2.1. Participants
Fifteen healthy (mean ± standard error of the mean [SEM]), normal-weight (BMI: 23.3 ± 0.4 kg/mAll participants had a regular sleep–wake cycle during the last four weeks before the experiments, with a minimum of 7 h sleep per night. The study protocol was approved by the ethics committee on research, involving humans at the University of Luebeck (Approval code 10-109), in accordance with the Declaration of Helsinki. All participants gave written informed consent before participation.