From a medical website:
April 27, 2011 -- The most common time of day for heart attacks is the morning, and now new research suggests that morning heart attacks are also the most serious. Heart attacks occurring between 6 a.m. and noon were associated with the most the damage in the study, reported Wednesday in the journal Heart.Apr 27, 2011
Risk Factors: Hypertension
Heart Attacks in the Morning Are More Severe - WebMD
From a News website:
Heart attacks are five to six times more likely to occur in the early morning hours between 1 and 5 a.m., and studies have shown that morning heart attacks tend to be more severe than those that happen later in the day.Feb 28, 2012
Heart attacks more common in the morning | Fox News
So people have to decide between the two, 6 AM to noon per the medical site,
Or:
1am-5am per the news site?
Take a pick there are likely a half a dozen other reports claiming this or claiming that, and you will never get a real answer because both answers will no doubt be backed up by serious studies.
People need to not worry so much about stuff, if you are happy being a morning person, then be happy being a morning person. If you enjoy being a night person enjoy being a night person.
Learn you own personal circadian rhythm, and either live with it, or fret over it, because you do not want to live the rhythm you were dealt.
Thanks for the comment, it is useful for the community.