Health & Wellness | By Williams Melwyn | The WFY Magazine | September 2025 Edition
Tulsi and Stress: It lowers cortisol. What the Science Really Says, and How To Use It Safely
If there is one plant that sits at the crossroads of home tradition and modern science in Indian households, it is tulsi. Many of us grew up sipping tulsi tea for coughs, keeping a pot by the veranda, or hearing elders call it “balm for the mind”. Over the past few years, researchers have begun to test those beliefs with clinical tools. The headline finding for many readers is simple: a standardised extract of tulsi, taken twice a day for eight weeks, helped adults under high stress feel significantly calmer and sleep better, and it lowered several laboratory markers linked to the stress response. One trial also measured cortisol in hair, a recognised long-term index of stress biology, and found levels were significantly lower after the intervention than with a dummy capsule.(Frontiers)
This piece explains what that means in plain language, how tulsi may work, who might benefit, who should be cautious, and how to use it in a way that respects both evidence and common sense.
Stress today: why a calmer biology matters
Stress is not simply a feeling. It is a set of biological changes governed by the brain’s stress circuitry, often described as the hypothalamic–pituitary–adrenal axis. This system helps you respond to challenge. When it is switched on too hard, for too long, it is linked with poor sleep, anxious mood, higher blood pressure and a greater load on the heart and blood vessels. That context matters, because stress-related problems are widespread. The World Health Organization estimates that about one in eight people worldwide were living with a mental disorder in 2019, with anxiety and depression the most common. These numbers rose during the pandemic and remain a public health concern.(World Health Organization)
At the same time, many adults are not meeting activity targets that protect the mind and heart. WHO’s latest global analysis indicates that 31 percent of adults were insufficiently active in 2022, roughly 1.8 billion people. Physical inactivity and chronic stress often travel together and can amplify each other.(World Health Organization, The Lancet)
For readers of Indian origin, the cardiovascular link is especially important. Non-communicable diseases account for most deaths in India, and cardiovascular disease is a leading contributor, with a high share of deaths in mid-life. Managing blood pressure, sleep and stress is not optional.(World Health Organization, American College of Cardiology)
Meet tulsi: the plant and the promise
Tulsi (Ocimum tenuiflorum, also called Ocimum sanctum) is a member of the mint family. It has been used in traditional systems for centuries to ease everyday strain, support immunity and help with rest. Modern trials call it an “adaptogen”, a term used for substances that may help the body maintain balance under stress.
A 2022 randomised, double-blind, placebo-controlled trial enrolled 100 adults who rated themselves as stressed and sleeping poorly. Participants took either 125 mg of a standardised tulsi extract twice daily or a matching placebo for eight weeks. Researchers measured outcomes people care about, such as perceived stress and sleep quality, and they also collected laboratory markers including salivary cortisol during an acute stress test, blood pressure responses, and hair cortisol for long-term stress. The tulsi group improved more than the placebo on perceived stress and insomnia scores. Importantly, hair cortisol concentrations at eight weeks were significantly lower with tulsi than with placebo. During a laboratory stress challenge, those taking tulsi had lower salivary cortisol, lower salivary amylase, and smaller rises in blood pressure. The extract was well tolerated.(Frontiers)
Two details from this study help separate hype from reality:
- Meaningful change you can feel: people taking tulsi reported a 37 percent drop in perceived stress scores from baseline to week eight, compared with a 19 percent drop on placebo. The difference matters to daily life.(Frontiers)
- Evidence that biology moved in the same direction: hair cortisol sampled at week eight was significantly lower in the tulsi group than in the placebo group, indicating a quieter long-term stress signal. Acute stress responses were also blunted.(Frontiers)
Laboratory work helps explain why. Pre-clinical studies suggest tulsi can influence stress signalling in the brain, including the CRF1 pathway, which is part of the body’s alarm system. Anti-inflammatory and antioxidant actions have also been observed, which may protect brain regions involved in mood and sleep. While animal findings never translate perfectly to people, they support the idea that tulsi can affect core stress biology.(ResearchGate)
Beyond a single trial, a 2017 review of human studies found favourable results for tulsi across anxiety, stress and metabolic outcomes, with a good safety profile in the short term. The field still needs larger, longer and independent studies, but the direction is encouraging.(PMC, PubMed)
The number everyone asks about: “by how much does it lower cortisol?”
