Effortless learning during sleep is the dream of many people.
The supportive effect of smells on learning success when presented both during learning and sleep was first proven in an extensive sleep laboratory study.
Researchers at the University of Freiburg – Medical Center, the Freiburg Institute for Frontier Areas of Psychology and Mental Health (IGPP) and the Faculty of Biology at the University of Freiburg have now shown that this effect can be also achieved very easily outside the lab.
For the study, pupils in two school classes learned English vocabulary – with and without scent sticks during the learning period and also at night. The students remembered the vocabulary much better with a scent. The study was published in the Nature Group’s Open Access journal Scientific Reports on 27 January 2020.
“We showed that the supportive effect of fragrances works very reliably in everyday life and can be used in a targeted way,” said study leader PD Dr. Jürgen Kornmeier, head of the Perception and Cognition Research Group at the Freiburg-based IGPP and scientist at the Department of Psychiatry and Psychotherapy at the University of Freiburg – Medical Center in Germany.
The smell of roses when learning and sleeping
For the study, first author and student teacher Franziska Neumann conducted several experiments with 54 students from two 6th grade classes of a school in southern Germany.
The young participants from the test group were asked to place rose-scented incense sticks on their desks at home while learning English vocabulary and on the bedside table next to the bed at night.
In another experiment, they also placed the incense sticks on the table next to them during a vocabulary test at school during an English test.
The results were compared with test results in which no incense sticks were used during one or more phases.
Neuroscience, neurobiology, brain research, open access, open science, learning, Memory, olfaction, sleep, neuroplasticity, University of Freiburg
“The students showed a significant increase in learning success by about 30 percent if the incense sticks were used during both the learning and sleeping phases,” says Neumann.
The results also suggest that the additional use of the incense sticks during the vocabulary test promotes memory.
Findings are suitable for everyday use
“One particular finding beyond the seminal initial study was, that the fragrance also works when it is present all night,” says Kornmeier.
“This makes the findings suitable for everyday use.” Previous studies had assumed that the fragrance needs to be only present during a particularly sensitive sleeping phase. However, since this sleep phase needs to be determined by an effortful measurement of brain activity by means of an electroencephalogram (EEG) in the sleep laboratory, this finding was not suitable for everyday use. “Our study shows that we can make learning during sleep easier.
And who would have thought that our nose could help considerably in this,” says Kornmeier.
Nowadays, alternative medicine is a novel strategy for improving health and quality of life.1 Aromatherapy is one of the integrative treatments that use essential oil to enhance mental, emotional, and physical well-being.2
Essential oil is commonly used for inhalation and typical applications, for example, bath and skin care products for relaxing the body and reducing symptoms of stress, depression, and anxiety.3
Aroma is a pleasant odor and is usually scented during drinking and eating.4 Inhaling of odorant molecules activates the olfactory system by sending the nerve impulse from olfactory receptors to olfactory bulbs via olfactory nerves (CN I).5
The nerve impulse passes through the brain regions of piriform cortex, orbitofrontal cortex, hypothalamus, and limbic system, especially amygdala and hippocampus. These regions of the brain regulate conscious discrimination, olfactory memory, and olfactory emotion.5
Recently, essential oil studies have focused on their effects for both animals and humans. Animal studies demonstrated that lavender and rose essential oils modulate neurotransmitter system which exert anxiolytic-like effect.6, 7
Clinical studies showed that inhalation of essential oils modulates mood, cognitive performance, brain wave, salivary cortisol level, heart rate, and blood pressure.8, 9, 10, 11 Hence essential oil inhalation could produce pharmacological, physiological, and psychological alteration in both animals and humans.
Coffee (Coffea Arabica L.), a plant in Rubiaceae family, has been used worldwide for beverage. Coffee is one of the most consumed beverages in the world.12
Coffee produces various aroma characteristics while drinking. Numerous studies showed the health benefits of drinking coffee: for example, reducing risk of cardiovascular disease, diabetes mellitus, and cancer.12, 13
Ullrich et al. reported that consumption of coffee improved mood, self-judgment, and cognitive performance.14 Recently, Seo et al. reported that aroma of roasted coffee bean could reduce emotional stress in rats of which the induced stress was by sleep deprivation.15
The roasted coffee bean aroma exerts relaxation in stressed rats by modulating mRNA and antioxidant protein expression levels of the rats’ brains.15
However, reports on the effects of inhaling of coffee fragrance on psychological, physiological, and psychomotor parameters in human are rare.
Therefore, this study was performed to investigate the effects of inhaling coffee fragrance, rather than aroma, on the alterations of working memory, mood, salivary cortisol level, blood pressure, and heart rate in adolescent population.
University of Freiburg