Abstract
Learning on a variety of perceptual and motor tasks requires a night's sleep. In the present research we add a new dimension to our understanding of sleep-dependent learning by demonstrating a special role for daytime napping. We have previously shown that repeated, within-day testing on a texture discrimination task (TDT) (without sleep) produced retinotopically specific deterioration in performance; but an hour nap restored performance to baseline for two subsequent testing sessions. In the current study, we investigated two questions: 1) Whether deterioration accumulates over the inter-test interval or from stimulus exposure during testing, 2) Whether longer naps that include both slow wave sleep (SWS) and rapid eye movement (REM) sleep produce improvement beyond baseline performance. All subjects performed the TDT in the morning and evening of day one (tests 1 & 2), and once the following morning (test 3). Some subjects took a nap with EEG recording (60 – 100min) between tests 1 and 2. In the non-nappers, we found that performance deteriorated similarly when tests were separated by 8hrs as by 2hrs. Thus, stimulus exposure rather than inter-test interval produces TDT deterioration. In the nappers, we found significant TDT learning and the learning was significantly correlated with the product of SWS & REM durations in the nap. Our findings demonstrate that a daytime nap containing both SWS and REM is effective for task-specific learning, similar to findings for nocturnal sleep-dependent learning. Further, without a daytime nap, visual discrimination deteriorates with repeated exposure to a stimulus.