You may have seen claims that tulsi “cuts cortisol by about a third”. Here is the careful version. In the randomised trial above, hair cortisol at week eight was significantly lower in the tulsi group than in the placebo group. The paper reports the actual group values rather than a single percentage headline. It also shows a 37 percent reduction in perceived stress on a standard questionnaire in the tulsi group, which is where many round-number summaries likely come from. The take-home point is that both subjective and objective measures moved in the right direction under controlled conditions.(Frontiers)
Who might benefit
Tulsi is not a tranquilliser, and it is not a cure-all. It may suit adults who recognise a persistent pattern of stress, poor sleep quality and an overcharged response to daily hassles. People who prefer a gentle, plant-based option to combine with lifestyle changes often consider tulsi first.
The strongest evidence at present is for short-term use over eight weeks of a standardised extract in adults reporting high stress and poor sleep, with benefits across perceived stress, sleep quality scores, hair cortisol and acute stress responses.(Frontiers)
How tulsi may work: a simple map
Think of stress control as three linked layers.
- The brain’s alarm switch: tulsi appears to moderate signalling in circuits that trigger the stress response, which may reduce the size of the cortisol surge during challenges.(ResearchGate)
- Body-level responses: under stress, the body raises heart rate, blood pressure and stress enzymes such as salivary amylase. Tulsi users in the trial had smaller bumps in these markers during a lab stressor.(Frontiers)
- Long-run set point: hair cortisol changes suggest the average “idling speed” of the stress system may come down after consistent intake, which fits with calmer days and better sleep.(Frontiers)
Forms, dose and how to use it well
What to look for: If you want to mirror the trial conditions, choose a standardised tulsi extract that clearly lists the tulsi species (Ocimum tenuiflorum or O. sanctum), the extract type and the amount per capsule. The clinical trial used 125 mg, twice daily, for eight weeks. This is not a brand endorsement; it is simply the regimen that has undergone controlled testing.(Frontiers)
How to start:
- Begin with one capsule daily for a few days to check tolerance, then move to twice daily.
- Take with food and a full glass of water.
- Keep a simple log of sleep quality and daytime calm to see whether you are responding.
Traditional forms: Tulsi tea, fresh leaves and culinary use are pleasant and safe for most people. These forms usually deliver smaller, variable amounts of active compounds. They may support wellbeing but should not be expected to reproduce trial-level effects.
Duration: Evidence for benefits comes from eight weeks of use. Safety beyond this window has not been studied in depth. It is sensible to take a break and reassess with your clinician if you plan to continue.(Merck Manuals)
Safety first: who should avoid or take advice
Most adults tolerate tulsi well in the short term, though mild nausea can occur. A few groups should avoid self-prescribing or seek medical guidance:
- Pregnant women, those trying to conceive, and breastfeeding mothers: safety is not established. Animal data raise concerns about effects on implantation at high doses. Until human data are clearer, avoid use.(Merck Manuals, MSD Manuals)
- People on blood thinners or with bleeding risks: some sources caution that holy basil may slow clotting. Stop at least two weeks before planned surgery and review with your doctor if you take anticoagulants or antiplatelet medicines.(RxList, health.osu.edu)
- People with diabetes on medication: tulsi can modestly lower blood sugar in some contexts. If you already take glucose-lowering drugs, monitor closely and discuss dose adjustments with your clinician.(PMC)
- People on sedatives: pre-clinical work suggests additive calming effects are possible. Review combinations with your prescriber.(News-Medical)
- Children: there is not enough evidence for routine use.
