Cortisol,

one of the main chemicals released during fight or
flight, has a very corrosive effect on the soft muscle tissue
like the heart, lungs and intestines. It is also thought to playa
part in inadvertently killing brain cells. So if we have
physiological fight or flight (the release of stress hormones)
but no behavioural fight or flight (those same stress
hormones are not used and stay in the blood, like tissue
assassins), we are killing ourselves from the inside out. The
body realises this and will find any surrogate release it can
for these trapped hormones, usually in a displaced manner,
for example road rage, marital disputes, temper tantrums,
irrational behaviour, even violence. These incidents do
release the trapped hormones but, due to the contentious
nature of the release, they create more and we find ourselves
locked into a cycle of stress degeneration.