New Lion’s Mane Study Reports Modest Gains in Attention, Sleep, and Mood

By Jimmy Daoutis, Founder of AdvancedMycoTech · Last updated: April 2026

Quick summary: A new 2026 medRxiv preprint reports that 2 g/day of Hericium erinaceus fruiting body plus mycelial biomass for eight weeks was associated with modest improvement in one visual attention/working-memory task, plus faster improvement in subjective sleep quality, morning restedness, and mood versus placebo. The study is useful, but not definitive: it has not been peer reviewed, was funded by M2 Ingredients, used a mixed fruiting-body/mycelial-biomass ingredient, and did not show broad improvement across every cognitive measure.

What the New Lion’s Mane Study Found

A new randomized, double-blind, placebo-controlled lion’s mane study is worth paying attention to — carefully. The preprint, posted on medRxiv in April 2026, tested daily Hericium erinaceus supplementation in adults aged 40–75 who reported mild-to-moderate cognitive difficulty. Participants took either lion’s mane or placebo for eight weeks after a baseline period.

The short version: the lion’s mane group improved more than placebo on one computerized task related to visual attention and working memory, and the researchers also reported faster improvement in subjective sleep quality, morning restedness, and mood. No adverse events were reported in the lion’s mane group. Those are meaningful signals, especially because the study was randomized and placebo-controlled.

But this is not a “lion’s mane proves brain boost” moment. The article is currently a preprint, which means it has not completed peer review. The study was funded by M2 Ingredients, the test product was supplied by M2 Ingredients, and the intervention combined fruiting body with mycelial biomass rather than testing a simple fruiting-body-only extract. The result should be framed as promising but preliminary, not settled science.

Evidence strength: Emerging — randomized placebo-controlled design, but preprint status and funding source require caution. Source: Daoust et al., 2026 medRxiv preprint.

Study Design: Who Took What, and for How Long?

The trial enrolled adults aged 40–75 with self-reported concerns about memory, focus, and cognition. Participants completed screening, randomization, a one-week baseline period, and then eight weeks of supplementation or placebo. The primary analysis included 109 participants: 57 in the lion’s mane group and 52 in the placebo group.

The lion’s mane dose was 2 g/day, taken as three capsules daily. Importantly, this was not a pure fruiting-body extract and not a pure mycelium product. The preprint describes the test product as certified organic powdered H. erinaceus containing both fruiting body and mycelial biomass, produced by solid-state fermentation on organic oats, then dehydrated and milled into powder.

That matters for supplement shoppers. Many lion’s mane discussions treat “fruiting body” and “mycelium” as if they are interchangeable. They are not. Fruiting bodies and mycelium can differ in bioactive profiles, and mycelium grown on grain can introduce additional interpretive questions. This study may tell us something about this specific mixed biomass preparation at 2 g/day; it does not automatically prove that every lion’s mane capsule, extract, powder, or blend will do the same thing.

What Researchers Measured

Cognition was measured remotely using computerized BrainHQ tasks, and participants also completed daily subjective assessments related to sleep and wellbeing. The decentralized design makes the study closer to real-world supplement use than a tightly controlled lab visit, but it also introduces more variability: participants complete tasks at home, on their own devices, under conditions researchers cannot fully control.

The preprint also notes that participants had to avoid memory or cognitive-function-targeted supplements and mushroom supplements before randomization. That is a useful design detail because it reduces the chance that another nootropic or mushroom product was driving the results.

The Main Cognitive Result: One Attention Task Improved

The most important cognitive finding was on the Juggle Factor task. According to the preprint, participants receiving lion’s mane showed significantly greater improvement over time than placebo on this task, with a reported linear mixed model p value of 0.001 and a +0.45 z-score change.

That is interesting because Juggle Factor is framed as a visual attention and working-memory task. In plain English, this points more toward “tracking and mentally managing visual information” than toward a broad, all-purpose memory boost.

Just as important: the study did not report significant between-group improvements across all cognitive measures. The preprint says no significant between-group differences were observed for Memory Grid, Target Tracker, Mental Map, Sandia’s Matrices, or composite cognitive scores. There was also an apparent placebo-favoring difference on one reaction-time task in unadjusted analysis, but the authors state that this was not statistically significant after accounting for baseline performance differences and ceiling effects.

That pattern should shape the headline. The fair takeaway is not “lion’s mane improves cognition across the board.” The fair takeaway is: this specific lion’s mane preparation was associated with improvement on one visual attention/working-memory task, while several other cognitive outcomes did not separate from placebo.

Honest assessment: This strengthens the case that lion’s mane may affect certain cognitive domains, but it does not justify blanket claims about memory, IQ, ADHD, dementia prevention, or instant focus.

Sleep, Restedness, and Mood: Promising, but Subjective

The study also reported faster improvement in sleep quality, morning restedness, and mood in the lion’s mane group compared with placebo. These results fit with earlier clinical signals suggesting lion’s mane may influence mood and stress-related outcomes over weeks of daily use.

The caution is that these were subjective daily measures. Subjective sleep quality and restedness matter — if people feel they sleep better and wake more restored, that is a real user-centered outcome. But subjective data can also be influenced by expectancy, daily routine, stress, and other lifestyle factors, even in blinded studies.

This is why the sleep and mood finding is best described as a signal, not proof. It supports further research and may help explain why some users report lion’s mane as “calming” rather than stimulating. But it does not mean lion’s mane treats insomnia, anxiety, depression, or any clinical sleep disorder.

If your main goal is sleep support, see our broader guide to best mushroom supplements for sleep. If your main interest is mood and stress, our lion’s mane and anxiety evidence review breaks down the human trials separately.

