Working hours, sleep duration and the risk of acute coronary heart disease: a case-control study of middle-aged men in Taiwan.

Background: This study aimed to examine whether long working hours and short sleep duration were associated with an increased risk of acute myocardial infarction (AMI) or severe coronary heart diseases (SCHD), independent of established psychosocial work-related factors.
Methods: A case-control study was conducted. Cases were 322 men, aged <60 years and economically active, who were admitted to hospital with a first diagnosed AMI or SCHD during 2008-2011, of whom 134 were confirmed AMI and the other 188 were angiography-confirmed SCHD. Controls were 644 men who were drawn from a national survey and were matched to the cases on age, education and area of residence. Odds ratios of total CHD and confirmed AMI in relation to average weekly working hours and daily hours of sleep were calculated.
Results: Men with average working hours longer than 60 h/week were found to have significantly increased risks for total CHD (OR=2.2) as compared to those with weekly working hours in 40-48 h, and those with daily hours of sleep fewer than 6 h were found to have increased risks for CHD (OR=3.0) as compared to those with sleeping hours in 6-9 h. Restriction to confirmed AMI yielded a greater risk and these associations remained consistent with adjustment of smoking status, body mass index and psychosocial work factors including job demands, job control, workplace justice, job insecurity and shift work.
Conclusion: The results support the hypothesis that long working hours and short sleep duration contribute independently to the risk of cardiovascular diseases in men.
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