Increased risk of heart disease in young shiftworkers

YOUNG male shiftworkers may be at increased risk of cardiovascular disease later in life due to prolonged high levels of cortisol and increased BMI, a small study suggests.

Dutch researchers studied hair samples taken from 33 men working shifts at a textile factory and 89 controls who only worked in the day and measured long-term (three months) cortisol levels, thought to be a marker of chronic stress. They also calculated the men’s BMI. 

Long-term elevated cortisol levels were significantly higher in the shiftworkers aged under 40 years compared with daytime-only workers of the same age (48.53 vs 26.42 pg/mg hair).

But there was no such link in the older men, whose cortisol levels were similar regardless of work pattern.

“This contrasts with the general hypothesis that the tolerance to shiftwork decreases with age,” the researchers wrote, adding that older men may grow accustomed to altered rhythms of cortisol secretion brought on by shiftwork.

Younger shiftworkers, but not older ones, also had higher BMI than the daytime workers (27.2 vs 23.7) and the higher the BMI, the higher the cortisol level.

“Long-term elevated cortisol levels and obesity at younger age can contribute significantly to increased cardiovascular risk at older age,” the researchers wrote, adding more research was needed to unravel the role of cortisol in shiftworker health.

J Clin Endocr Metab 2011, in press