Safety: No Adverse Events in the Lion’s Mane Group

The preprint reports no adverse events in participants receiving lion’s mane, while three mild-to-moderate adverse events occurred in the placebo group. That is reassuring for this study population and this eight-week dose.

Still, “no adverse events in one trial” is not the same as “risk-free.” People with mushroom allergies, complex medication regimens, immune conditions, pregnancy, or diagnosed neurological or psychiatric conditions should not treat this as medical clearance. Supplement studies often exclude higher-risk participants, and rare side effects may not appear in a study with 57 people receiving the active product.

For a more cautious review, see our lion’s mane side effects guide. That article covers allergic reactions, digestive issues, medication considerations, and the difference between clinical-trial safety signals and real-world supplement use.

Why the Ingredient Format Matters

This study used a mixed preparation: fruiting body plus mycelial biomass. That detail is easy to skip, but it is one of the most important buyer takeaways.

Lion’s mane contains multiple classes of compounds. Fruiting bodies are commonly discussed for hericenones and beta-glucans. Mycelium is often discussed for erinacines, although commercial mycelium products vary widely depending on cultivation method, grain substrate, and testing transparency. A mixed preparation may expose participants to a broader profile of mushroom-derived compounds, but it also makes the result harder to translate to standard retail products.

For shoppers, the practical question is not just “does lion’s mane work?” It is “which lion’s mane product is actually comparable to the evidence?” A 2 g/day biomass powder trial does not map neatly onto a 500 mg hot-water extract capsule, an 8:1 concentrated extract, or a nootropic stack that includes lion’s mane alongside herbs.

That is why label transparency matters. Look for clear species identification, extraction details, beta-glucan disclosure when available, and third-party quality signals. Our best lion’s mane supplements roundup ranks products based on those practical quality markers rather than hype claims.

How This Fits With Existing Lion’s Mane Research

This preprint does not appear out of nowhere. It fits into a growing but still early body of human lion’s mane research. Prior studies have reported signals for processing speed, stress, mood, anxiety-related outcomes, and cognitive scores in specific populations, while also showing mixed or limited effects depending on the outcome measured.

That mixed pattern is exactly what you would expect from early nutrition research. Lion’s mane is not a pharmaceutical stimulant. It is a complex mushroom ingredient with multiple compounds, different product formats, and likely subtle effects that may depend on age, baseline cognitive status, dose, duration, and preparation quality.

For readers trying to make sense of the broader evidence, start with our evidence review on whether lion’s mane actually works. If your question is timing, our guide to how long lion’s mane takes to work explains why clinical effects usually show up over weeks, not from a single capsule.

What This Means Practically

If you already use lion’s mane, this study is a useful addition to the evidence base — especially if you are using it for attention, subjective cognitive support, sleep quality, or mood. It supports the idea that daily use over eight weeks may matter more than one-off dosing.

If you are considering lion’s mane for the first time, the best interpretation is measured optimism. The new preprint suggests a possible benefit in one visual attention/working-memory task and subjective wellbeing measures, but it does not prove broad cognitive enhancement. It also does not prove that every lion’s mane supplement on the shelf is evidence-equivalent.

A reasonable, evidence-aligned approach is to choose a transparent product, use it consistently, track your own sleep, mood, and focus over 4–8 weeks, and avoid treating it as a substitute for medical care. If you are using it alongside medications or for a diagnosed condition, talk to a qualified healthcare professional first.

For a product-quality starting point, see the AdvancedMycoTech lion’s mane supplement rankings. For a broader cluster overview, read The Complete Guide to Lion’s Mane Mushrooms.

Evidence Strength Assessment

Visual attention / working memory: Emerging — one preprint RCT reported improvement on the Juggle Factor task, but several other cognitive measures did not significantly separate from placebo.
Sleep quality and restedness: Emerging — subjective daily measures improved faster in the lion’s mane group, but objective sleep outcomes should be interpreted cautiously.
Mood: Emerging — positive signal in this preprint, consistent with earlier mood/stress research, but not evidence that lion’s mane treats depression or anxiety disorders.
Safety at 2 g/day for eight weeks: Promising but limited — no adverse events were reported in the lion’s mane group, but the active group included only 57 participants.
Generalizing to all lion’s mane supplements: Limited — the intervention used fruiting body plus mycelial biomass, so results should not be automatically applied to every extract format.

Want a lion’s mane product with clearer quality signals?

Start with products that disclose the mushroom part used, extraction method, and quality testing instead of relying on vague “brain boost” marketing.

See the Best Lion’s Mane Supplements →

FAQ

Does this new study prove lion’s mane improves memory?

No. The study reported improvement on one visual attention/working-memory task, but several other cognitive measures did not show significant between-group differences. It is more accurate to say the study found a specific attention-related signal, not broad proof of memory enhancement.

Was the 2026 lion’s mane study peer reviewed?

Not at the time of this article. It was posted as a medRxiv preprint, which means it should be treated as preliminary until it passes peer review and the methods, analysis, and conclusions are evaluated by independent reviewers.

What dose did the study use?

The study used 2 g/day of Hericium erinaceus fruiting body plus mycelial biomass, taken as three capsules daily for eight weeks. That dose and ingredient format may not be equivalent to every retail lion’s mane extract.

Did participants report side effects?

The preprint reports no adverse events in the lion’s mane group. That is reassuring, but it does not guarantee that lion’s mane is risk-free for every person or every product format.

Should I buy a mycelium product because this study used mycelial biomass?

Not automatically. The study used a specific mixed preparation from one supplier. Shoppers should still evaluate label transparency, testing, extraction method, mushroom part, and whether the product matches their goals.