Essential oils (EOs) are widely used for various purposes, however, their claimed effects are often not supported by empirical data. Previous findings have highlighted the importance of psychological factors (e.g. expectations) in their mechanism of action. The present study investigated the effects of an ingested placebo pill and inhaled rosemary and lavender oils on alertness and heart rate, as well as actual and perceived performance in a sustained attention task. 128 young adults, randomly allocated to four groups (rosemary, lavender, placebo pill with stimulant suggestion, and control), completed a vigilance task before and after the respective intervention. Compared to the control condition, no effects of the three interventions were found on actual changes in sustained attention, alertness, or heart rate. Both EOs and the placebo pill evoked positive expectations regarding cognitive performance and alertness. Expectations predicted perceived changes in alertness and heart rate, but not in cognitive performance. No differences between the two EOs and the placebo intervention were found in any respect. Psychological mechanisms behind the effects of inhaled EOs and placebos might be overlapping.
Effects of inhaled essential oils (EOs) cannot be explained by pharmacological mechanisms alone. The study aimed to investigate the effects of pleasantness of and expectancies evoked by EOs. A double-blind experiment with a within-subject design was carried out with the participation of 33 volunteering adults (15.2% male; mean age 37.7 ± 10.90 years). Participants were exposed to three EOs (rosemary, lavender, and eucalyptus) for three minutes in a quasi-random order, expectations were simply assessed prior to exposure. Subjective (perceived) changes in alertness, heart rate (HR), and blood pressure (BP), and objective changes in HR, BP, and indices of heart rate variability were recorded. Significant group-level differences in changes in alertness and no differences for the cardiovascular variables were found. Participants' expectations predicted changes in alertness in the case of rosemary and lavender oils but had no impact on cardiovascular variables. EOs' pleasantness had no effect on any assessed variable. Perceived changes in BP and HR were not related to the respective objective changes but were connected to perceived changes in alertness. Expectancies play an important role in the subjective effects of inhaled EOs. Perceived subjective changes are used to estimate changes in non-conscious (e.g., visceral) states.
BotaniqueLa famille des Primulac6es contient plus de 4oo esp6ces qui, pour la plupart, se trouvent dans l'h6misph~re Nord du globe. Du point de vue de la th6rapie, on fait appel surtout fi la primev6re des pr6s (Primula officinalis [L.] Hill.) et ~ la primev6re sylvestre (Primula elatior [L.] Hill.). Primula officinalis se trouve sur des terrains secs ~ bouleaux, des bois clairsem6s de p~turages de montagne, des gazons situ6s sur terrain rocheux. Cette plante fleurit en avril-mai, pousse fi une hauteur de lo fi 2o cm avec des racines de 1 fi 5 cm de long et 0,5 cm d'@aisseur. Sa fleur est typique : son calice est permanent et la corolle en tube jaune pale se termine en 5 lobes 6tal6s et concaves. P. eIatior pousse dans les parties montagneuses. Ses fleurs (1 ou 2) sont d'un jaune soufre et ses feuilles ne sont pas velues. On en utilise soit la fleur (Primulaeflos), soit les racines et rhizomes (Primulae radix) [2, 7, 15]. Constituants principauxLes principes actifs principattx sont des saponines triterp6ni-ques qui se trouvent dans toutes les parties de la primev~re. On les trouve/: raison de 4 a lO % dans la racine, mais on n'en trouve qu'un cinqui~me de cette quantit6 dans les parties sup6rieures. Dans les fleurs se trouvent aussi des flavono'/des et des carot6noi'des ~ cgt6 des saponines [4, 5, 12, 17, 18, 2o, 26].Les saponines de la fleur et de la racine de la primev~re en provoquant une irritation de la muqueuse gastrique entrainent une stimulation de la s6cr6tion des glandes salivaires et au-del/: de la muqueuse respiratoire. Elles stimulent le mouvement mucociliaire permettant l'excr6tion des glaires des voies respiratoires. En plus des effets mucofluidifiant, expectorant et tussipl6ge, la primev~re a aussi un effet antiinflammatoire, 16g~rement diur6tique et, selon certaines sources, 16g~rement s6datif. L'indication de la primev~re est donc la toux improductive, le catarrhe des voies respiratoires, la bronchite chronique, en monoth6rapie ou en association avec d'autres drogues [1,[3][4][5]8,12,26].
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