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The Connection Between Scent and the Brain

— The Mechanisms of Memory, Emotion, and Performance —

Published on December 28, 2024 · Updated on July 23, 2025

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Scent is more than something that simply feels pleasant. It can awaken memory, regulate emotion, and enhance concentration—
and contemporary neuroscience is steadily revealing how scent influences the brain.

Does Scent Influence the Brain?

The effects of scent on the brain have long been a subject of scientific research. Among the five senses, olfaction is unique in that it can act directly on the limbic system, the brain region closely involved in emotion and memory. For this reason, scent is considered to have a particularly strong influence on psychological state and cognitive function.

For example, the experience of “smelling a certain scent and suddenly remembering the past” reflects how closely olfaction is linked to memory. This occurs because olfactory information is transmitted directly to limbic structures, including the hippocampus, which plays a key role in memory. The relationship between scent and memory has also gained attention in recent neuroscience research, and applications are increasingly explored in medicine and psychotherapy.

Introduction: How Scent Communicates with the Brain

Many people intuitively sense that scent influences their mood, memories, and physical condition in everyday life. However, until relatively recently, the mechanisms behind these effects had not been fully understood. Advances in scientific research are now gradually clarifying how scent interacts with the brain.

Scent is detected by specialized sensory cells—olfactory receptors—located deep within the nasal cavity. When these receptors receive aromatic molecules, the information is transmitted to the olfactory bulb in the brain. From there, the signals are sent directly to the limbic system, which governs emotion and memory. This direct pathway explains why a specific scent can suddenly bring back vivid memories from the past.

Beyond emotion and memory, scent also influences a wide range of bodily functions, including the autonomic nervous system and hormone secretion. Scientific studies have shown, for example, that calming scents can stimulate the release of hormones that reduce stress in the brain, while stimulating scents can activate neural activity associated with heightened focus and alertness.

In this way, scent is not merely a tool for momentary mood change. It is increasingly recognized as a scientifically grounded means of supporting balance in both mind and body.

Neuroscience Perspectives on Scent: Connections with Brain Waves and Hormones

When we perceive a scent, complex processes are set in motion within the brain. Recent scientific research has revealed that scent can directly influence patterns of brain activity as well as the secretion of hormones.

The effects of scent on brain waves have drawn particular attention. For example, when we inhale a scent associated with relaxation, alpha waves in the brain tend to increase. An increase in alpha waves is linked to a calm, relaxed mental state. In contrast, scents that promote focus are associated with an increase in beta waves, reflecting heightened alertness and concentration.

Scent also plays a role in regulating the release of various hormones in the brain. Pleasant aromas have been shown to suppress the secretion of cortisol, a hormone that rises under stress. Conversely, scents associated with positive emotions can stimulate the release of neurotransmitters such as serotonin and dopamine, which contribute to feelings of wellbeing.

In addition, scent influences the autonomic nervous system. Aromas with relaxing properties activate the parasympathetic nervous system, shifting the body into a state of rest and recovery. On the other hand, invigorating scents stimulate the sympathetic nervous system, enhancing alertness, focus, and overall performance.

In this way, scent plays an essential role in regulating our emotional and physical states, acting through brain waves, hormonal balance, and the autonomic nervous system.

The Chemistry of Scent: How Components Work and Act on the Body

The effects of scent on the brain and body are largely due to specific chemical components contained within aromatic substances. Each aromatic compound interacts with the brain and nervous system in its own distinct way.

For example, citrus scents such as orange contain a compound called limonene, which is known to stabilize mood and enhance feelings of happiness. Limonene promotes the release of serotonin, a neurotransmitter in the brain, helping to reduce stress and create a sense of emotional calm.

Menthol, a key component found in peppermint, is widely recognized for its refreshing sensation. Menthol stimulates the brain, helping to increase alertness, clear mental fog, and counteract drowsiness. For this reason, it is often used in situations that require sustained concentration.

Ylang-ylang contains compounds such as germacrene and β-caryophyllene, which stimulate the parasympathetic nervous system and promote deep relaxation. These components are particularly effective in easing tension and anxiety, helping both the mind and body return to a calmer state.

Sandalwood contains α-santalol, a compound known for its calming effects on the brain. α-Santalol enhances neural inhibition, making it effective for stress reduction and for improving the quality of sleep.

By understanding the specific actions of these aromatic components, we can use scent more intentionally and effectively in everyday life, choosing aromas that support our mental clarity, emotional balance, and physical wellbeing.

Experimental Research and Practical Applications

The effects of scent have been supported by a growing body of scientific research. Findings from these studies have led to real-world applications across a wide range of fields, including healthcare, education, and psychological support.

A study conducted at Srinakharinwirot University in Thailand (Hongratanaworakit, T. et al., 2004, published in Phytotherapy Research) found that inhalation of ylang-ylang aroma resulted in decreased heart rate and blood pressure, indicating a significant relaxation effect. Following these findings, ylang-ylang has increasingly been used to support individuals experiencing stress and anxiety.

Research from the Medical University of Vienna in Austria (Lehrner, J. et al., 2005, published in Physiology & Behavior) demonstrated that exposure to orange scent reduced anxiety levels in patients undergoing dental treatment. The study showed a significant decrease in heart rate, suggesting reduced stress during medical procedures. These results encouraged the introduction of scent-based interventions in clinical environments.

