2.2. Study Design and Procedure
sleep loss
Participants were tested in a randomized, balanced, crossover design on three conditions spaced at least three and at maximum five weeks apart. Hormonal orexigenic/anorexigenic balance, subjective feelings of hunger and appetite, general desire for food, as well for savory and sweet foods, were assessed after (i) one night with 4 h of sleep during the first half of the night (‘late-night sleep loss’; bedtime: 22:30 h to 03:00 h), (ii) one night with 4 h of sleep during the second half of the night (‘early-night sleep loss’; bedtime: 02:15 h to 06:45 h), and (iii) one night with regular 8h of sleep (‘regular sleep’; bedtime: 22:15 h to 06:45 h).For each experimental session, participants attended the research unit at 19:15 h and received a standardized light dinner (380 kcal) at 20:15 h. Thereafter, they were allowed to drink only water (max. 250 mL) until the following day. Participants were then prepared for polysomnographic recordings, and electrodes (C3, C4 derivations) were placed above, below, and beside the eyes for horizontal and vertical electrooculogram. For electromyogram, two electrodes were attached to the chin. Polysomnographic recordings were performed using a Nihon Kohden amplifier (EEG 4400 series, Nihon Kohden GmbH, Rosbach Vor Der Höhe, Germany). Data were scored offline according to standard criteria (for details, see [