Always purchase from a reputable company, ideally with third-party quality testing. Supplements are not regulated as medicines, so label accuracy varies.(Verywell Health)
Make the most of tulsi: stack it with habits that work
Tulsi is not a free pass to keep poor routines. Combine it with simple foundations that have a strong evidence base:
- Move most days: aim for at least 150 minutes of moderate activity each week, plus two sessions of strength work. Given that a third of adults are inactive, any increase helps.(World Health Organization)
- Sleep on schedule: keep a steady sleep–wake time and reduce blue-light exposure in the last hour. The tulsi trial found improved insomnia scores; good sleep habits magnify those gains.(Frontiers)
- Protect your heart: check blood pressure, lipids and fasting glucose regularly, especially if you have a family history or South Asian risk factors.(World Health Organization)
- Practise a daily calm ritual: five to ten minutes of slow breathing, prayer or mindfulness can reduce perceived stress and improve sleep quality in its own right. Use tulsi tea as the anchor for that routine if you like the taste.
A practical week-by-week plan
Week 1:
Start with one 125 mg capsule after breakfast for three days, then move to 125 mg twice daily with meals. Begin a two-line daily log: “energy today” and “sleep quality last night” on a 1–10 scale.
Weeks 2–4:
Add 20–30 minutes of brisk walking five days a week. Keep caffeine earlier in the day. If you use tulsi tea, enjoy a cup in the evening as part of wind-down, but count the capsule as your tested dose.
Weeks 5–8:
Review your log. Many people notice steadier mornings and fewer wake-ups at night. If you track blood pressure at home, note a pre- and post-programme average at the same time of day. If you do not see any change by week 6, tulsi may not be your tool.
Week 9:
Pause for two weeks, then decide with your clinician whether to repeat a cycle, switch to tea only, or stop.
What still needs research
The field is moving, yet several questions remain. Independent trials from multiple centres will help confirm the size of benefit and identify who responds best. The 2022 study used one extract and a single dose; different preparations may not behave the same way. Longer follow-up would show whether improvements persist and whether there are rare side effects with extended use. Objective sleep measures beyond consumer wearables will give clearer answers on sleep architecture.(Frontiers)
The bottom line
Tulsi is more than a comforting herb. A well-designed clinical trial shows that a standardised tulsi extract, taken for eight weeks, can reduce perceived stress, improve insomnia scores, quieten the cortisol surge during acute stress and lower long-term cortisol measured in hair. The results line up with what so many families have intuited for generations, and they do so without dramatic side effects in the short term. It is not a substitute for medical care, nor is it a reason to ignore sleep, movement and nutrition. Used with care, it can be one part of a broader plan to tame modern stress and protect heart and mind.(Frontiers, ResearchGate, PMC)
References and sources for readers who want to go deeper
- Randomised controlled trial of Ocimum tenuiflorum in stressed adults with sleep complaints: outcomes on perceived stress, insomnia, hair cortisol and acute stress responses. Frontiers in Nutrition, 2022.(Frontiers)
- Pre-clinical evidence for stress-pathway modulation by tulsi. PLOS ONE.(ResearchGate)
- Reviews of tulsi’s human evidence base and safety.(PMC, PubMed)
- WHO data on mental health and physical inactivity burden.(World Health Organization)
- WHO and professional summaries on cardiovascular risk in India.(World Health Organization, American College of Cardiology)
- Safety notes on pregnancy, bleeding risk and perioperative advice.(Merck Manuals, RxList, MSD Manuals)
Disclaimer: This article is for general information and education. It is not a substitute for personal medical advice, diagnosis or treatment. Always speak with a qualified health professional before starting any supplement, changing prescribed medicines or making major changes to your diet and exercise routine, especially if you are pregnant, planning pregnancy, breastfeeding, on blood thinners or diabetes medication, or living with a long-term condition.