Quick Takeaway
Ginseng’s effects on the brain aren’t linear—it follows a U-shaped response. A small dose may boost alertness, a moderate amount can actually promote sleep, while too much may lead to overstimulation again! This phenomenon has a scientific name: biphasic dose response, also known as hormesis.
Same herb, different dose, totally different effect! And don’t forget to check: is it a human study, animal model, or just a petri dish?
| Dose | What Was Observed | References and Evidence Grading |
|---|---|---|
| 200–400 mg of G115® per day or 0.5–2 g of raw herb (based on human studies) | Enhances attention and mental arithmetic performance, and reduces fatigue (using standardized G115® extract) | Reay JL, 2005Design: Randomized, double-blind, crossover trial Level of Evidence: Moderate to High |
| 4.5 g of red ginseng per day for 2 consecutive weeks (based on human studies) | Increases deep sleep duration (Stage 3), reduces light sleep (Stage 2), and promotes sleep onset. | Lee SA, 2010Design: Small-scale randomized controlled trial Level of Evidence: Moderate |
| Red ginseng extract at 10–200 mg/kg (animal study, rats) | Increases non-rapid eye movement (NREM) sleep and total sleep time, potentially associated with changes in GABA_A receptor activity. | Lee CI, 2012Model: Animal study Level of Evidence: Low to Moderate |
| 200 mg to 3 g of raw herb per day, for up to 12 weeks (based on clinical observations and reports) | May cause adverse effects such as insomnia, irritability, palpitations, and elevated blood pressure. | WebMDSource: Expert consensus and user-reported experiences Level of Evidence: Low |
What’s Going On? Ginseng’s Two-Sided Compounds Explained
Isn’t it fascinating? How can the same ginseng produce such different effects depending on how much you take? The answer lies in its active compounds—such as Rg1, Rh1, Rb1, and Rd—which are some of the key bioactive ingredients in ginseng.
- Rg1 / Rh1 (Low Dose): It’s like having a cup of invigorating tea in the morning—these compounds help wake up your brain, boost alertness, and sharpen focus. They’re especially suitable for busy mornings or study sessions when you need to stay mentally sharp.
- Rb1 / Rd (Moderate Dose): These are more like a warm glass of milk before bed—they help your brain produce GABA, a calming neurotransmitter that promotes relaxation, reduces stress, and makes it easier to fall asleep.
Ginseng feels like it’s playing double duty—your morning boost and your bedtime calm, all in one!
Other ways ginseng may work include:
- Mild enhancement of NMDA and 5-HT1A receptor activity (associated with improved learning and concentration)
- At moderate doses, it acts on GABA_A and adenosine A1 receptors, leading to reduced neural activity and producing a sedative effect.
- At high doses, it activates the hypothalamic-pituitary-adrenal (HPA) axis, which may lead to increased stress responses, including irritability and insomnia.
So, what did Calabrese’s review reveal?
Let’s take a look at what the Calabrese systematic review has to say.
Over 90% of ginseng-related studies have shown that low doses are the most effective, while increasing the dose often leads to reduced effectiveness or even opposite (adverse) effects.
Findings from the Calabrese Systematic Review
Please consult a certified TCM practitioner before using ginseng. This content is not a substitute for professional medical advice.
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