In 1985, the Whitehall II cohort study began collecting data on 10,308 participants employed in the London offices of the British civil service. Over 35 years later, research on this data set finds that sleeping less than 5 hours per night is linked to a higher risk of multiple diseases.
Past studies have linked low amounts of sleep to individual chronic diseases including obesity, diabetes, and cardiovascular diseases. The results from this study benchmark the first time that researchers have documented the link between low sleep and multimorbidity, or multiple chronic diseases.
The researchers’ analysis suggests that short sleep duration at age 50 is associated with a 20% increase in the risk of a single chronic disease and an increased risk of developing subsequent chronic diseases. The researchers did not observe an increase in mortality in the study cohort, but this may be due to the timeframe of the study data.
Sleep plays an essential role in health and a multitude of physiological functions. Though the link between low sleep duration and chronic disease is not completely understood, these results come as no surprise to health officials.
Jo Whitmore, senior cardiac nurse at the British Heart Foundation, says that “getting enough sleep allows your body to rest. There are a host of other ways that poor sleep could increase the risk of heart disease or stroke, including by increasing inflammation and increasing blood pressure.”
Current guidelines recommend that older adults sleep for 7 to 8 hours per night. Lead study author Dr. Severine Sabia adds that “sleep durations above or below this have previously been associated with individual chronic diseases.”
Data from the Whitehall II study has been used in a number of other landmark studies. Other research groups have used this cohort data to associate employment grade with the risk of coronary heart disease and how social aspects of work are associated with health.