Study finds that longer sleep duration and sleep disturbances are associated with increases in markers of inflammation.

Inflammation is a hot topic these days, as it contributes to numerous health concerns. A new study in the journal Biological Psychiatry reports that inflammatory markers were found in people who have sleep disturbance issues as well as long sleep duration. This highlights the fact that both too little and too much sleep may cause inflammation. This is concerning, in that inflammation contributes to depressive symptoms, as well as a myriad of other health issues. For some time now, The Centers for Disease Control and Prevention (CDC) has stated that insufficient sleep is a public health epidemic. Insomnia and other sleep disorders have previously been found to be linked to increased risk of inflammatory disease and mortality.

Substances such as C-reactive protein (CRP) and interleukin-6 (IL-6) increase in response to inflammation, circulate in the blood stream and are predictors of health issues such as hypertension, cardiovascular issues, and type 2 diabetes. Although there have been numerous studies that have explored the mechanisms that link immunity with sleep health, the variations amongst the studies have made it difficult to get to the bottom of the true effects.

A systemic review of existing studies was performed by Michael Irwin, Richard Olmstead and Judith Carroll of the Cousins Center for Psychoneuroimmunology at UCLA Semel Institute for Neuroscience, with the intention of finding the links between sleep and inflammatory markers. They researched 72 individual articles, including over 50, 000 individuals from clinical and population-based studies. CRP, IL-6, and tumor necrosis factor α (TNFα) were studied as indicators of inflammation.

7-8 hours of sleep per night is considered a normal sleep duration. The researchers found that sleep disturbance (not sleeping well or suffering from insomnia) as well as too much sleep (exceeding 8 hours) were associated with increased levels of CRP and IL-6. A shorter sleep duration, of less than 7 hours per night, was associated with increased levels of CRP. No associations were observed with TNFα.

Michael Irwin, one of the researchers, stated insomnia and sleep disturbances should be viewed as risk factors for inflammation, along the same lines as sedentary behavior or an unhealthy diet are. Sleep behavior treatments could be a way to resolve the inflammation and to reduce the risk of subsequent diseases.

Sleep Disturbance, Sleep Duration, and Inflammation: A Systematic Review and Meta-Analysis of Cohort Studies and Experimental Sleep Deprivation," by Michael R. Irwin, Richard Olmstead, and Judith E. Carroll (doi: 10.1016/j.biopsych.2015.05.014). It appears in Biological Psychiatry, volume 80, issue 1 (2016), published by Elsevier.