Sleep fragmentation and cancer

Some studies have linked obstructive sleep apnea (OSA) to cancer. This study shows that sleep fragmentation in mice was associated with larger, more aggressive tumors than mice that did not have sleep fragmentation. Since I don't have access to the full article, it's unclear how the sleep fragmentation was produced. Also, OSA can cause sleep fragmentation but also low oxygen levels, and low oxygen could be linked to tumors. Either way, it's thought that OSA causes a systemic inflammatory response, and this may be what is linked to cancer.

Obstructive Sleep Apnea and Cancer

At the American Thoracic Society 2011 meeting in Denver, researchers presented interesting results about cancer in mice with experimentally induced obstructive sleep apnea (OSA).

In OSA, patients can have repetitive, brief episodes of low oxygen levels called hypoxia. Persistent, prolonged hypoxemia, as opposed to the repetitve type seen in OSA, has been shown to promote growth of cancer cells. But no study had demonstrated that the intermittent hypoxia in OSA could do this.

Researchers injected melanoma cells in mice. They exposed one half to normal oxygen levels for six hours, and the other half to 20 seconds of hypoxia, 60 times per hour for six hours to mimick what might occur in OSA. The results showed that the melanoma cells proliferated faster in those mice with hypoxia when compared to the mice that were exposed to normal oxygen levels.

This study involves two extremes - normal vs very abnormal, since experiencing 60 episodes of hypoxia per hour for 6 hours would be very severe OSA. We do not know if more mild amounts of hypoxia will also promote tumor growth - more studies will be needed to sort that out.