Push up those Zs

At last I have justification for a sleep-in! I've just read in a newspaper (Daily Mail, Tuesday 24 June 2008) a report of a piece of research that says that men who regularly sleep for 9 or more hours a night are less likely to get prostate cancer than men who sleep less than this. If you, or your husband/partner, is someone who likes a bit of a lie in, this couldn't be better news.

The research, which comes from Japan, is a fairly small study, which limits its value. It doesn't provide any answers to why there is this link between longer hours of sleep and a lower risk of prostate cancer. But it is interesting.

The researchers suggest that the link may have something to do with the hormone melatonin. Melatonin helps to regulate our wake-sleep cycles and is involved in the regulation of a number of body functions, including the immune system. It is also believed to suppress tumour growth. 

For sometime now researchers have suggested that night-shift workers and those from Western '24-hour' societies, who are exposed to high levels of artificial light at night when they should be asleep, are at more risk of breast cancer, because they secrete lower levels of melatonin. It seems that this may also have an impact on prostate cancer risk.

Melatonin is just one possible small factor in the complex issue that is cancer development. Not everyone who works nights gets breast or prostate cancer, just as not everyone who smokes gets lung cancer (and we know far more about smoking as a cause of cancer). But I will certainly enjoy a lie in with a much clearer conscience in future.