#stress #essential_oil #physiological #psychology Second-Hand Stress: Neurobiological Evidence for a Human Alarm Pheromone https://www.nature.com/articles/npre.2008.2561.1 ## **🧠 Human Alarm Pheromones – 1 Page Summary** ### **👃 What Was Studied:** Can humans detect ‘stress sweat’ from others, and does it affect their brain and behavior, even if they can’t smell it consciously? --- ### **🔬 What They Did:** - Collected sweat from people skydiving (emotional stress) and from runners (exercise control). - Gave sweat samples to unrelated people while scanning their brains (fMRI). - Tested whether sweat influenced perception of threatening faces. --- ### **🧠 What They Found:** - Stress sweat activated the amygdala (emotion center) more than exercise sweat. - Participants couldn’t consciously tell the difference in smell. - Stress sweat made people better at detecting subtle threat in faces. --- ### **💡 What It Means:** Our brains pick up on emotional signals through scent, even when we don’t know it. It acts like a hidden ‘alarm pheromone’ system, preparing us for possible danger. --- ### **🌿 Why It Matters:** This suggests that essential oils like lemongrass might not only mask smells but actually reduce the brain’s unconscious stress reaction — creating a calming, emotionally safer space. --- ### **📘 Citation:** Mujica-Parodi et al. (2009). _Second-Hand Stress: Neurobiological Evidence for a Human Alarm Pheromone_. ---- Research on second-hand stress from sweat involves the concept of "alarm pheromones," which are chemical signals that can be detected through olfaction and influence emotional responses. Studies have explored how inhaling sweat collected from individuals under stress affects neural activity and emotional perception in others. ### Key Findings 1. **Neural Response to Stress Sweat**: Studies using fMRI have shown that inhaling stress sweat activates the amygdala, a brain region associated with emotional processing, even when the sweat odors are indistinguishable from those collected during non-stress conditions like exercise[3][4]. This suggests that the response is not due to the odor itself but to the emotional content it conveys. 2. **Enhanced Emotional Processing**: Inhaling stress sweat enhances the neural response to neutral and ambiguous facial expressions, increasing the late positive potential (LPP) in EEG recordings. This indicates that stress sweat can heighten the salience of biologically relevant stimuli, making neutral faces appear more threatening or significant[1]. 3. **Behavioral Implications**: Exposure to stress sweat can affect threat perception, making individuals more vigilant or reactive to potential threats. This is demonstrated by increased startle responses and altered perception of facial expressions[1][3]. 4. **Sweat Collection and Analysis**: Recent advancements include the development of wearable sensors for detecting cortisol levels in sweat, which can provide real-time monitoring of stress levels[2][5]. These technologies aim to quantify stress more objectively than traditional self-reported measures. ### MRI and fMRI Studies - **Amygdala Activation**: fMRI studies have consistently shown that the amygdala is activated when individuals inhale stress sweat compared to exercise sweat. This activation is linked to emotional arousal rather than olfactory processing[3][4]. - **Neurobiological Evidence**: The activation of the amygdala in response to stress sweat supports the concept of a human alarm pheromone, which can modulate emotional states and threat perception[3][4]. These studies collectively suggest that sweat can convey stress signals that influence emotional processing in others, even when the odors are not consciously distinguishable. This phenomenon highlights the complex interplay between chemical cues and emotional states in humans. Citations: [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC3277367/ [2] https://www.nature.com/articles/s41528-024-00333-z [3] https://www.nature.com/articles/npre.2008.2561.1 [4] https://www.nature.com/articles/npre.2008.2561.1.pdf [5] https://www.nature.com/articles/s41467-021-22109-z [6] https://hdiac.dtic.mil/articles/analytical-identification-of-stress-odors-from-human-breath/ [7] https://pmc.ncbi.nlm.nih.gov/articles/PMC3782473/ [8] https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0272247 [9] https://pmc.ncbi.nlm.nih.gov/articles/PMC7209933/ [10] https://d-nb.info/1229328661/34 [11] https://edition.cnn.com/2009/HEALTH/08/19/stress.sweat.smell.pheromones/index.html [12] https://www.mdpi.com/2673-4532/3/2/13 [13] https://academic.oup.com/chemse/article/42/8/663/4080195 [14] https://journals.physiology.org/doi/full/10.1152/jn.00601.2015 [15] https://journals.sagepub.com/doi/full/10.1177/0956797620970548 [16] https://repository.lsu.edu/cgi/viewcontent.cgi?article=5256&context=gradschool_dissertations [17] https://www.orlandohealth.com/content-hub/secondhand-stress-how-people-around-you-can-increase-your-anxiety/ [18] https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0006415 [19] https://pmc.ncbi.nlm.nih.gov/articles/PMC8726592/ [20] https://www.tandfonline.com/doi/full/10.4155/bio.15.229 [21] https://onlinelibrary.wiley.com/doi/full/10.1002/brb3.2956 [22] https://www.frontiersin.org/journals/systems-neuroscience/articles/10.3389/fnsys.2013.00066/full [23] https://www.linxens.com/en/insight-hub/sweat-analysis-using-wearable-medical-devices-reveals-a-wealth-of-health-information [24] https://academic.oup.com/scan/article/7/2/208/1624499 [25] https://www.nature.com/articles/s41598-024-68250-9 [26] https://pmc.ncbi.nlm.nih.gov/articles/PMC7011725/ [27] https://healthcare-in-europe.com/en/news/sweat-analysis-wearables-health-information.html [28] https://journals.sagepub.com/doi/10.1177/0956797620970548?icid=int.sj-full-text.similar-articles.4 [29] https://techfinder.stanford.edu/technology/mass-spectrometry-imaging-enhanced-fingerprint-or-sweat-analysis [30] https://pmc.ncbi.nlm.nih.gov/articles/PMC10252040/ --- Answer from Perplexity: pplx.ai/share -- Related https://pubmed.ncbi.nlm.nih.gov/35603047/ https://pubmed.ncbi.nlm.nih.gov/34329669/ ---- Aroma oils can potentially mask or alter the perception of stress-related body odors through several mechanisms: 1. **Masking Odors**: Essential oils like **bergamot**, **lemon eucalyptus**, and **patchouli** have strong, pleasant scents that can mask body odors, including those associated with stress[1][6]. These oils can provide a fresh aroma that overpowers unpleasant odors. 2. **Antimicrobial Properties**: Many essential oils, such as **tea tree** and **sage**, possess antimicrobial properties that can reduce the growth of bacteria and fungi responsible for body odor[6]. By controlling these microorganisms, the oils can help minimize the intensity of body odors. 3. **Psychological Effects**: Aromatherapy with essential oils can influence emotional states and stress perception. Oils like **bergamot** and **lavender** have been shown to reduce stress and anxiety, potentially altering how one perceives body odors[2][5]. This psychological effect can indirectly influence how stress-related body odors are perceived. 4. **Physiological Impact**: Essential oils can affect physiological responses related to stress, such as heart rate and cortisol levels, which might indirectly influence body odor production[2]. However, this is more about managing stress itself rather than directly altering body odor perception. In summary, while aroma oils can mask body odors and potentially reduce stress, their ability to specifically alter the perception of stress-related body odors is more indirect and related to their psychological and antimicrobial effects. Citations: [1] https://blog.simplyearth.com/best-essential-oils-for-eliminating-body-odor/ [2] https://pmc.ncbi.nlm.nih.gov/articles/PMC10180368/ [3] https://healingfragrances.net/blogs/news/the-odor-of-aging-a-shift-towards-essential-oils-for-deodorization-and-well-being [4] https://devotionbeautique.com/prevent-body-odor-bath-oil-treatment/ [5] https://researchrepository.wvu.edu/cgi/viewcontent.cgi?article=12511&context=etd [6] https://www.edensgarden.com/blogs/news/the-top-essential-oils-for-body-odor [7] https://repository.lsu.edu/cgi/viewcontent.cgi?article=5256&context=gradschool_dissertations [8] https://onlinelibrary.wiley.com/doi/10.1111/j.1468-2494.2011.00649.x [9] https://www.webmd.com/skin-problems-and-treatments/ss/slideshow-essential-oils [10] https://pmc.ncbi.nlm.nih.gov/articles/PMC4329734/ [11] https://www.lung.org/blog/essential-oils-harmful-or-helpful [12] https://pmc.ncbi.nlm.nih.gov/articles/PMC6710396/ [13] https://www.jeancoutu.com/en/beauty/beauty-tips/how-to-reduce-stress-sweat/?From=86021 [14] https://www.healthshots.com/beauty/natural-cures/home-remedies-to-get-rid-of-body-odour/ [15] https://www.bathandbodyworks.com.sg/body-care/wellness-and-aromatherapy/all-aromatherapy [16] https://www.healthline.com/health/stress-sweat [17] https://wellaholic.com/blog/underarm-odour/ [18] https://www.reddit.com/r/essentialoils/comments/1dzw3va/which_essential_oils_cut_through_body_odor_best/ [19] https://www.nivea.in/advice/how-to-get-rid-of-body-odor-and-armpit-smell [20] https://nikura.com/blogs/discover/essential-oils-to-eliminate-odour --- Answer from Perplexity: pplx.ai/share --- ## Do calm people give off calming scent? Does the reverse work? Now think of commercial opportunities! haha ![[Pasted image 20250403061349.png]] ![[Pasted image 20250403061529.png]]