OBJECTIVE Odor presentation is a crucial tool in the experimental investigation of dreaming since odors rarely cause arousal, and are processed in the brain during sleep. Our previous study demonstrated that the presentation of a preferred odor during rapid eye movement (REM) sleep-induced negative dream emotions. However, preference and familiarity of an odor are known to be strongly related to each other in olfactory perception. Consequently, the above result might have been due to the confounding effects of familiarity. Therefore, the present study was designed to clarify the effects of an individual's degree of familiarity with an odor on negative emotions experienced when dreaming. METHODS The airflow with phenylethyl alcohol (PEA: rose-like smell) was presented as a stimulus of experimental condition, and odorless airflow was presented as the control. Participants who were familiar (n = 7) and unfamiliar (n = 7) with the odor of PEA experienced both conditions during REM sleep in the second and later sleep cycle. Then, they were awakened, and they rated the characteristics of their dream using a questionnaire. RESULTS AND CONCLUSIONS Participants who were familiar with the odor of PEA rated their dreams more negatively in the experimental condition relative to the control condition. It is concluded based on these results that a familiar odor may induce negative emotion in dreams, possibly because familiar odors tend to be perceived more strongly, and the olfactory pathway has direct connections to the amygdala, which is primarily involved in processing negative emotions.

中文翻译：

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在健康的青少年中，出现熟悉的气味会在快速眼动（REM）睡眠期间诱发负面的梦境情感。

目的气味表现是做梦实验研究中的重要工具，因为气味很少引起唤醒，并且在睡眠时会在大脑中产生。我们之前的研究表明，在快速眼动（REM）睡眠引起的负性梦想情感期间会呈现出一种偏好的气味。然而，已知气味的喜好和熟悉在嗅觉感知中彼此密切相关。因此，以上结果可能是由于熟悉的混杂影响所致。因此，本研究旨在阐明个人对气味的熟悉程度对梦中经历的负面情绪的影响。方法用苯乙醇（PEA：玫瑰味）气流刺激实验条件，并以无味的气流作为对照。熟悉（n = 7）和不熟悉（n = 7）的PEA气味的参与者在第二个及以后的睡眠周期的REM睡眠中都经历了这两种情况。然后，他们被唤醒，并使用问卷对自己梦dream以求的特征进行评分。结果与结论熟悉PEA气味的参与者在实验条件下相对于对照条件对梦想的评价更为负面。根据这些结果得出结论，熟悉的气味可能会在梦中诱发负面情绪，这可能是因为熟悉的气味往往会被强烈感知，并且嗅觉途径与杏仁核直接相关，杏仁核主要参与处理负面情绪。熟悉（n = 7）和不熟悉（n = 7）的PEA气味的参与者在第二个及以后的睡眠周期的REM睡眠中都经历了这两种情况。然后，他们被唤醒，并使用问卷对自己梦dream以求的特征进行评分。结果与结论熟悉PEA气味的参与者在实验条件下相对于对照条件对自己的梦想的评价更为负面。根据这些结果得出结论，熟悉的气味可能会在梦中诱发负面情绪，这可能是因为熟悉的气味往往会被强烈感知，并且嗅觉途径与杏仁核直接相关，杏仁核主要参与处理负面情绪。熟悉（n = 7）和不熟悉（n = 7）的PEA气味的参与者在第二个及以后的睡眠周期的REM睡眠中都经历了这两种情况。然后，他们被唤醒，并使用问卷对自己梦dream以求的特征进行评分。结果与结论熟悉PEA气味的参与者在实验条件下相对于对照条件对自己的梦想的评价更为负面。根据这些结果得出结论，熟悉的气味可能会在梦中诱发负面情绪，这可能是因为熟悉的气味往往会被强烈感知，并且嗅觉途径与杏仁核直接相关，杏仁核主要参与处理负面情绪。他们被唤醒，并使用问卷调查了他们梦the以求的特征。结果与结论熟悉PEA气味的参与者在实验条件下相对于对照条件对自己的梦想的评价更为负面。根据这些结果得出结论，熟悉的气味可能会在梦中诱发负面情绪，这可能是因为熟悉的气味往往会被强烈感知，并且嗅觉途径与杏仁核直接相关，杏仁核主要参与处理负面情绪。他们被唤醒，并使用问卷调查了他们梦the以求的特征。结果与结论熟悉PEA气味的参与者在实验条件下相对于对照条件对梦想的评价更为负面。根据这些结果得出结论，熟悉的气味可能会在梦中诱发负面情绪，这可能是因为熟悉的气味往往会被强烈感知，并且嗅觉途径与杏仁核直接相关，杏仁核主要参与处理负面情绪。