0041 Circadian Misalignment Increases The Desire For Food Intake In Chronic Shift Workers

Abstract

elucidated. We therefore examined circulating FFA, glucose and insulin during an inpatient simulated night shiftwork protocol. Methods: 14 healthy adults (6M; aged 26.4 ± 1.2y, BMI 22.7 ± 0.5 kg/m 2 ; mean±SD) participated in the study. Blood was sampled every 2 hours for 24 hours during circadian alignment and circadian misalignment and every 30 minutes after each meal for 2 hours. Blood was assayed for FFA, insulin and glucose. Participants were provided with a 3-day energy balance diet prior to study admission and the diet was continued inpatient. Diet was designed with the same meals each day. Results: Circadian misalignment was induced by our simulated nightshift work protocol, as evidenced by the melatonin rhythm which did not adapt to the nightshift schedule. Mean FFA levels were significantly elevated during wake (+41 ± 18%, p<0.05; results are mean±SEM), sleep (+35 ± 10%, p<0.01) and across 24h (+35 ± 15%, p<0.01) during circadian misalignment. Furthermore, we found elevations in 24h mean glucose (+7 ± 3%, p<0.05) and mean glucose in response to breakfast (+24 ± 6%, p<0.01) during circadian mis-alignment as compared to baseline, without a compensatory increase in insulin. Conclusion: Acute circadian misalignment results in elevated 24h FFA and glucose concentrations, as well as an increased glucose in response to the first meal of the day. Sustained chronically, these disturbances may increase the risk for developing type 2 diabetes. Introduction: Shift workers face increased risk of obesity and frequently experience misalignment between their circadian system and behavioral/environmental cycles. While emerging evidence suggested that such circadian misalignment can acutely disrupt energy homeo-stasis in healthy adults accustomed to a day schedule, little is known about its acute impact on chronic shift workers. Here we examined the effects of circadian misalignment on ratings of hunger and appetite, the hunger hormone ghrelin, and energy expenditure in chronic shift workers. Methods: Seven healthy chronic shift workers (mean ± SD, age 37 ± 7 y, BMI 24.4 ± 3.2 kg/m 2 , 3 men) each underwent two highly controlled 3-day laboratory visits in a randomized cross-over design: a circadian alignment protocol and circadian misalignment protocol (12-h inverted behavioral and environmental cycles). Participants consumed an isocaloric diet per 24 h. Identical test meals were given 1h and 13 h following scheduled wake time. Energy expenditure was derived from indirect calorimetry measurements for these test meals sessions. Hourly active ghrelin concentrations and self-rating of hunger and appetite were assessed. Daily locomotor activity was recorded by actiwatch. Results: Circadian misalignment led to a ~17% increase in 24-h active ghrelin levels in the chronic shift workers (P<0.05). Consistently, they