The study, conducted by researchers from several universities and hospitals in the western Japanese city of Kyoto, revealed a link between wake-up times and a person's cardiovascular condition.
"Rising early to go to work or exercise might not be beneficial to health, but rather a risk for vascular diseases," said an abstract of the study.
The study, covering 3,017 healthy adults aged between 23 through 90, found that early risers had a greater risk of heart conditions including hypertension and of having strokes.
However, the study also noted that early risers were usually older.
The study is being presented this week at the World Congress of the World Federation of Sleep Research and Sleep Medicine Societies, being held in Cairns, Australia.
A separate study released in June by researchers at the University of Pennsylvania found that chronic sleep deprivation adds stress to the heart, putting a person at greater risk of cardiovascular disease and death.