this article, the hormone cortisol is directly correlated to death by heart disease. In fact, you have a five times greater chance of dying by heart disease if you have high levels of cortisol. What causes high levels of cortisol? Stress.According to
(What is not mentioned in the article, is that even low-grade sleep deprivation can also cause high levels of cortisol- because it puts stress on your body). Even more interesting (to me at least) is that high levels of cortisol are related to obesity (especially belly fat), and poor metabolism. So you can see how all those things might equal a higher risk of death from heart disease.
Wishing you heart health (both literal and metaphoric)