Show HN: I'm a doctor and made a responsive breathing app for stress and anxiety (lungy.app)

666 points by lukko ↗ HN
Hey HN! Some more info: I’m an NHS doctor and the founder of Pi-A (https://www.pi-a.io) which developed Lungy (https://www.lungy.app). Lungy is an app (iOS only for now) that responds to breathing in real-time and was designed to make breathing exercises more engaging and beneficial to do. It hopefully has many aspects of interest to the HN community – real-time fluid, cloth and soft body sims running on the phone’s GPU.

My background is as a junior surgical trainee and I started building Lungy in 2020 during the first COVID lockdown in London. During COVID, there were huge numbers of patients coming off ventilators and they are often given breathing exercises on a worksheet and disposable plastic devices called incentive spirometers to encourage deep breathing. This is intended to prevent chest infections and strengthen breathing muscles that have weakened. I noticed often the incentive spirometer would sit by the bedside, whilst the patient would be on their phone – this was the spark that lead to Lungy!

The visuals are mostly built using Metal, with one or two using SpriteKit. There are 20 to choose from, including boids, cloth sims, fluid sims, a hacky DLA implementation, rigid body + soft body sims. The audio uses AudioKit with a polyphonic synth and a sequencer plays generated notes from a chosen scale (you can mess around with the sequencer and synth in Settings/Create Music).

There are obviously lots of breathing and meditation apps out there, I wanted Lungy to be different - it's about tuning into your surroundings and noticing the world around you, so all the visuals are nature-inspired or have some reference to the physical world. I didn’t like other apps required large downloads and/or a wifi connection, so Lungy’s download size is very small (<50MB), with no geometry, video or audio files.

Lungy is initially a wellness app, but I’d like to develop a medical device version for patients with breathing problems such as asthma, chronic obstructive pulmonary disease (COPD) & long COVID. Thanks for reading - would love to hear feedback!

222 comments

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Looks extremely cool, but I wish this was a web app. I can't use it because I don't have an iOS device and I also think it would be useful on desktop, to take a break, as an alternative to checking HN, twitter ...
Thanks! Yep, I would love for it to also be a web app one day, I think definitely would be possible now with WebGPU. Will hopefully be able to release an Android version this year..
awesome. Looking forward to trying this on Android!
This looks really nice. I'd love to know more about the business model. Is it completely self-funded? Does it make any revenue? Are you using it as a mechanism to help your practice? Thanks!
Thank you! So for now it's freemium, as a wellness app - so monthly, yearly or lifetime subscription to unlock all visuals, features and exercises. It may be at some point it can be provided via NHS trusts / health insurance companies.

For the first year or so it was self-developed and self-funded, and then in 2021 I won a couple of grants to develop the prototype for release. I don't suggest it directly to patients as there would be a conflict of interest, but I'm hoping it could be useful in both respiratory disease and stress/anxiety.

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Looks cool. I would try it. I'm on Android. This could be a PWA for both web and Android targets. Not sure about iOS yet, do they still not support PWAs?
Or flutter to target all 3 :)
Highly encourage exploring Flutter as well, at least for new platforms. Lottie animations would pair nicely, as would any future goal of expanding to web or desktop.
Flutter is just awesome. Can't recommend it enough.

Never had an easier time porting UI to so many, different platforms.

Flutter alone saved a year of work.

Thanks! Flutter does sound good, I've just started looking into it. Am I right in thinking we would rebuild the UIKit components / views in Flutter and then would be able to use the same UI across platforms (iOS, Android + Web)? And it would still be possible to include the native Apple APIs?
Yes to how you imagine the UI layer, and yes you can definitely target both iOS and Android native APIs with Flutter.
PWA would cover KaiOS as well.
I’m probably not the target market, but why do you need an app to conduct a breathing exercise?

I’m any case, the app looks polished.

Tutorial, catalog, ritual-starter, historical log, etc. To your point, it's not necessarily for everyone.
Good idea but I don't have an Apple device to try it.

