Does poor sleep increase your risk of developing cancer? Ample research suggests sleep quality post diagnosis does effect recovery rates.
A detailed Chinese study of 853 ovarian cancer patients concluded that longer sleep supported higher survival rates. Shorter and later sleep leading to much poorer outcomes. Conversely other research has suggested that routinely getting more than 9 hours sleep a night may adversely impact breast cancer survival rates.
There is very limited research examining the link pre-diagnosis – are those with long term poor sleep more likely to be diagnosed with cancer and if so are they more susceptible to certain forms of cancer?
Sleep in general is under researched. But it’s clearly essential to good health through mechanisms such as hormone regulation and soft tissue repair. It would seem entirely intuitive that this general support to good health would extend to offering some protection against some cancers. But does it?
The bulk of the available research focuses on insomnia amongst patients who have already been diagnosed with cancer. The argument is that a cancer diagnosis will, understandably lead to poor sleep. Our interest is the reverse of this. Can poor sleep actually cause cancer.
One recent large scale meta study by T.Shi et al suggests that there is a link between insomnia and cancer. The studies identified an increased cancer risk of 24% for insomnia suffers with the risk being greatest for women and most pronounced for the development of thyroid cancer. Shi though believes that the evidence supports the argument that insomnia is an early warning sign for cancer rather than an independent cause of the disease.
The studies available tend to focus on those with clinical level insomnia. Frequently these individuals will have a range of other health challenges. Whether the insomnia causes the health challenges or vice versa is a moot point.
Our focus at Sleep Better is very much on those who have sub- insomniac poor sleep. Just as it is worth dieticians focusing on the pre-diabetics we believe that significant health benefits can be gained by addressing sleep that is just a bit below where it should be but not full blown insomnia. We are convinced that, at least in the UK, a significant percentage of the adult population fall within this category. Sleep duration and quality are widely reported to have fallen consistently in the developed world over the last 80 years. Cancer rates have risen over the same period. Are the two directly connected or just both symptoms of a wider malaise amongst the developed world population.
The extent to which poor sleep directly causes cancer may be open to debate. What seems certain though is that good sleep is very unlikely to increase your cancer risk. So addressing any sub optimal sleep really is a one way bet when it comes to cancer. It will either do nothing or reduce your risk. And whatever else improving your sleep may do it will certainly make you feel better and more alive
Given the paucity of evidence we would suggest that examining a causal link between both clinical insomnia and sub-optimal sleep and various cancers could be a future research priority.