Abstract
Recent studies have found that sleep is necessary for some types of learning. Sleep dependent perceptual learning has been found on a texture discrimination task (TDT). Perceptual learning was defined as a decrease in duration of the stimulus-to-mask onset asynchrony (SOA) to discriminate a target. Stickgold et al (2000) found that improvement in perceptual learning was dependent on early, slow wave sleep (SWS) and late, rapid eye movement (REM) sleep. Gais et al (2000) similarly reported that learning on the TDT was dependent on early SWS rich sleep, and that the addition of late, REM rich sleep enhanced over all learning. Studies of the effect of strategic naps on the psychomotor performance of night workers found improvement in performance and alertness. No studies have examined the effect of day-time naps on perceptual learning. We tested the effect of day-time naps on perceptual learning in the TDT. Subjects were tested on the TDT four times in one day (9am, 12pm, 4pm and 7pm). The performance of control subjects run to date worsened by 27 ms across the four tests (2-tailed t-test, df = 15 t = 4.5, p<0.001), with the SOA increase not correlated with any increase in subjective sleepiness. Experimental subjects took naps (1 hour or 1 half hour naps) between the 2nd and 3rd test sessions. For each nap, EEG, EOG & EMG was recorded. In our preliminary findings, experimental subjects show a reversal in performance compared with the control group. Whereas the performance in the control group worsened throughout the four test sessions, performance in the experimental group improved after the nap and was significantly better than that of the controls (df = 17, t = 2.5, p = 0.02). Nap length and quality is also presented. We have shown that day-time sleep can reverse cognitive decline seen on a perceptual learning task.