How bad is it for a 27 year old to get stable angina (chest feeling heavy) after pulling an all-nighter? Also happens when the weather is really hot.

Angina. Angina is a very serious condition caused by a blockage in one or more coronary arteries. At your age this would be very unlikely. For diagnosis of your symptoms a physician would take a thorough history, perform a physical examination and order appropriate tests in order to make a diagnosis and then treat you. Chest heaviness may be a variant of asthma.