Memory encoding
napping
Most nap studies investigating effects on memory encoding have used longer naps of 90 min or more to make provision for greater amounts of NREM sleep [In addition, significant effects of nap length on encoding performance remained after statistically controlling for sleep inertia, suggesting that sleep inertia did not explain the relatively better encoding performance in the 30 min nap. Moreover, within 30 min of waking, DSST reaction times returned to baseline levels for both the 30 min and 60 min naps, suggesting that sleep inertia had dissipated prior to encoding, which commenced 90 min after waking.A boost in vigilance may have facilitated superior memory encoding as the 30 min nap was associated with vigilance improvement up to 240 min after waking. However, we did not observe vigilance improvement to be significantly correlated with encoding performance [The length of nocturnal sleep in the night(s) prior to napping could also influence nap effects on memory encoding. Our previous work in adolescents using the same picture encoding task found that a longer 90 min nap following a night of sleep restriction significantly facilitated memory encoding [Differences may also arise depending on whether testing occurred on the same day or after intervening sleep. In our prior studies with adolescents, participants retrieved the pictures 2 days after recovery from sleep restriction. As such, the subsequent sleep opportunity may have conferred additional benefits to the encoded material [