Figure 1.

Experimental procedure of experiment 1 (acute metyrapone [MET]) and experiment 2 (chronic MET). White rectangles represent light phase and black rectangles represent dark phase of the light-dark cycle. In both experiments, animals were distributed in 4 groups: control (CTL) receiving vehicle (VEH) or MET and paradoxical sleep deprivation (PSD) receiving VEH or MET. In the acute treatment, animals received 1 single injection after 96 hours of sleep deprivation and were sacrificed 90 minutes later or were submitted to contextual fear conditioning (CFC) training and test. The trained animals were sacrificed 15 minutes after test, 24 hours after the training. In the chronic experiment, animals received 2 injections per day (07:00 and 19:00) during 4 days of sleep deprivation (or at the equivalent time point for the CTL group). Animals were sacrificed either 90 minutes after the last injection (21:00); immediately after sleep deprivation (07:00); 15 minutes after training or 15 minutes after the test in CFC.