ANAHEIM (California), Nov 14: Near the dawn’s early light is the most dangerous hour for women hospitalized with terminal heart failure, while men tend to die then as well as at the hour before midnight, according to a new study.

The study involved 308 men and 200 women aged 14 to 93 with congestive heart failure, flabby weakened hearts that are among the most common reason for hospitalization among the elderly.

All patients in the Brazilian trial received standard treatment, including bed rest, special diets and medicines to control high blood pressure and chest pain.

Researchers, headed by Dr Jose Fabri Jr. of Brazil’s Heart Institute, found that women were most at risk near daybreak while men were most likely to die between 5 am and 6:59 am as well as between 11 pm and 11:59 pm.

“Gender differences were unexpected,” Fabri said on Tuesday during his presentation at the annual scientific sessions of the American Heart Association.

He speculated that differing hormones and hormone patterns among the sexes may affect sleeping and waking patterns known as the circadian rhythm, and thereby account for their varying times of death.

Such hormone differences might also explain why heart failure is usually more severe in men than women, the Brazilian researcher said.

Earlier studies on less-seriously ill heart patients who were not hospitalized found that heart attacks and sudden death were most common during the first few hours after waking.

That might be because heart rate and blood pressure, as well as blood levels of chemicals that make arteries contract, tend to peak between 7 am and noon and put maximum stress on the heart.—Reuters