The purpose of this study was to reveal the effect of aroma on a psychological and physiological response and mental work performance after a short nap. Nine participants took a nap in a darkroom while taking their brain waves. Before and after the nap, they evaluated for ease of sleeping and waking, and worked the d2 test and the word creation test. There were three aroma conditions: orange-bitter oil with high preference and clove bud oil with low preference, and no essential oil. There was no difference in the frequency content of the EEG among three aroma conditions. There were also no significant differences in the evaluation of ease of sleeping and waking. However, it was slightly harder to sleep and easier to wake up in the clove bud condition. And it was slightly harder to wake up in the orange-bitter condition. To compare the mental work performance, three indices were set: d2 achievement rate “Pa”, d2 error rate “Pm”, and number of word responses “N”. In all three aroma conditions, all three indices did not increase significantly after the nap. In the differences of indices between after and before the nap, there were no significant differences among the aroma conditions. However, in the orange-bitter condition, “Pa” tended to be slightly higher than other conditions, and “Pm” slightly lower than the others. “N” was difficult to compare because of the wide variation.

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