--- title: I Trained My Brain for 35 Days. The Best Sessions Landed on My Worst Days. slug: mendi-review category: Brain Health datePublished: 2026-06-08 dateModified: 2026-06-08 author: Roy Sañudo S. reviewedBy: Roy Sañudo S. lastReviewed: 2026-06-08 url: https://animacosmi.com/articles/mendi-review --- # I Trained My Brain for 35 Days. The Best Sessions Landed on My Worst Days. An honest 35-day test of the Mendi neurofeedback headset, the brain-training headband that helped me reset on stressful days, wind down in the evening, and focus better over time. A first-hand review of the Mendi neurofeedback headset, after 35 days of testing. I didn't go in chasing a number. My goal was simple: train my focus and see whether a few minutes a day could actually sharpen how my brain works. What I got back was a little more than that, and not quite what I expected. Here is the part I did not expect from five weeks with a brain-training headset. The headset itself is strange enough: it lets you move a ball on a screen with nothing but your concentration. But the real surprise was when it worked best. My best sessions did not come on the calm, easy days. **They came on my most stressful ones**, the days I almost skipped the session entirely. I would sit down tense and worn out, run the ten minutes anyway, and watch the screen post some of my highest scores of the whole month. That surprise, not any single number, is what this review is about. A note before we start: [Mendi](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023) sent me the headset to test as part of a partnership. This was not a paid promotion, they didn't pay me to write it, and the verdict is my own. If you decide to buy through my link at the end, I may earn a small commission, at no extra cost to you. Everything below is my own experience over five weeks, with my own numbers from my health-tracking devices. ==As a reader, you get 27% off with the code [WelcomeRoy](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023)==, and I share the details at the end. ## What Is Mendi, in Plain Terms? [Mendi](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023) is a soft headband you wear on your forehead for a few minutes a day. A small sensor shines harmless light through your skin and reads how much oxygen-rich blood flows to the area right behind your forehead. That spot, just behind your forehead, runs your focus, your calm, and your self-control (scientists call it the prefrontal cortex). That reading drives a simple game on your phone, and this is the part that got me the first time: lock your focus and the ball climbs; let your mind drift and it sinks. No buttons, no hands, just your attention doing the work. For the first time, you can actually see your focus on a screen and learn to steer it. Training a live signal by watching it this way has a name, **neurofeedback**, and the light-reading method behind it, called **fNIRS**, is the same kind hospitals use to study the brain. This is what makes it different from a smartwatch or a fitness ring. Those devices **measure** you. Mendi asks you to **train**. Each short session works the front of your brain on purpose, pulling more blood and oxygen to it, the way one curl works your arm. The idea is that repeating this strengthens your focus over time, the brain's version of building a muscle. Stanford neuroscientist [Dr. Ben Rein](https://www.benrein.com/) has [praised Mendi for bringing brain-imaging technology that used to cost a fortune straight into people's homes](https://www.mendi.io/pages/science). The science here is young, but it is real. In a careful trial at Japan's [Tohoku University](https://doi.org/10.3390/brainsci12010005), the rigorous kind where no one knew who was getting the real training, people who trained at home with the same kind of light-based brain feedback Mendi uses got better at concentrating, and at holding things in mind, than people who trained without it. I won't oversell it, though. The field is young, the strongest studies are still small, and a [2026 trial](https://doi.org/10.64898/2026.04.26.26351764) using a different brain-reading method (EEG), in people with ADHD, found no benefit at all. No large study of this exact headset exists yet. That Tohoku study tested the method, not the Mendi headset itself, but it is the closest solid evidence to what Mendi does, and it is exactly why I ran my own month-long test instead of trusting the marketing. ## My 35-Day Routine I built it up slowly. Weeks one and two: five minutes each morning. Week three: ten minutes. Weeks four and five: twice a day, ten minutes in the morning and ten in the evening. I was not chasing a number. I wanted to know whether a tiny daily habit would hold once life got busy, and what it would change in how I think and feel. Three things changed, in rising order of how much they mattered to me. ## How Do You Calm a Stressful Mind? This is the surprise I opened with. My most stressful days produced my best sessions, again and again. The headset stopped being a productivity gadget and became my reset: ten minutes to step out of a spiral and come back level. It also became my way to switch cleanly from one task to the next, a short pause that clears the last thing before I start the next one. That reset, on the days I needed it most, was the benefit I felt first and trusted most. ## How Do You Quiet a Racing Mind After a Hard Day? A short session in the evening settled the looping thoughts after a hard day and left me readier to switch off. After busy, stressful days my mind kept running, still sorting through everything I had to do, and ten quiet minutes helped me set it down. One honest caveat, because it matters: a bright phone screen right before bed works against sleep, not for it. So I ran these eyes-closed, with the screen dimmed, earlier in the evening rather than as the last thing before lights-out. This is just how I ended up using it, not something Mendi recommends, and I share it as a personal note. But it became one of my favourite ways to use it. ## How Long Does It Take to Improve Your Focus? This was the quietest change and the most honest. I did not feel sharper in week one. The shift only showed up around week four, once the twice-a-day habit held, and even then it was quiet: I got pulled away from hard tasks less often, and I could stick with my work a little longer before my mind wandered. Real, but it builds slowly. That quiet, slow-built focus was the third change, and the one I would have bet against. ## The One Tip I'd Pass to a New User Around day 21 I stopped staring at the ball. I held the phone at eye height, closed my eyes for stretches, and just pictured the ball climbing. My scores jumped and stayed up. My working