Daily variation in CSF concentrations of cortisol (top) and hypocretin-1 (middle) as well as locomotor activity (bottom). Data from experiments 1 (solid line) and 2 (circle) are shown as average ± SEM. A dashed line connects the control time point with a sample taken at the same time, but after 5 hr of wake extension or daytime control in experiment 2. Arrows indicate time of CSF sampling. An axis break is placed at the top to allow for viewing of all data without compression of the y-axis. Activity data are binned in 30 min intervals. Times of scheduled darkness are shown as dark bars along the x-axis. All data from experiment 1 are double-plotted along the x-axis.