Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 10 (1), 1227

How Odor Cues Help to Optimize Learning During Sleep in a Real Life-Setting


How Odor Cues Help to Optimize Learning During Sleep in a Real Life-Setting

Franziska Neumann et al. Sci Rep.


Effortless learning during sleep is everybody's dream. Several studies found that presenting odor cues during learning and selectively during slow wave sleep increases learning success. The current study extends previous research in three aspects to test for optimization and practical applicability of this cueing effect: We (1) performed a field study of vocabulary-learning in a regular school setting, (2) stimulated with odor cues during the whole night without sleep monitoring, and (3) applied the odor additionally as retrieval cue in a subsequent test. We found an odor cueing effect with comparable effect sizes (d between 0.6 and 1.2) as studies with sleep monitoring and selective cueing. Further, we observed some (non-significant) indication for a further performance benefit with additional cueing during the recall test. Our results replicate previous findings and provide important extensions: First, the odor effect also works outside the lab. Second, continuous cueing at night produces similar effect sizes as a study with selective cueing in specific sleep stages. Whether odor cueing during memory recall further increases memory performance hast to be shown in future studies. Overall, our results extend the knowledge on odor cueing effects and provide a realistic practical perspective on it.

Conflict of interest statement

The authors declare no competing interests.


Figure 1
Figure 1
Paradigm: The study consisted of four steps: (I) Initial presentation of the material at school (II) Learning at home, (III) Sleep at home (7 nights) and (IV) a vocabulary test at school 7 days after the learning unit. No odor cue was applied in Condition N. In the LT condition, students from the test group received odor cues during learning at home (L) and during the vocabulary test (T) seven days after the learning unit at school. In condition LS, they received odor cues during learning and during sleep in seven successive nights at home. Finally, in the condition LST, they received odor cues during learning at home, during sleep at home and during the final vocabulary test at school. Students from the control group learned the identical vocabulary material as the test group, but received no odor cues neither during learning nor during sleep and during the tests.
Figure 2
Figure 2
Results: Small icons (stars and circles) represent data from individual participants. The data of the test group is in red, of the control group is blue. Larger open circles represent averages across classes ± SEM. Filled circles represent data from Class 1, stars represent data from Class 2. The different columns, separated by vertical dashed black lines, represent the different experimental conditions (N: no odor cue; LT: odor cue during learning and test; LS: odor cue during learning and during sleep; LST: odor cue during learning, sleep and test). Horizontal jitter across icons within monochrome sub-columns is due to presentation purposes. We found smaller numbers of errors LS and LST compared to conditions N and LT, and a tendency for smaller errors in LST compared to LS. Class 2 provided no data for condition LST. Data are normalized with respect to the number of vocabulary words tested in the respective vocabulary tests.

Similar articles

See all similar articles


    1. Gregory, R. Seeing through illusions. (Oxford University Press, 2009).
    1. Kornmeier J, Mayer G. The alien in the forest OR when temporal context dominates perception. Perception. 2014;43:1270–1274. doi: 10.1068/p7844. - DOI - PubMed
    1. van Rooij, M., Atmanspacher, H. & Kornmeier, J. Hysteresis in Processing of Perceptual Ambiguity on Three Different Time Scales. in Proceedings of the 38th Annual Conference of the Cognitive Science Society (eds. Papafragou, A., Grodner, D., Mirman, D. & Trueswell, J.) 568–573 (2016).
    1. Liaci Emanuela, Fischer Andreas, Atmanspacher Harald, Heinrichs Markus, Tebartz van Elst Ludger, Kornmeier Jürgen. Positive and negative hysteresis effects for the perception of geometric and emotional ambiguities. PLOS ONE. 2018;13(9):e0202398. doi: 10.1371/journal.pone.0202398. - DOI - PMC - PubMed
    1. Chatterjee A, Strauss ME, Smyth KA, Whitehouse PJ. Personality Changes in Alzheimer’s Disease. Arch. Neurol. 1992;49:486–491. doi: 10.1001/archneur.1992.00530290070014. - DOI - PubMed