Middle-aged men who sleep less than six hours or more than 10 hours suffer from low-grade inflammation more often than men sleeping seven-eight hours per night, finds a new study.
Furthermore, low-grade inflammation occurs more in people who are overweight, depressed and have diabetes.
The study is the first to analyse the association between sleep duration and serum micronutrient concentrations.
It found a link between high serum copper concentration and long sleep duration. Serum micronutrient concentrations are affected by many factors, including an individual's general health and diet.
"Based on this study, however, it is impossible to say whether sleeping long results in high serum copper concentrations or vice versa," said Maria Luojus, one of the study researchers from University of Eastern Finland.
It has been suggested that high serum copper concentration associates with pro-oxidative stress.
Pro-oxidative stress is found in many chronic diseases, such as coronary artery disease.
"Nevertheless, when the participants' cardiovascular diseases were taken account for, our results remained unchanged. The association between serum copper concentration and sleep duration persisted independently of cardiovascular diseases," Luojus explained.
The study involved 2,682 men living in Eastern Finland.