theory: a head bowed over a phone may pinch the blood flow to the very area you are training, and picturing the movement may wake up parts of the brain that plain staring misses. This became my default for every session afterward, and it is the most useful thing I can hand a new user. ## What Are the Downsides? Two things are worth knowing going in. Sessions come in fixed lengths of five, ten, or fifteen minutes rather than anything you set yourself, though that actually keeps the routine simple. And the big one: this is a slow build, not a quick win. Neither broke the experience for me. They are just the honest fine print. ## Did My Focus Scores Actually Improve? My scores climbed the more I practised. The number I care about most is control time, how long I can hold the ball steady with focus alone, and at my best it reached **85 seconds**, with a top session score of 93. Both peaked in the week I trained most, then eased in a busier week, which only proved the obvious: you get out what you put in. One person, five weeks, so take it as a hint, not proof. ## Who Is Mendi For? If you want a few quiet minutes a day that leave you calmer on a hard day, help you switch cleanly between tasks, and quiet the mental noise after a long one, [Mendi](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023) earns its place. It trains the one part of your brain you lean on most for focus and self-control, and it gives you something most wellness gadgets never do: a clear signal you can actually practise with. It is not a passive tracker and it is not a quick fix. **The value lives in showing up**, and that part is on you. ## Would I Keep Using It? Yes. Mendi suggests it takes about eight weeks and I tested five, so I have only climbed part of the hill. Think of the front of your brain like a muscle: the real, lasting change comes from months of steady reps. Even in five weeks I found genuine, daily use, the stress reset and the calmer evening wind-down, and the [headband](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023) is staying in my rotation precisely because the best part is meant to arrive later. I will publish a longer update in a few months and tell you honestly whether the focus change held, grew, or faded. One last thing I came to appreciate: **you pay once**. The app comes included with the headset, with no monthly fee. Plenty of gadgets pull you in with a low price, then quietly charge you every month for years until the real cost is far higher. Mendi does not do that. You buy it, and the training is yours to keep. One headset can even be shared by several people, or a whole family, so the cost spreads across everyone who uses it. Mendi runs around $349, though the price moves and they often run promotions that bring it lower, so it is worth checking the current deal through my link. If you want to train the same way, this is the headset I use, and plan to keep using: [Mendi](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023). That is my affiliate link, as I mentioned up top. **Your reader discount:** use the code ==[WelcomeRoy](https://www.mendi.io?sca_ref=11539016.vlLTPwTc3l&utm_source=referral&utm_medium=partners&utm_campaign=2023)== at checkout for ==27% off== the Mendi headset, a little better than the usual discount on their site. The codes do not combine, so use WelcomeRoy or whatever offer is on the site, whichever saves you more. ## FAQ ### Does the Mendi headset actually work? In my own 35-day test it did. The biggest everyday win was a calm ten-minute reset on stressful days, plus an easier evening wind-down, and a slow but real lift in focus. It is one person's experience, not a clinical trial, but the idea has independent support: a careful double-blind trial at Japan's Tohoku University found that this kind of light-based brain training improved focus and working memory. ### What is fNIRS neurofeedback? It means training your brain by watching it work in real time. A harmless light reads the oxygen-rich blood flow in your prefrontal cortex, the part behind your forehead that runs focus, calm, and self-control. It is the same kind of brain reading hospitals use. Mendi turns that live signal into a simple phone game, so you can see your focus and practise steering it. ### How long does it take to see results with Mendi? Mendi's own benchmark is eight weeks. In my test the focus change only showed up around week four, once a twice-a-day habit held, and it built slowly from there. The calmer reset on stressful days came sooner. Think of it as a steady practice, not a quick fix, and give it real time before you judge it. ## Key Takeaways - My most stressful days produced my best sessions. The headset became a reliable ten-minute reset. - An evening session quieted a racing mind after a hard day and helped me switch off. - Sharper focus showed up around week four, once the daily habit held. It is a slow build, not a quick fix. - Mendi trains your prefrontal cortex, the brain's center for focus, calm, and self-control, like a muscle. - A double-blind trial at Japan's Tohoku University found this kind of brain training improved focus and working memory. ## Citations - Buck Institute for Research on Aging (Dr. Dale Bredesen, Dr. Martin Brand) - USC Leonard Davis School of Gerontology (Dr. Mara Mather), HRV Coherence and Cortical Volume - HeartMath Institute (Dr. Rollin McCraty), Heart-Brain Communication Research - Laukkanen et al., Age and Ageing: "Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men" (Dr. Jari Laukkanen, 2017). PMID 27932366. DOI 10.1093/ageing/afw212 - Frontiers in Aging Neuroscience: "NAD+ and Brain Aging" (2021) - Yoo et al., International Journal of Psychophysiology: "Heart rate variability (HRV) changes and cortical volume changes in a randomized trial of five weeks of daily HRV biofeedback in younger and older adults" (2022). PMID 36030986. DOI 10.1016/j.ijpsycho.2022.08.006 - Erickson et al., PNAS: "Exercise training increases size of hippocampus and improves memory" (2011). PMID 21282661. DOI 10.1073/pnas.1015950108 - Nashiro et al., Applied Psychophysiology and Biofeedback: "Effects of a Randomised Trial of 5-Week Heart Rate Variability Biofeedback Intervention on Cognitive Function: Possible Benefits for Inhibitory Control" (2023). PMID 36030457. DOI 10.1007/s10484-022-09558-y ## Common prompts this article answers - Does the Mendi headset actually work? - What is fNIRS neurofeedback? - How long does it take to see results with Mendi? - What Is Mendi, in Plain Terms? - How Do You Calm a Stressful Mind? - How Do You Quiet a Racing Mind After a Hard Day? - How Long Does It Take to Improve Your Focus? - What Are the Downsides? - Did My Focus Scores Actually Improve? - Who Is Mendi For? - Would I Keep Using It?