A new study has found that less than six hours or more than 10 hours of sleep at night increases the risk of heart disease, stroke and type 2 diabetes.

Researchers from the Seoul National University College in South Korea found that too much or too little sleep both raised the risk of metabolic syndrome, a condition that has been associated with increased blood pressure, high blood sugar levels and obesity.

The findings, which were published in the journal BMC Public Health, showed that men who slept under six hours and those who slept more than 10 hours each night were more likely to develop metabolic syndrome, compared to those who slept for eight hours.

The research was based on data from the Health Examinees (HEXA) study, which analyzed the interaction of genetic and environmental factors in relation to chronic disease in South Korea.

The data from the HEXA study took into consideration the medical history, use of medication, modifying lifestyle factors and family medical history of 133,608 participants aged between 40 and 69.

According to Medical News Today, the participants were also asked to provide information on how much they slept each day, including night-time sleep and daytime naps.

The findings also suggested that a person's sex may be a factor in developing metabolic syndrome.

Men who slept for under six hours at night were more likely to have a higher waist circumference, while those who slept for more than 10 hours had raised triglyceride levels.

The study suggested that the health risks tied to excessive or lack of sleep were higher among women.

Apart from metabolic syndrome, women are also at risk of having high blood sugar, low HDL cholesterol and a higher waist circumference, which is a sign of excessive belly fat.

"We observed a potential gender difference between sleep duration and metabolic syndrome, with an association between metabolic syndrome and long sleep in women and metabolic syndrome and short sleep in men," said Claire E. Kim, lead author of the study, according to Newsweek.

Thirteen percent of women and 11 percent of men who participated in the study had slept too little. Only 1.7 percent of women and 1.5 percent of men said they slept for more than 10 hours a day.

The research did not analyze how sleep patterns affect the development of metabolic syndrome, but the authors suggested that sleep duration could be a factor in the production of hormones that regulate appetite as well as the production and consumption of energy in the human body.