So if I workout every day, some days do strength training others long runs, cardio, sprints, strides my heart falure risk is higher with the usage of melatonin pills?

Also in the article it mentions that they focus only on groups that have already been prescribed the medication or have diagnosed insomnia or other heart related issues so if you are fully healthy and take it from time to time to recover sleep or change a timezone(when travelling) it might be okay for single time use(I am not a doctor).