Paradoxical post-exercise responses of acylated ghrelin and leptin during a simulated night shift

Approximately 10% of employees undertake night work, which is a significant predictor of weight gain, possibly because responses to activity and eating are altered at night. It is known that the appetite-related hormone, acylated ghrelin, is suppressed after an acute bout of exercise during the day, but no researcher has explored whether evening exercise alters acylated ghrelin and other appetite-related outcomes during a subsequent night shift. Six healthy men (mean ± SD: age 30 ± 8 yrs, body mass index 23.1 ± 1.1 kg/m2) completed two crossover trials (control and exercise) in random order. Participants fasted from 10:00 h, consumed a test meal at 18:00 h, and then cycled at 50% peak oxygen uptake or rested between 19:00–20:00 h. Participants then completed light activities during a simulated night shift which ended at 05:00 h. Two small isocaloric meals were consumed at 22:00 and 02:00 h. Venous blood samples were drawn via cannulation at 1 h intervals between 19:00–05:00 h for the determination of acylated ghrelin, leptin, insulin, glucose, triglyceride, and non-esterified fatty acids concentrations. Perceived hunger and wrist actimetry were also recorded. During the simulated night shift, mean ± SD acylated ghrelin concentration was 86.5 ± 40.8 pg/ml following exercise compared with 71.7 ± 37.7 pg/ml without prior exercise (p = 0.015). Throughout the night shift, leptin concentration was 263 ± 242 pg/ml following exercise compared with 187 ± 221 pg/ml without prior exercise (p = 0.017). Mean levels of insulin, triglyceride, non-esterified fatty acids, and wrist actimetry level were also higher during the night shift that followed exercise (p