Quick Takes 🌿

🐱 Cat Alert: Most essential oils are toxic to cats, because cats lack an enzyme that normally detoxifies phenolic compounds. Unsafe oils include lavender, rosemary, rose, cinnamon, peppermint, sage, tea tree, and citrus. If you have feline friends, you’ll have to take precautions.

That said, phenolic compounds from several plants offer significant health benefits:

🧠 Brain Boost: Rose essential oil (inhaled) for just one month increased gray matter volume in healthy women's brains, particularly in regions linked to dementia prevention.

💤 Sleep Helper: Lavender essential oil helps sleep; research on capsules show that it does so by reducing anxiety.

⚡ Memory Enhancer: Rosemary's 1,8-cineole compound crosses the blood-brain barrier; higher blood levels result in faster, more accurate thinking.

Actually scent “training” with a variety of scents boosts memory and cognition significantly. What’s more, it is possible that all sensory training helps optimize cognition, but details on hearing, vision, taste, and sensory integration will be in next week’s newsletter 😉 

And one more caveat:

⚠️ Air Quality Concern: Aerosolizing oils (eg. by using certain essential oil diffusers) impairs air quality and produces particulate matter and volatile organic compounds (VOCs). In some studies, these directly impaired participants’ response inhibition and memory, potentially making decisions more impulsive.

Favorite Finds

1. Alternatives to inhaling scents involve tea and capsules. Several have been shown to be effective.

2. For use outside the home, explore the world of aromatherapy lockets and patches.

I didn’t really want to start a new disposable item habit, so I looked into the option of using a locket or small perfume bottle (there are many options on Etsy), and tucking in a small piece of yarn or cotton/linen fabric that you can refresh as needed. Or you can create a small fabric pouch where you can insert a small scented piece of fabric that you can pin to your clothing.

ConsumerLab reviewed some essential oils recently and gave high grades to Aura Cacia, NOW, and Mountain Rose Herbs, as well as Vitacost and Whole Foods Brand 365..

3. If you don’t have pets and instead want the aroma in your home, choose a passive diffuser. There are a number of options, from lava and other stones to terra cotta options or wood diffusers such as the vörda (but don’t believe their claim that certain oils are safe for pets). There are also reed diffusers, with many companies trying to be sustainable and eco-friendly.

Tea Focus: Organic Peppermint ☕

The Netzler & Lovell study participants used 200mL of peppermint tea (about 6.7 oz) and experienced cognitive benefits within 20 minutes. But note: peppermint lowers women’s testosterone, though may increase men’s.

My favorite source: Rishi Organic Peppermint Tea

(it probably doesn’t work to soothe your digestive system, by the way… some old myths live on)

Simple Recipe:

• 1-2 tsp organic dried peppermint leaves

• 200mL (just under 1 cup) boiling water (208°F and 212°F)

• Steep at least 5 minutes (my sources tell me it will not become bitter if you leave it steeping longer)

• Drink 20 minutes before tasks requiring focus

If you grow your own peppermint

• Harvest just before flowering in late spring when essential oils are at peak levels. 

• Pick in late morning after dew evaporates but before the day's heat diminishes the oils

• Cut stem tips just above where two leaves join - this encourages bushier growth for future harvests 

• Avoid washing if possible since essential oils are water-soluble and washing decreases aroma intensity. If leaves are dirty, rinse quickly with cold water and gently dab dry with a kitchen towel

• Best Drying Methods 🍃

  • Air Drying (Most Flavorful):

    • Spread leaves in single layer in dark place at room temperature, with good airflow. Takes 1-5 days until leaves break easily in fingers

Rosemary Water 🌿

• 2-3 fresh rosemary sprigs (or 1 tbsp dried)

• 2 cups water

• Simmer gently 10-15 minutes

• Strain and cool

Rose Oil 🌹

The study showing gray matter growth used "aroma seals" - essentially small patches or stickers with essential oil that participants wore on clothing.

