Disruption in Circadian Rhythm Increases Cardiovascular Disease Risk Factors in Shift Working Nurses

Background Shift work is associated with behavioral, psychosocial, and physiological consequences in the body that may cause cardiovascular disease (CVD) risk. Therefore, in this study we tried to demonstrate the disruption in circadian rhythm of blood pressure by ambulatory blood pressure monitor in shift working nurses. Methods A total of 50 nurses, 25 night shift working nurses (NSWN), and 25 day shift working nurses (DSWN) underwent ambulatory blood pressure monitoring (ABPM) for a period of 24 hours. Along with measurements of inflammatory markers (hs-CRP and IL-6) the risk factors for cardiovascular disease between NSWN and DSWN and their possible relationship with disrupted circadian rhythm were measured by circadian rhythm questionnaire. Results The mean systolic and diastolic pressure for a period of 24 hours and mean diastolic blood pressure analysis throughout the sleep time was found greater in the NSWN than the DSWN (118 mm Hg vs. 112 mm Hg, p < 0.05: 72 mm Hg vs. 68 mm Hg, p < 0.05: 62 mm Hg vs. 59 mm Hg, p < 0.05). High mean blood pressure readings were found to be more frequent in the NSWN (p < 0.05) than in DSWN. No significant differences were found in IL-6 and hs-CRP levels. However, a significant difference in circadian rhythm abnormality was found in NSWN than in DSWN. Conclusion The 7 day/24 hours ambulatory blood pressure monitoring (ABPM) in NSWN showed a reduced circadian rhythm variation in blood pressure along with abnormality in circadian rhythm itself as compared with DSWN. Work schedules and the consequent rest–activity schedules affect circadian rhythms, with likely long-term impact on health. Therefore, working in critical care unit during night hours leads to abnormal blood pressure in NSWN, suggesting that this type of work, in which sleep is disturbed, leading to mental stress, could be a direct risk factor in cardiovascular diseases.