Is Your Job Making You Sick?

Back in 2007 I was surprised to see that the International Agency for Research on Cancer (a United Nations agency) had listed shift work as a suspected cancer causing factor. The reason for this was the belief that shift work disrupted normal hormonal circadian rhythms.  It has also been noted that people with jobs requiring shift work have higher rates of obesity, diabetes and cardiovascular disease.

A new publication by Frank Scheer and colleagues has examined the specific hormonal changes that occur when sleep-wake patterns are displaced and their affects on blood glucose, blood pressure, and appetite.

They found that displacing the normal sleep-wake cycle altered the normal secretion of cortisol and leptin and that the displacement was proportional to the degree of displaced sleep.  The displaced pattern of cortisol secretion led to significant hyperglycemia increasing the risk of diabetes.  In some cases the hyperglycemia following sleep displacement was high enough to be classified as prediabetic and in one case as diabetic.  These values were found in individuals who had normal blood glucose levels without sleep disruption.

Decreases in leptin secretion were also noted and this is associated with an increase in appetite, increasing the risk of obesity.   Blood pressure also rose although the hormonal cause of this rise was not clear.

For details see: Scheer FAJL, and others. 2009.  Adverse metabolic and cardiovascular consequences of circadian misalignment. Proceedings of the National Academy of Sciences in the USA. Vol 10. 1073 (PNAS early edition: March 10)