Effects of all-night exposure to ambient odour on dreams and affective state upon waking

Nováková, Lenka; Miletínová, Eva; Kliková, Monika; Bušková, Jitka

doi:10.1016/j.physbeh.2020.113265

Cited by 7 publications

(10 citation statements)

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“…Affirmative response to the item prompts a question about the sensory content (olfactory, gustatory, visual, auditory, somatosensory, kinaesthetic, and nociceptive; select all that apply). The instrument included several other items not used in the present study (see Martinec Nováková, et al [ 58 ] for details).…”

Section: Methodsmentioning

confidence: 99%

Olfaction-Related Factors Affecting Chemosensory Dream Content in a Sleep Laboratory

et al. 2021

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Mental activity in sleep often involves visual and auditory content. Chemosensory (olfactory and gustatory) experiences are less common and underexplored. The aim of the study was to identify olfaction-related factors that may affect the occurrence of chemosensory dream content. Specifically, we investigated the effects of all-night exposure to an ambient odour, participants’ appraisal of their current olfactory environment, their general propensity to notice odours and act on them (i.e., odour awareness), and their olfactory acuity. Sixty pre-screened healthy young adults underwent olfactory assessment, completed a measure of odour awareness, and spent three nights in weekly intervals in a sleep laboratory. The purpose of the first visit was to adapt to the experimental setting. On the second visit, half of them were exposed to the smell of vanillin or thioglycolic acid and the other half to an odourless control condition. On the third visit, they received control or stimulation in a balanced order. On each visit, data were collected twice: once from the first rapid eye movement (REM) stage that occurred after 3 a.m., and then shortly before getting up, usually from a non-REM stage. Participants were asked to report the presence of sensory dream content and to assess their current olfactory environment. Neither exposure, nor participants’ assessments of the ambient odour, or olfactory acuity affected reports of chemosensory dream content but they were more frequent in individuals with greater odour awareness. This finding may have implications for treatment when such experiences become unwanted or bothersome.

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Section: Methodsmentioning

confidence: 99%

Olfaction-Related Factors Affecting Chemosensory Dream Content in a Sleep Laboratory

et al. 2021

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“…Related to this, while we had carried out an a priori sample size computation (as detailed in the Participants section), we unfortunately found ourselves unable to meet the target N. This was because, firstly, we had obtained a lower dream recall rate of 75% compared to our previous study 90 , which had a rate of 83%. Secondly, we encountered technical issues during the v-PSG recordings, rendering fewer reports available for analysis.…”

Section: Discussionmentioning

confidence: 96%

“…The sample size was calculated a priori based on our previous study with similar design, in which a generally liked and disliked odor was used 90 . The mean difference between the control and exposure condition in dream pleasantness and emotional charge, averaged positive and negative emotions, and core affect ratings was about 1, with an SD of about 1.5.…”

Section: Methodsmentioning

confidence: 99%

Nocturnal exposure to a preferred ambient scent does not affect dream emotionality or post-sleep core affect valence in young adults

Martinec Nováková,

Miletínová,

Kliková

et al. 2024

Sci Rep

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Emotions experienced within sleep mentation (dreaming) affect mental functioning in waking life. There have been attempts at enhancing dream emotions using olfactory stimulation. Odors readily acquire affective value, but to profoundly influence emotional processing, they should bear personal significance for the perceiver rather than be generally pleasant. The main objective of the present sleep laboratory study was to examine whether prolonged nocturnal exposure to self-selected, preferred ambient room odor while asleep influences emotional aspects of sleep mentation and valence of post-sleep core affect. We asked twenty healthy participants (12 males, mean age 25 ± 4 years) to pick a commercially available scented room diffuser cartridge that most readily evoked positively valenced mental associations. In weekly intervals, the participants attended three sessions. After the adaptation visit, they were administered the odor exposure and odorless control condition in a balanced order. Participants were awakened five minutes into the first rapid eye movement (REM) stage that took place after 2:30 a.m. and, if they had been dreaming, they were asked to rate their mental sleep experience for pleasantness, emotional charge, and magnitude of positive and negative emotions and also to evaluate their post-sleep core affect valence. With rs < 0.20, no practically or statistically significant differences existed between exposure and control in any outcome measures. We conclude that in young, healthy participants, the practical value of olfactory stimulation with self-selected preferred scents for enhancement of dream emotions and post-sleep core affect valence is very limited.

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“…It has been shown that emotions or familiar senses linked to stimuli elicit much stronger responses ( Gao et al, 2019 ; Jain and Ramakrishnan, 2020 ). Emotional olfactory stimuli may be more effective in awake DoC patients ( Martinec Nováková et al, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Olfactory response is a potential sign of consciousness: electroencephalogram findings

Liang

et al. 2023

Front. Neurosci.

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ObjectiveThis study aimed to explore whether olfactory response can be a sign of consciousness and represent higher cognitive processing in patients with disorders of consciousness (DoC) using clinical and electroencephalogram data.MethodsTwenty-eight patients with DoC [13 vegetative states (VS)/unresponsive wakefulness syndrome (UWS) and 15 minimally conscious states (MCS)] were divided into two groups: the presence of olfactory response (ORES) group and the absence of olfactory response (N-ORES) group according to behavioral signs from different odors, i.e., vanillin, decanoic acid, and blank stimuli. We recorded an olfactory task-related electroencephalogram (EEG) and analyzed the relative power and functional connectivity at the whole-brain level in patients with DoC and healthy controls (HCs). After three months, the outcomes of DoC patients were followed up using the coma recovery scale-revised (CRS-R).ResultsA significant relationship was found between olfactory responses and the level of consciousness (χ2(1) = 6.892, p = 0.020). For olfactory EEG, N-ORES patients showed higher theta functional connectivity than ORES patients after stimulation with vanillin (p = 0.029; p = 0.027). Patients with N-ORES showed lower alpha and beta relative powers than HCs at the group level (p = 0.019; p = 0.033). After three months, 62.5% (10/16) of the ORES patients recovered consciousness compared to 16.7% (2/12) in the N-ORES group. The presence of olfactory response was significantly associated with an improvement in consciousness (χ2(1) = 5.882, p = 0.023).ConclusionOlfactory responses should be considered signs of consciousness. The differences in olfactory processing between DoC patients with and without olfactory responses may be a way to explore the neural correlates of olfactory consciousness in these patients. The olfactory response may help in the assessment of consciousness and may contribute to therapeutic orientation.

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Effects of all-night exposure to ambient odour on dreams and affective state upon waking

Cited by 7 publications

References 107 publications

Olfaction-Related Factors Affecting Chemosensory Dream Content in a Sleep Laboratory

Olfaction-Related Factors Affecting Chemosensory Dream Content in a Sleep Laboratory

Nocturnal exposure to a preferred ambient scent does not affect dream emotionality or post-sleep core affect valence in young adults

Olfactory response is a potential sign of consciousness: electroencephalogram findings

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