The study, conducted by researchers from several universities and hospitals in the western Japanese city of Kyoto, examined 3,017 healthy adults between the ages of 23 and 90.
It found that individuals who usually rose before 5 a.m. had a 1.7 times greater risk of high blood pressure that the late risers. Also the early birds were twice as likely to develop hardening of the arteries compared to those who got up two to three hours later.
Bloomberg quotes Mayuko Kadono, a physician at Kyoto Prefectural University of Medicine, who led the study as saying, "The results are contrary to the commonly held belief that early birds are in better health."
"We need to find what the causes of this are, and whether exercising after waking early is beneficial,'' he added.
Establishing a possible link between wake-up times and a person's cardiovascular condition, the study also found that early risers had a greater risk of heart conditions including hypertension and strokes.
"Rising early to go to work or exercise might not be beneficial to health, but rather a risk for vascular diseases," the study abstract said.
The study is being presented this week (Sep 2- Sep 6) 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 also revealed that chronic sleep deprivation adds stress to the heart, making him more prone to cardiovascular problems.
