I have unstable angina that wakes me from a dead sleep and have wondered if this could be from the position or other.
I've had some experience with both angina and digestive issues. Naps have always made angina issues disappear, but have made digestive issues worse. If one has digestive issues, the absolutely worst thing one should do is lay down. I'd investigate digestive issues before checking out cardioi problems.
There shouldn't be any connection with a nap, but there could be from eating. Obviously it's normal to feel tired after eating because a lot of our blood is diverted to digest the food we just consumed. This can put extra stress on the heart, enough to bring on angina. If this is the case then you should also have the same symptoms after exertion, such as walking up a hill.
While it is possible this represents unstable angina there are other possible causes.
Angina is diagnosed through a sublingual nitroglycerine challenge. If the pain is reliefed upon takin a sublingual nitro there is a high liklihood the problem is angina.