DIY Rose Aroma Patches:

• Small fabric squares (cotton, felt)

• 1-2 drops rose essential oil OR rose absolute (less expensive)

• Pin to clothing or keep in pocket

• Refresh every few days

  OR

• Two small circles of cotton

• Sew edges together, leaving small opening

• Drop oil on inner fabric, seal opening

• Pin or clip to clothing

Deep Dive: The Science of Scent 🔬

I found reasonable randomized controlled trial evidence for several claims. Note that in many cases, while they randomized the “control” and “exposure” groups, participants are aware whether they are on the essential oil or the placebo, because they can smell the difference. We need more trials comparing different scents.

The strongest evidence is for enhancing cognition, mood, pain, and alertness.

However, essential oils pose two sometimes difficult problems:
1. The very components that make essential oil helpful for humans is toxic to pets, especially cats; safe alternatives mainly involve forsaking aromatherapy (unless away from home) and instead using oral versions that also offer health benefits

2. Diffusers that aerosolize oil into the air negatively impact air quality; safe alternatives include passive diffusers, and scented fabric patches and lockets.

Enhanced Memory & Cognitive Performance 🧠

Specific essential oils can measurably improve cognitive function. Rosemary's 1,8-cineole component crosses the blood-brain barrier and correlates directly with improved performance - higher blood concentrations mean faster, more accurate thinking on memory tasks. Sage species consistently enhance secondary memory and attention accuracy across multiple controlled trials, while peppermint improves working memory, attention, and reduces mental fatigue (Kennedy et al.; Lopresti; Netzler & Lovell).

I recommend avoiding lavender essential oils if memory is a major issue (Moss  et al, 2003). Lavender shows signs of slightly decreasing memory.

Your Options:

• Rosemary, sage, or peppermint essential oil in passive diffusers, fabric patches and lockets

• Cat-safe version: Drink rosemary, peppermint or sage tea (200mL, 20 minutes before tasks)

Better Sleep Quality 😴

Lavender essential oil produces remarkable sleep improvements in clinical settings. Liu et al. (2025) found that 10% lavender oil delivered via nasal patches increased total sleep time by 30 minutes, deep sleep by 28 minutes, and prevented severe complications like psychosis in patients recovering from brain surgery. Effects were strongest in women and appeared within days of starting treatment.

In meta-analyses of published clinical trials, lavender essential oil improves sleep quality in a variety of subjects, from college students to elderly people (Her et al., 2021). Oral lavender essential oil in the form of Silexan reduces anxiety and can have positive effects on sleep as a consequence (Seifritz et al., 2022). While the effect is small (42% of lavender users vs. 35% of placebo), it was comparable to benzodiazepines without causing drowsiness and without potential for abuse (Woelk and Schläfke, 2010). The proper dose of Silexan is 80-160 mg daily.

Other essential oils were also found to have positive effects on sleep, including cinnamon, bergamot, and rosemary (Sivamaruthi et al,. 2025).

Your Options:

• Lavender reed diffusers in bedroom, fabric patches on nightclothes or bedding, or even using a cotton ball with lavender essential oil (2 drops is a reasonable amount). In the studies people smelled these 2-30 minutes, either once or multiple times a day (Donelli et al, 2019).

• Cat-safe: Use oral lavender oil such as Silexan

An Important Supportive Role
Lavender oil can also reduce the depression that sometimes comes with anxiety, and some accompanying symptoms like headache, body aches, and fatigue (Dold et al, 2023).

Lavender aromatherapy had a significant impact on post-herpetic pain (nice to know, though I don’t wish shingles pain on anyone) (You et al, 2024). Lavender oil can also be used topically for other forms of acute pain.

In cancer care, clinical trials of aromatherapy or polyphenolic herbal teas rarely report direct effects on disease progression or survival; endpoints are almost always supportive, related to quality of life, pain, anxiety, or sleep, where many benefits have been identified (Boehm et al; 2012; Corasanitini et al., 2023, Cheng et al., 2022).

Structural Brain Benefits 🧠

Kokubun et al. (2024) demonstrated that one month of daily rose oil inhalation increased gray matter volume in healthy women's brains, particularly in the posterior cingulate cortex - a region where volume loss predicts Alzheimer's progression. This suggests potential long-term neuroprotective benefits.

Rosa damascena extract capsules improved the sexual function of menopausal women and also men with erectile dysfunction but the problem is finding these capsules (Gholinezhad et al., 2025). Consuming rose essential oil does NOT appear safe, so we will have to wait on this one until someone introduces a clinical grade supplement in the US.