Further research at Ruhr University Bochum in Germany (Hongratanaworakit, T. et al., 2006, published in Planta Medica) reported that inhalation of sandalwood aroma shortened sleep onset time and promoted deeper sleep. This finding has been widely recognized as a supportive approach for individuals suffering from sleep disturbances related to stress.

In the United Kingdom, a study conducted at Northumbria University (Moss, M. et al., 2008, published in the International Journal of Neuroscience) demonstrated that peppermint aroma improved attention and memory performance. As a result, educational settings began exploring the use of peppermint scent to enhance learning efficiency and academic performance.

As these studies illustrate, scent has proven to be a practical and effective tool across diverse fields such as medicine, welfare, and education. Its applications continue to expand, highlighting the growing social and therapeutic significance of aromatic interventions.

Practical Uses of Scent and Applications in Healthcare Settings

Numerous studies have shown that incorporating scent into daily life can help restore balance to both the mind and body, particularly during periods of stress or tension.

For example, using scents such as ylang-ylang or lavender in a bedroom or living space through a diffuser can be especially effective. When used before bedtime, these aromas may enhance relaxation and improve the quality of sleep. Simple practices—such as reading quietly or listening to soft music while a diffuser is in use—can further support a restful sleep environment.

In situations where tension rises outside the home, such as at work or while traveling, portable aroma sprays containing orange or bergamot can be helpful. Their compact size makes them easy to carry, allowing for quick emotional refreshment whenever needed.

When the goal is to maintain or increase concentration, peppermint scent has been shown to be particularly effective. Placing a small diffuser near a desk, or lightly scenting a tissue and keeping it nearby, may support improved attention and work efficiency.

On nights when falling asleep feels difficult, oil massage or bathing with sandalwood aroma is often recommended. Adding a few drops to bathwater, or blending the oil into a body cream for gentle massage, can help release physical tension and guide the body toward a calmer, more restful sleep.

On mornings marked by low mood or lack of energy, citrus scents such as lemon or grapefruit can provide a gentle emotional lift. Incorporating these aromas into a morning routine may help set a more positive tone for the day ahead.

While personal use of scent has become increasingly common, aromatherapy is also gaining recognition in medical and clinical environments. In some healthcare facilities, lavender or orange aromas are used to reduce stress in patients before and after medical procedures. In palliative care settings, peppermint has been introduced to help ease nausea and discomfort in cancer patients. Elderly care facilities have also begun using lavender to support sleep quality and alleviate symptoms associated with dementia. In certain psychosomatic or mental health clinics, bergamot and sandalwood are being explored as complementary approaches for depression and anxiety.

From personal self-care practices to complementary use in healthcare, the potential of scent continues to expand across diverse contexts. As research and practical applications advance, the thoughtful use of aroma is expected to play an increasingly meaningful role in supporting healthier and more balanced ways of living.

Future Directions in Research on the Connection Between Scent and the Brain

While extensive research has already been conducted on the effects of scent on the brain, and a wide range of findings have been reported, many important questions remain unresolved. In particular, further investigation is needed to clarify the precise neural pathways through which scent influences emotion, memory, and cognitive function.

The reasons behind individual differences in responses to scent also remain insufficiently understood. Genetic factors, personal experiences, and cultural background may all play a role in shaping how individuals perceive and respond to aroma. By examining these variables in greater detail, it may become possible to develop more personalized and effective approaches to the use of scent.

In addition, there is a growing need to strengthen clinical evidence regarding the effects of scent on specific medical and psychological conditions. Conditions such as anxiety disorders, depression, and dementia require careful evaluation to determine how aromatic interventions can be safely and effectively incorporated as complementary approaches within healthcare settings. Establishing a solid scientific foundation will be essential for responsible clinical application.

New Developments in Scent Research Through AI Technology

At the same time, recent advances in artificial intelligence (AI) have opened new possibilities for more precise use of scent. Research is underway to develop systems that analyze an individual’s emotional state, physical condition, and stress level in real time, and then automatically recommend aromas best suited to those conditions. If such technologies are successfully implemented, they may enable more accurate and responsive use of scent at the individual level.

As research on scent continues to evolve, the future in which aroma-based health management can be practiced in a more scientific and effective manner across daily life and medical environments is steadily coming into view.

Conclusion: The Future of Mind and Body Shaped by Scent

As we have seen throughout this discussion, scent possesses the ability to act far beyond simple sensory pleasure, exerting deep influence on the brain, as well as on emotional and physical states. With ongoing advances in neuroscience and clinical research, the mechanisms and effects of scent are becoming increasingly clear, positioning aroma not merely as a matter of preference, but as a meaningful element in supporting holistic wellbeing.

From everyday self-care practices to complementary applications in healthcare, the potential of scent is expected to expand even further. As scientific knowledge continues to converge with practical experience, aroma may become an increasingly integral part of daily life, supporting healthier, more balanced, and more harmonious ways of living.

Scientific Evidence (Key Studies and Publications)

The following studies provide scientific evidence for the psychological and physiological effects of scent.

For a deeper understanding, readers are encouraged to consult the original publications listed above.