The Effect Of Sleep On Memory

Sleep has a very important physiological significance for individuals,and involves in the process of memory and a variety of cognitive processes.Studies have shown that post-learning sleep helps to keep and improve memory compared with wake interval.Sleep is the best time for memory consolidation,and newly acquired short-term memory can be transformed into more stable and long-lasting memory without active effort during the off-line period.In addition,researches have showed that the brain would unconsciously "review" the memory during sleep,promoting the consolidation of memory.And we could enhance the consolidation of memory,especially the declarative memory,by cuing memory during sleep.In addition,according to a large number of distributed practice studies of semantic memory,active repeated practice can also promote the long-term retention of declarative memory.Sleep plays an important role in the consolidation of memory,and it is very important to improve the efficiency of relearning on declarative memory for better promotions of work efficiency,therefore it is of great importance to study whether sleep can promote the efficiency of relearning on declarative memory.However,there are few studies about the relationship between sleep and relearning on declarative memory,and the results are controversial.In view of this,we conducted the following three studies:Study I applied a meta-analysis to explore the effect of sleep target memory reactivation on memory.After selection,1562 were found,and finally 29 articles containing 48 independent studies were included in the present meta-analysis.The results showed that 1)Application of target memory reactivation could significantly improve the memory consolidation,but the effects was affected by many factors;2)The effects of the target memory reactivation in the sleep period was better than that of the wake period,and the result was significant.3)Auditory and olfactory stimuli as cues of target memory reactivation could effectively promote memory consolidation,but the application of auditory stimuli was more popular,and the promotion of memory was better by using auditory stimuli.4)In slow wave sleep stage,the effect of target memory reactivation was best to promote memory consolidation,especially in the case of declarative memory;Study II investigated the effects of sleep on the relearning efficiency of semantic memory(a kind of declarative memory)and the retention of long-term memory after relearning.The results showed that the semantic memory was not different between the post-learning sleep and the post-learning wake,and the effect of post-learning sleep on semantic memory relearning was not observed,but relearning could obviously improve the performance of semantic memory.Study III aimed to further explore the effects of sleep on episodic memory learning(another kind of declarative memory)comparing with study II.The results showed that the post-learning sleep,compared with the post-learning wake,increased the consolidation of episodic declarative memory after 12 hours.However,there was no significant difference in trials and the retention of memory between the post-learning sleep and the post-learning wake.In addition,there was also no significant difference between the wake group and the sleep group in the retention of long-term memory.These results suggested that sleep could indeed promote declarative memory consolidation,but the effects of sleep on the relearning efficiency of episodic memory and the retention of long-time memory was not sure.Combined,the target memory reactivation during sleep could effectively promote the consolidation of memory,especially the consolidation of declarative memory,and post-learning sleep could also promote the consolidation of declarative memory.There were no significant promotions of the relearning efficiency of declarative memory and the retention of long-term memory through post-learning sleep.This study first quantified the effects of sleep target memory reactivation on memory consolidation,and further examined the effects of postlearning sleep on declarative memory consolidation,the relationship between postlearning sleep and declarative memory relearning efficiency.It provides a theoretical basis for the investigation of the relationship between sleep and memory consolidation,as well as enriched theories of the relationship of post-learning sleep and relearning.