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Introduction: Quick return (<11h between shifts, QRs) have been common in Swedish Healthcare. Previous research has shown an association between QRs and increased risk for sick leave. The mechanisms driving this association could be related to short sleep as sleep length is reduced by ~1 hour in relation to quick returns. Short sleep could alter the activation of the hypothalamic-pituitary-adrenal (HPA)-axis, increase inflammation and increase risk for metabolic diseases. The aim of the study was to explore the acute effects of a quick return on blood markers for stress, inflammation and metabolism.

Methods: Newly graduated nurses were recruited via the introduction program for new nurses at one university hospital in Sweden. Of the 54 nurses recruited 24 participants completed participation. They were followed during two pre-scheduled work periods, with and without a quick return. The order of the two conditions was randomized across participants. The participants left blood samples in the morning (fasting) and afternoon of the second day in both conditions; “evening-day-day” versus “day-day-day.” Both conditions were preceded by a day off work. Food intake was standardized during sampling days. Blood samples were analyzed for creatinine, glucose, erythropoietin and cortisol using ELISA kits. Further analysis from U-PLEX Custom Metabolic Group 1 V-PLEX Custom Human Biomarkers 1 are ongoing and will be presented at the conference. The data were analyzed with an ANOVA examining the effects of the conditions, time of day, and interaction effects between conditions and time of day (18 participants had complete blood samples at both conditions).

Results: There was a significant effect of condition on creatinine (F=5.04; p < 0.05; df=1,17) and cortisol (F=9.58, p < 0.01; df=1,17) which were higher both in the morning and in the afternoon after a quick return. There were no significant effects of condition on CRP (F=0.32; p>0.05; df=1,17), erythropoietin (F=0.02; p>0.05; df=1,17) or glucose (F=1.26; p>0.05; df=1,17). None of the outcome measures showed a significant effect on condition and time of day.

Conclusion: The results indicate that an acute effect of a quick return is increased activation of the HPA-axis with higher levels of cortisol throughout the day. This increase was not mirrored by changes in glucose, erythropoietin or inflammatory levels. While this study indicates that quick returns leads to an acute (and probably functional) stress response, future studies should determine in what circumstances this stress may be harmful. Support: FORTE- Swedish Research Council for Health, Working Life and Welfare (2017–02032), Sweden.