Intervention on coronary risk factors by adapting a shift work schedule to biologic rhythmicity

The effects of a new shift rotation schedule on coronary risk factors was assessed in a short-term intervention trial in 45 volunteer policemen that were divided into two groups. They worked 4 weeks each on their customary schedule (counter-clockwise rotation) and on the new schedule (clockwise rotation). Serum lipids, glucose, uric acid, blood pressure, nocturnal urinary excretion of catecholamines, the quality and quantity of sleep, and tobacco consumption were assessed before, during, and after each schedule. During clockwise rotation, serum levels of triglycerides (but not cholesterol), and of glucose (but not uric acid) were significantly lower than during counter-clockwise rotation. Sleep was reported to be longer and better with clockwise rotation, but tobacco consumption did not differ between the two schedules. After clockwise rotation, systolic (but not diastolic) blood pressure and urinary excretion of catecholamines were significantly lower than after counter-clockwise shift rotations. The results suggest that adapting shift rotation to biological circadian rhythms has a favorable short-term effect, not only on subjective well being but also on risk factors for ischemic heart disease.