Figure 4.

Effects of 45 min versus 15 min fear extinction training on the percentage of time spent in transitional sleep. These effects were observed during the 6 h sleep—wake recording period that immediately followed fear extinction training. Note the significant increase in transitional sleep during the first hour of sleep—wake recording in rats that received 45 min of training (Ext, n = 8; Failed-ext, n = 6) and the significant decrease in transitional sleep during the first 3 h of sleep—wake recording in rats that received only 15 min of training (No-ext, n = 8). Also note the significant increase in transitional sleep during the first 3 h of sleep—wake recording in Ext rats compared with both No-ext and Failed-ext rats. Error bars represent SEM; *p < 0.05, **p < 0.01, ***p < 0.001.