# Study: Naps Preserve Associative but not Item Memory Performance **URL:** \ **Category:** Neuroscience, Psychology, and Health\ **Tags:** sleep\ **Created:** [March 24, 2015, 7:16am UTC](https://forum.artofmemory.com/t/study-naps-preserve-associative-but-not-item-memory-performance/30476 "2015-03-24T07:16:22Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Josh](https://forum.artofmemory.com/user_avatar/forum.artofmemory.com/josh/32/21_2.png) [@Josh](https://forum.artofmemory.com/u/Josh)\ **Post date:** [March 24, 2015, 7:16am UTC](https://forum.artofmemory.com/t/study-naps-preserve-associative-but-not-item-memory-performance/30476/1 "2015-03-24T07:16:22Z")
I don’t have access to the full text, but there is an article about it here: “[A short nap may make memory five times better](http://www.upi.com/Science_News/2015/03/23/A-short-nap-may-make-memory-five-times-better/9181427162911/)” > The team looked at 41 participants, and they had them look at and try to remember 90 words and 120 word pairs. They made sure the word pairs were not similar, like using the words "milk" and "taxi" as a pair so the words were not easy to remember together. Half the participants took a nap no longer than 90 minutes and half watched a DVD after looking at the words. The people who took a nap remembered the words far better. [Nap sleep preserves associative but not item memory performance](http://www.sciencedirect.com/science/article/pii/S1074742715000362) > Many studies have shown that sleep improves memory performance, and that even short naps during the day are beneficial. Certain physiological components of sleep such as spindles and slow-wave-sleep are thought to be particularly important for memory consolidation. The aim of this experiment was to reveal the role of naps for hippocampus-dependent associative memory (AM) and hippocampus-independent item memory (IM) alongside their corresponding ERP old/new effects. Participants learnt single words and word-pairs before performing an IM- and an AM-test (baseline). One group was subsequently allowed to nap (∼90 min) while the other watched DVDs (control group). Afterwards, both groups performed a final IM- and AM-test for the learned stimuli (posttest). IM performance decreased for both groups, while AM performance decreased for the control group but remained constant for the nap group, consistent with predictions concerning the selective impact of napping on hippocampus-dependent recognition. Putative ERP correlates of familiarity and recollection were observed in the IM posttest, whereas only the later recollection-related effect was present in the AM test. Notably, none of these effects varied with group. Positive correlations were observed between spindle density during slow-wave-sleep and AM posttest performance as well as between spindle density during non-REM sleep and AM baseline performance, showing that successful learning and retrieval both before and after sleep relates to spindle density during nap sleep. Together, these results speak for a selective beneficial impact of naps on hippocampus-dependent memories. ---
**Author:** ![taijutsu.memory](https://forum.artofmemory.com/user_avatar/forum.artofmemory.com/taijutsu.memory/32/3688_2.png) [@taijutsu.memory](https://forum.artofmemory.com/u/taijutsu.memory)\ **Post date:** [March 24, 2015, 1:08pm UTC](https://forum.artofmemory.com/t/study-naps-preserve-associative-but-not-item-memory-performance/30476/2 "2015-03-24T13:08:56Z")
41 participants, It is a very small number, and there has been no study of cluster analysis, or Wavelets or other statistical tools that allow isolate the variables that are used to study what may have caused noise. Despite all these caveats, intuitively seems very coherent to suppose that nap has a very important role in the intellectual development, by improving many different skills and, as discussed above, for making more organized thinking, and this can be applied in virtually all areas of knowledge. ---
**Author:** ![bruno](https://forum.artofmemory.com/user_avatar/forum.artofmemory.com/bruno/32/2822_2.png) [@bruno](https://forum.artofmemory.com/u/bruno)\ **Post date:** [March 24, 2015, 2:33pm UTC](https://forum.artofmemory.com/t/study-naps-preserve-associative-but-not-item-memory-performance/30476/3 "2015-03-24T14:33:35Z")
Thanks Josh, it’s interesting. Here is the full text, enclosed in my post. _“Just a brief sleep from 45 to 60 minutes improves memory by a factor of five”_. I just had a quick look on the paper then I might be wrong, but this sounds to be a usual overclaim from the journalist. Concerning associative memory, Mean Pr-scores (hits minus false alarms) goes from around 0.41 for sleep condition to 0.3 for DvD condition. This is not a huge effect size. As taijutsu.memory pointed out, 41 subjects is not big. But it’s just enough to reach significant results there. Edit : Maybe some people don’t know what is statistical significance is. It should help people wants to read scientific article from times to times. Sorry for people who do know what it is. In short, you assume a null hypothesis (generally the opposite of you want to prove) in this case it would be “there is no difference between the DvD condition and the sleep condition” and a statistic, in this case it would be the mean difference in Pr Scores, and you check how far goes this statistics under your null hypothesis assumption. If it reachs a pre-determined threshold (generally in the 5% most extreme area), this is statically significant, and you can publish your results. In a nutshell the global idea is “if there was no effect, such an extreme statistics would occur with less than 5% of chance: then there is an effect”. ---
**Author:** ![Josh](https://forum.artofmemory.com/user_avatar/forum.artofmemory.com/josh/32/21_2.png) [@Josh](https://forum.artofmemory.com/u/Josh)\ **Post date:** [March 26, 2015, 5:05am UTC](https://forum.artofmemory.com/t/study-naps-preserve-associative-but-not-item-memory-performance/30476/4 "2015-03-26T05:05:01Z")
> [@bruno](#): > > …this sounds to be a usual overclaim from the journalist. That wouldn’t be surprising at all. 🙂