk. You don't want to know how many 40 year old patients I've have that thought they didn't have anything wrong with them. Or thought it was indigestion only to find out later, (to late) that it was a stroke and then it happened again and then they had to be feed with a stomach tube and ended up wearing diapers. Good luck to you.