Too much or too little sleep may up inflammatory disease risk

Sleep disturbances and longer sleep duration are associated with increases in markers of inflammation, finds a new study.

Insufficient sleep is considered a public health epidemic by the US Centers for Disease Control and Prevention. 

"Together with diet and physical activity, sleep health represents a third component in the promotion of health-span," said Michael Irwin from the University of California - Los Angeles, US.

Common sleep disturbances, such as insomnia, have been associated with increased risk of inflammatory disease and mortality.

"Sleep disturbance or insomnia should be regarded as behavioural risk factors for inflammation, similar to the adverse effects of high fat diet or sedentary behaviour," Irwin added. 

Inflammation causes a number of substances to increase in volume in the blood stream, including C-reactive protein (CRP) and interleukin-6 (IL-6). 

Increased levels of these substances predict adverse health conditions including cardiovascular events, hypertension and Type 2 diabetes, said the paper published in the journal Biological Psychiatry.

People with a normal sleep duration get 7-8 hours of shut-eye per night. 

The findings showed that sleep disturbance -- poor sleep quality or complaints of insomnia, and long sleep duration which is more than 8 hours -- were associated with increased levels of CRP and IL-6. 

Shorter sleep duration was associated with increased levels of CRP. 

"It is important to highlight both too much and too little sleep appears to be associated with inflammation, a process that contributes to depression as well as many medical illnesses," noted John Krystal, editor of the journal Biological Psychiatry.

For the study, the team conducted a meta-analysis of 72 different articles for associations between sleep and inflammatory markers, which included over 50,000 participants from population-based and clinical studies. 

Treatments targeting sleep behaviour could be a strategy for reversing the inflammation and reducing risk of inflammatory illnesses, the researchers concluded.