A pilot study on essential oil aroma stimulation for enhancing slow-wave EEG in sleeping brain - PubMed (original) (raw)

Randomized Controlled Trial

A pilot study on essential oil aroma stimulation for enhancing slow-wave EEG in sleeping brain

Li-Wei Ko et al. Sci Rep. 2021.

Abstract

Sleep quality is important to health and life quality. Lack of sleep can lead to a variety of health issues and reduce in daytime function. Recent study by Fultz et al. also indicated that sleep is crucial to brain metabolism. Delta power in sleep EEG often indicates good sleep quality while alpha power usually indicates sleep interruptions and poor sleep quality. Essential oil has been speculated to improve sleep quality. Previous studies also suggest essential oil aroma may affect human brain activity when applied awake. However, those studies were often not blinded, which makes the effectiveness and mechanism of aroma a heavily debated topic. In this study, we aim to explore the effect of essential oil aroma on human sleep quality and sleep EEG in a single-blinded setup. The aroma was released when the participants are asleep, which kept the influence of psychological expectation to the minimum. We recruited nine young, healthy participants with regular lifestyle and no sleep problem. All participants reported better sleep quality and more daytime vigorous after exposing to lavender aroma in sleep. We also observed that upon lavender aroma releases, alpha wave in wake stage was reduced while delta wave in slow-wave sleep (SWS) was increased. Lastly, we found that lavender oil promote occurrence of SWS. Overall, our study results show that essential oil aroma can be used to promote both subjective and objective sleep quality in healthy human subjects. This makes aroma intervention a potential solution for poor sleep quality and insomnia.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Figure 1

Experimental flowchart.

Figure 2

Figure 2

EEG power spectrum density analysis flowchart.

Figure 3

Figure 3

Lavender aroma stimuli improved subjective sleep quality. (A) Sleep indexes from questionnaire B. Sleep Disturbance was decreased while sleep wellness was increased in stimuli night. (B) Daytime SSS questionnaire ratings. SSS rating after stimuli night was higher than that of control night from 10:00 AM to 4:00 PM.

Figure 4

Figure 4

EEG spectrum during the release of lavender oil. (A) Cz channel, (B) Fz channel, (C) Oz channel, (D) T3 channel, (E) T4 channel.

Figure 4

Figure 4

EEG spectrum during the release of lavender oil. (A) Cz channel, (B) Fz channel, (C) Oz channel, (D) T3 channel, (E) T4 channel.

Figure 5

Figure 5

Lavender aroma promotes deeper sleep stages. (A) Sleep stages percentage in TIB. Percentage of N3 stage was increased in stimuli night. (B) Sleep stages percentage in TST. Percentage of N3 stage was increased while that of N2 was decreased in stimuli night.

Figure 6

Figure 6

Hypnogram of one of the participants (S1) drawn by sleep technician. N3 showed the same pattern in stimuli night and control night before stimuli onset (green arrow). Upon stimuli onset, N3 became longer and more frequent (orange arrow).

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