Abstract
We examined the effect of napping behavior on the enhancement of perceptual learning (PL) during sleep. In a mini-longitudinal study, habitual and non-habitual nappers were randomly assigned to five weeks of nap practice (at least 3 naps per week) or nap restriction (no naps). PL was tested pre- and post-intervention using a texture discrimination task in a nap paradigm (with texture targets tested in different spatial locations at each time point). For each visit, we calculated a within-day difference score between morning and evening test sessions to measure performance change following an EEG-recorded nap. At time point 1, habitual nappers showed PL following a nap, whereas non-habitual nappers did not show improvement. At the end of the intervention, at time point 2, both habitual nappers restricted from napping and non-nappers practicing napping showed lower magnitude of PL than the habitual nappers allowed to nap and non-nappers restricted from napping. That is, when napping behavior was congruent with nap habits, typical sleep-dependent PL occurred. When napping behavior and habits were incongruent, PL was not found. We found no differences in the amount of each sleep stage between habitual and non-habitual nappers. However, during non-rapid-eye-movement sleep, habitual nappers produced greater sleep spindle densities over parietal and occipital sites, as well as greater slow wave activity power density over central and parietal sites. In conclusion, although sleep, including naps, has been repeatedly demonstrated to play an important role in the consolidation of PL, the results from our experimental intervention indicate that napping may only benefit PL in people who habitually nap. These differences may be related to the magnitude of specific sleep features. Furthermore, altering a person's normal sleep/wake rhythm by adding or removing naps may not be beneficial for cognitive performance.
Meeting abstract presented at VSS 2014