Although it may be lunacy to think that more people die of cardiac arrest when the moon is full, the darkness of the new moon could somehow be safer for the heart.
In cardiac arrest -- which is different from a heart attack -- the heart stops beating, perhaps due to an electrical or rhythm disturbance. Victims die if their heart is not re-started within minutes with a properly timed electric shock.
Researchers analyzed a database of over 2.3 million emergency visits in seven northern New Jersey emergency departments and factored in lunar cycles during the 4,000-day period of the study.
They didn't find any correlation whatsoever with full moon, but did find a decrease of 6.5% in incidence of cardiac arrest during new moons.
Annual Meeting of the American College of Emergency Physicians Chicago, IL October 16, 2001
Not sure of the mechanism here but it seems to be an interesting observation.