Fig. 1. Study protocol.
Depicted is the 19-day in-hospital protocol of the experimental sleep disturbance (ESD) model. Gray shading indicates sleep opportunity. Light blue shading indicates induced wakefulness under dim light conditions. After 3 nights of 8 h baseline sleep, participants were exposed to 3 cycles of ESD, each consisting of 3 nights of disturbed sleep (later sleep onset, hourly awakenings, earlier sleep offset, total sleep opportunity 4 hours) followed by 1 night of undisturbed sleep. The protocol ended with 3 additional nights of 8 h recovery sleep. Blood was drawn at two days during baseline and then every second day throughout the protocol. The present study includes samples collected at baseline (day 3), during the 3rd ESD cycle (day 14), after 1 night of recovery sleep (day 16), and after 3 nights of recovery sleep (day 18). During the control condition, participants had a sleep opportunity of 8 hours per night throughout the entire protocol.