A new study published in the current issue
of Archives of Environmental & Occupational Health (vol. 64, No. 3) shows that this combination of night work, overtime
and shortened sleep can contribute to the development among police officers of the metabolic syndrome, a combination of unhealthful
factors that increase the risk of cardiovascular disease (CVD), primarily heart disease and stroke.
John M. Violanti, PhD, research associate
professor in UB's Department of Social and Preventive Medicine in the School of
Public Health and Health Professions, is first author on the paper, and received
significant contributions from biostatisticians in the CDC's National Institute for Occupational Safety and Health (NIOSH).
"These findings reinforce the scientific
value of studying the effects of occupation on cardiovascular risk factors," said Violanti. "This is especially important
in first responders, who are selected on initial good overall physical and mental health. Exploring specific job-related associations,
such as shift work, add to the benefit of such investigations."
The research is based on data from the
Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study, which has been ongoing since 2003. Metabolic syndrome is
defined as abnormalities in any three of five important clinical measures: abdominal obesity, triglycerides, high-density
lipoproteins (HDL), blood pressure and fasting glucose level.
This baseline study involved 98 police
officers who were selected randomly from a total of 934 officers. Clinic personnel in UB's Center for Preventive Medicine
obtained a fasting blood sample, and measured systolic and diastolic blood pressure and waist circumference, and participants
also completed an extensive questionnaire on demographics and lifestyles choices.
Researchers obtained day-by-day data on
shift-work and overtime hours from payroll records.
Results showed that overall, 30 percent
of officers working the night shift had metabolic syndrome, compared to 21 percent in the National Health and Nutritional
Examination Survey (NHANES III), which is based on data collected from the overall general
population.
However, officers in the night shift were
younger on average than those working the day shift -- 36.5 years vs. 42.6 years -- but despite their younger age, the percentage
with metabolic syndrome (30 percent) was higher than the 24-percent average for the 30-39 age group in the general population.
"This slightly higher prevalence at a younger
age coincides with police mortality cohort studies, which found a higher risk of CVD among
younger officers," said Violanti. "This finding is in contrast to that in the general population, in which CVD
risk increases with age.
"One potential explanation for this unusual
finding is that midnight-shift officers were most likely to be sleep deprived because of difficulties associated with day
sleeping. Sleep debt has been shown to have a harmful impact on carbohydrate metabolism and endocrine function, which could
contribute to metabolic disorders."
The percentages of several factors related
to risk of metabolic syndrome were higher in night-shift officers than in the general population, as well as in day and evening-shift
officers in the study:
• 55 percent had elevated waist
circumference, compared to 50 percent and 30 percent for women and men
• 50 percent had low HDL
cholesterol levels, compared to 38 percent and 35 percent in women and men, respectively.
• Hypertension and glucose intolerance,
an indication of diabetes, were more prevalent in night-shift officers.
In addition, officers who worked midnight shifts and had less than six hours sleep had a significantly higher average of metabolic-syndrome
components than those who worked day shifts.
"Information from this study could help
guide further investigation into health of first responders," Violanti said, "not only of police officers, but firefighters,
emergency medical technicians, nurses, physicians, air traffic controllers and the military.
"Results of this study, and possible future
prospective studies, may add to our existing knowledge of the associations between shift work and cardiovascular health in
high-risk occupations."
The research was supported by a grant to
Violanti from NIOSH.
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