Your Options:

• Rose essential oil possibly with on aromatherapy jewelry is a good strategy; ideally steam-distilled and not solvent-extracted

• Cat-safe: Grow roses and spend time visiting them in season! Wear rose-scented fabric patches only outside the home, hang a locket in the car.

Acute Alertness & Focus ⚡

Peppermint shows rapid cognitive benefits across multiple delivery methods. Six-hour exposure via skin patches improved attention and memory, while oral consumption enhanced demanding cognitive tasks within one hour. The effects appear dose-dependent and seem to work through cholinergic system modulation (Hoult et al., 2019; Kennedy et al.).

Your Options:

• Peppermint oil in a passive diffuser or other aromatherapy options are very accessible.

• Cat-safe: You can use peppermint tea

• Peppermint patches or aromatherapy jewelry maybe a good choice for the car, where you want to be alert! Now this is quite different than air fresheners usually made from highly toxic ingredients.

More on Critical Safety Considerations ⚠️

Diffuser Air Quality Issues:

Schwartz-Narbonne et al. (2021) revealed that essential oil diffusers release particulate matter and VOCs that can impair response inhibition and memory - potentially making decisions more impulsive. This occurred with both scented and unscented oils, suggesting the problem lies in the aerosol generation rather than the scents themselves.

Details on Feline Toxicity:

Cats lack the UDP-glucuronosyl transferase 1A6 enzyme (UGT1A6) needed to detoxify phenolic compounds in essential oils. This makes ALL essential oils mentioned potentially toxic to cats, with symptoms developing within 2-12 hours of exposure.

In the Hopefully Not Too Distant Future

Essential oils modulate immune cells, immune system communication, and cell maturation balance in preclinical settings (test tubes and animal models) and show anti-inflammatory and antioxidant effects—but there is very little direct human research on clinical immune or autoimmune outcomes. There is much excitement at what we may yet discover.

References

Addie DD, Boucraut-Baralon C, Egberink H, Frymus T, Gruffydd-Jones T, Hartmann K, Horzinek MC, Hosie MJ, Lloret A, Lutz H, Marsilio F, Pennisi MG, Radford AD, Thiry E, Truyen U, Möstl K; European Advisory Board on Cat Diseases. Disinfectant choices in veterinary practices, shelters and households: ABCD guidelines on safe and effective disinfection for feline environments. J Feline Med Surg. 2015

Boehm K, Büssing A, Ostermann T. Aromatherapy as an adjuvant treatment in cancer care--a descriptive systematic review. Afr J Tradit Complement Altern Med. 2012

Cheng H, Lin L, Wang S, Zhang Y, Liu T, Yuan Y, Chen Q, Tian L. Aromatherapy with single essential oils can significantly improve the sleep quality of cancer patients: a meta-analysis. BMC Complement Med Ther. 2022

Corasaniti MT, Bagetta G, Morrone LA, Tonin P, Hamamura K, Hayashi T, Guida F, Maione S, Scuteri D. Efficacy of Essential Oils in Relieving Cancer Pain: A Systematic Review and Meta-Analysis. Int J Mol Sci. 2023

Dold, M., Bartova, L., Volz, H. P., Seifritz, E., Möller, H. J., Schläfke, S., & Kasper, S. (2023). Efficacy of Silexan in patients with anxiety disorders: a meta-analysis of randomized, placebo-controlled trials. European Archives of Psychiatry and Clinical Neuroscience

Donelli, D., Antonelli, M., Bellinazzi, C., Gensini, G. F., & Firenzuoli, F. (2019). Effects of lavender on anxiety: A systematic review and meta-analysis. Phytomedicine, 65, 153099.

