The Effects of Self-Guided Meditation and Napping on Memory Consolidation in Humans

Abstract

Numerous studies have reported that, compared to an equivalent period of wakefulness, post-training sleep (overnight or daytime naps) benefits memory consolidation (Diekelmann & Born, 2010; Mednick, Nakayama, & Stickgold, 2003; Plihal & Born, 1999; Walker et al., 2003). However, most investigations have employed various forms of “active wakefulness” (e.g., sensorimotor and cognitive tasks) as a comparison condition for sleep, while few studies have examined the role of “quiet wakefulness” in memory consolidation, even though some of the EEG oscillations during quiet waking resemble those present in sleep (e.g., increased activity in the theta-alpha range) (Brokaw et al., 2016). This study aimed to examine the consolidation of declarative (word-pair associates) and non-declarative (marble maze visuo-motor task) learning over a 60-minutes time interval (with continuous EEG monitoring) filled with either (A) napping; (B) active-waking (watching a video); or (C) quiet-waking (self-guided meditation). The results of the current study suggested that memory consolidation may not be a sleep-specific- phenomenon. In fact, quiet wakefulness appeared to be more advantageous than a short nap for the consolidation of declarative memories. This study also found that SWS exerts significant effects on the retention of non-declarative memory. For nappers, the absence of SWS resulted in noticeable performance enhancements compared to participants who entered SWS. Thus, it is possible that SWS plays a disadvantageous role in the consolidation of procedural memory. It is thought that sleep inertia caused by SWS is partly responsible for the impairments in tasks procedural memory. The findings of current study contribute to the understanding of memory consolidation and provide insights about the role of waking states for future studies.