Persons sleeping less than 6 hours or more than 10 hours suffer from low-grade inflammation more often than persons sleeping 7-8 hours per night. This was observed in a University of Eastern Finland study focusing on the health and lifestyle habits among middle-aged men.
"Earlier studies have found a relation between reduced sleep and low-grade inflammation," says Maria Luojus, MHSc, one of the study researchers.
Furthermore, low-grade inflammation occurs in overweight, depression and diabetes.
The study is the first to analyse the association between sleep duration and serum micronutrient concentrations in a large sample, and 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," Luojus says.
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 study 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 says.
In addition to, the study participants' age, cumulative smoking history, alcohol consumption, depressive symptoms, physical activity and metabolic syndrome were taken into account in the data analysis.
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