"Siesta" is a Spanish word that comes from the Latin phrase "hora sexton" — or "sixth hour" — six hours after dawn. That kind of afternoon nap was favored by Leonardo da Vinci, who slept two hours a night but took a 15-minute power nap every four hours.

He must have had a rare gene that allows brain restoration with short sleep — and he had the good sense to nap all day long for a smart length of time.  

A study from Brigham and Women's Hospital evaluated 3,000 people's napping habits and discovered that naps of 30 minutes or longer are associated with having a larger waist, being overweight, having heart disease, metabolic syndrome, and elevated glucose and blood pressure.

Other habits that make long naps even less healthy are eating a big lunch before snoozing, smoking, napping in a bed instead of a chair, and having unhealthy eating and sleep schedules (too late, too erratic).

But a power nap like Leonardo's of 15 minutes has no association with metabolic conditions or obesity, and it gives power nappers a lower systolic blood pressure than people who don't take siestas.

Tap into the art of healthy napping.

What will get from it? If you don't have cardiovascular disease, taking just one or two naps a week reduces your future risk of heart attack, heart failure, or stroke by 48% compared to people who never nap.