Du, B., Schwartz-Narbonne, H., Tandoc, M., Heffernan, E. M., Mack, M. L., & Siegel, J. A. (2022). The impact of emissions from an essential oil diffuser on cognitive performance. Indoor Air

Gholinezhad, Z., Karimi, F. Z., Rakhshandeh, H., & Mazloum, S. R. (2025). Impact of Rosa damascena extract capsule on the sexual function of menopausal women: A randomized clinical trial. Explore (NY)

Hackländer, R., Baess, P., & Bermeitinger, C. (2025). Smells like … no evidence that odors influence the attentional blink. Attention, Perception, & Psychophysics

Her, J., & Cho, M. K. (2021). Effect of aromatherapy on sleep quality of adults and elderly people: A systematic literature review and meta-analysis. Complementary Therapies in Medicine

Hoult, L., Longstaff, L., & Moss, M. (2019). Prolonged Low-Level Exposure to the Aroma of Peppermint Essential Oil Enhances Aspects of Cognition and Mood in Healthy Adults. American Journal of Plant Sciences

Kennedy, D. O., Okello, E., Chazot, P. L., Howes, M. J. R., Moss, M., & Wightman, E. L. (2018). Volatile Terpenes and Brain Function: Investigation of the Cognitive and Mood Effects of Mentha × Piperita L. Essential Oil With In Vitro Properties Relevant to Central Nervous System Function. Nutrients

Kikukawa, H., Koura, S., Kuge, M., Miwa, K., & Yao, M. (2021). Effects of Aromatherapy of Himekuromoji (Lindera lancea), Essential Oil on Vital and Stress, Emotion and Cognitive Function of the Elderly in Need of Care. Open Journal of Therapy and Rehabilitation

Kokubun K, Nemoto K, Yamakawa Y. Continuous inhalation of essential oil increases gray matter volume. Brain Research Bulletin. 2024

Liu, Y., Dong, Y., Wang, X., Huang, Y., Wu, F., Xia, F., Bai, H., Li, H., Shi, L., & Wang, B. (2025). Effects of lavender essential oil inhalation aromatherapy on postoperative sleep quality in patients with intracranial tumors: a randomized controlled trial. Frontiers in Pharmacology

Lopresti AL. "Salvia (Sage): A Review of its Potential Cognitive-Enhancing and Protective Effects." Drugs R D. 2017

Moss, M., Cook, J., Wesnes, K., & Duckett, P. (2003). Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. International Journal of Neuroscience, 113(1), 15-38.

Moss, M., & Oliver, L. (2012). Plasma 1,8-cineole Correlates with Cognitive Performance Following Exposure to Rosemary Essential Oil Aroma. Therapeutic Advances in Psychopharmacology, 2(3), 103-113.

Netzler, E., & Lovell, B. (2025). A Randomized Placebo‐Controlled Clinical Trial Exploring the Short‐Term Cognitive and Cerebrovascular Effects of Consuming Peppermint Tea. Published in: Human Psychopharmacology: Clinical and Experimental

Seifritz, E., Kasper, S., Möller, H. J., Volz, H. P., Müller, W. E., Eckert, A., & Hatzinger, M. (2022). Effect of anxiolytic drug silexan on sleep - a narrative review. World Journal of Biological Psychiatry.

Sharifi-Rad, J., Quispe, C., Kumar, M., Akram, M., Amin, M., Iqbal, M., Koirala, N., Sytar, O., Kregiel, D., Nicola, S., Ertani, A., Victoriano, M., Khosravi-Dehaghi, N., Martorell, M., Alshehri, M. M., Butnariu, M., Pentea, M., Rotariu, L. S., Calina, D., Cruz-Martins, N., & Cho, W. C. (2022). Hyssopus Essential Oil: An Update of Its Phytochemistry, Biological Activities, and Safety Profile. Oxidative Medicine and Cellular Longevity, 2022, Article ID 8442734.

Sivamaruthi, B. S., Kesika, P., Sisubalan, N., & Chaiyasut, C. (2025). The Role of Essential Oils on Sleep Quality and Other Sleep-related Issues: Evidence from Clinical Trials. Mini Reviews in Medicinal Chemistry.

Woelk, H., & Schläfke, S. (2010). A multi-center, double-blind, randomised study of the Lavender oil preparation Silexan in comparison to Lorazepam for generalized anxiety disorder. Phytomedicine

You, J., Shin, Y. K., & Seol, G. H. (2024). Alleviating effect of lavender (Lavandula angustifolia) and its major components on postherpetic pain: a randomized blinded controlled trial. BMC Complementary Medicine and Therapies