Connection Between Fragmented Sleep and Tumor Growth?

A study funded by the National Institutes of Health (NIH) is the first to show (in an animal model) how fragmented sleep directly impacts tumor growth and aggressiveness. The study titled “Fragmented sleep accelerates tumor growth and progression through recruitment of tumor-associated macrophages and TLR4 signaling” appeared in Cancer Research. According to a summary of the study, sleep-deprived mice given the same cancer-inducing treatment developed larger, more aggressive tumors than well-rested mice.

Click here to view abstract

The research team also reports how they found the immune system of the sleep-disrupted mice was less effective at fighting the early stages of cancer than the immune system of the well-rested mice. “It’s not the tumor, it’s the immune system. said Study director Professor David Gozal in Medical News Today. “Fragmented sleep changes how the immune system deals with cancer in ways that make the disease more aggressive. Fortunately, our study also points to a potential drug target.”

Specifically, he says, they found a biological messenger—the protein TLR4—which helps to activate the innate immune system. Gozal says TLR4 seems to act as a ‘lynchpin’ between sleep loss and cancer promotion.

MNT reports that the study came about because research linking sleep apnea and death from cancer caught the attention of Prof. Gozal, an authority on the consequences of sleep apnea, and its hallmark, disrupted sleep.
In 2012, researchers reported two studies that found a strong link between sleep apnea and cancer mortality.

Prof. Gozal explains that, usually in muscle, tumors become encased in a tissue capsule rather like a scar: they become “little spheres,” with a clear separation between cancerous and normal tissue. However, in the mice that had disrupted sleep, the tumors had pushed through the capsule and gone into the muscle and bone.

Source: American Association for Cancer Research

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