I don’t know about this one. If someone is taking melatonin long term they probably suffer from insomnia. Sleep deprivation seems to be a more likely killer to me.
On asking AI if melatonin has heart protection benefits:
Yes, emerging research suggests that melatonin may offer significant cardioprotective benefits, primarily through its potent antioxidant, anti-inflammatory, and anti-apoptotic properties.[1][2] These mechanisms contribute to its potential role in mitigating various cardiovascular diseases, including ischemia-reperfusion injury, hypertension, and atherosclerosis.