A new study says that people who sleep less than 6 hours a night appear to be more likely to have risk factors for diabetes, heart disease, and strokes; including high blood sugar levels, high blood cholesterol levels, and carrying a lot of weight around the midsection. This combination of risk factors, along with high blood pressure and high blood levels of fats, is known as metabolic syndrome.
The study, conducted at Yonsei University in South Korea, followed 2,600 people for more than 2 years, drawing data from two surveys where people were asked about their lifestyles. The surveys included questions about the sleep habits of the participants. The surveys were administered twice, once between 2005 and 2008 and again between 2008 and 2011. The participants also underwent medical exams and shared data from their medical histories.
After an average follow-up of 2.6 years, 22% of the participants (about 560 people) developed metabolic syndrome. The researchers found that the participants who did not get at least 6 hours of sleep a night were 41% more likely to develop metabolic syndrome than those who got 6 to 8 hours of sleep a night. Sleeping less was linked to about 30% increased risk of high blood sugar and excess belly fat, as well as 56% higher odds of hypertension, compared to those who slept longer.
"The 'short' sleepers should be aware of the risks of developing metabolic syndrome, which could lead them to suffer from life threatening and chronic diseases," lead author Dr. Jang Young Kim of Yonsei University in South Korea told Reuters Health in an email.
These findings are consistent with other studies that have found an association between sleep duration, cardiovascular disease, and metabolic syndrome.
One limitation of the study that it relied on participants to accurately recall their sleep habits, medical conditions, and lifestyle behaviors. It also did not collect data on the quality of sleep.
The study was published in the journal Sleep.