If you get some traction you might consider porting the app to run on smart watches. Current Garmin wearable devices are apparently able to detect individual breaths using the wrist optical heart rate sensor based on slight difference in heartbeat timing. They have a breathwork app built in but functionality is very limited.

side note -- is it just me, or have Vimeo videos always been horrible as embeds? They take longer to load than YouTube, they take too long to fast-forward (click in the middle and wait 5 seconds before you see the video at that time location).

And on this embeded video I couldn't even change the volume!

It's frustrating me to the point that I just opted not to watch the video on this website :(

I don't want to say "it's just you" but the load circle was less than 1 second, and skipping ahead was instantaneous for me.

Maybe it's CDN location serving up the videos? I'm near Toronto. Also I checked your webpage and perhaps, by being in the business of video streaming, you're more attuned to these things than the average person? (P.S. your website is so elegant!)

I’ve been on the lookout for a better way to do embeddable videos. The YouTube one is fine, but for a landing page, it’s not great that YT (of course) tries to get you to watch recommended videos right afterward.

I was actually going to say, Wistia has a nice player but it’s expensive - and then I just checked their pricing and they actually have lowered prices quite a bit! There’s even a generous free tier now.

I’ve also been curious about how hard it’d be to self-host an embedded video. Naively it seems like the hardest part would be encoding it into a bunch of sizes and chunks… and then keeping an eye on bandwidth. I found a good blog on it a while ago and can’t find it now.

Very nicely designed.

Is there a paper showing the accuracy of measuring breath volume and frequency using a phone microphone as compared to other known methods (i.e, medical sensors, but also more consumer-focused devices such as chest straps)? The frequency seems like an easy problem to solve, volume much less so.

Hmm, I'll have a look - that would be a really good figure. You can estimate the air velocity with the mic (then derive the flow rate and volume), but I'm not sure how closely it matches spirometry (lung function tests)
Very cool. A white paper on your site would help convince those who may have questions as to the validity/accuracy of the measurements themselves.
My brother made something similar as an art project: it's a circuit board with 2 LED digits. The numbers increase quickly on the inhale and slowly on the exhale so that it's in sync with 10 breaths per minute. It lures you into following it's cadence with your own breathing and you eventually get lightheaded because you're fucking with your blood gases.
Yep - that is one of the reasons I wanted to use the mic input, so if someone was hyperventilating it would be possible to tell them to slow down and breathe less deeply.
" 10 breaths per second."

Sure hope you meant per minute!

WOW! This is really ground-breaking. Will the android version be supported as well?
Thank you! Working on it, hopefully at some point this year..
Filament & Oboe should match iOS performance in both realms: real time physically based sprite render, and polyphonic synth. Good Stuff, ideal for ai gurus teaching "pranayama sciences" ;)

Brief structured respiration practices enhance mood and reduce physiological arousal

https://www.cell.com/cell-reports-medicine/fulltext/S2666-37...

oh amazing, I was looking for equivalent frameworks - thank you!
This is cool - have you ever thought about integrating it with some kind of band or sensor that tracks breathing rate?

Lung diseases aside, I think many people would be interested in an app that lets them know when their breathing becomes shallow or non-tidal, and helps them refocus and get back to baseline.

It's awesome that the app is free and will allow helping the most people.
I like this idea and the design – the gamification is a good approach in my view.

A question for you: I have a relative who has been recovering from a pneumonectomy – is this a use case that you currently support or plan to support in the future (i.e. are the breathing exercises on the app similar to the ones prescribed for these patients)?

Yep, it would definitely be a use case - so post-operative chest or abdominal surgery patients are often given breathing exercises. It's not yet a medical device, so can only be used in stress and anxiety ('wellness'). The basic functionality would be similar - breathing exercises, responsive visuals, encouragement, but hopefully we can add more specific measurements of lung function in the medical device version (track improvement / deterioration)
Rad – that would be really interesting to have specific measurements and use cases associated with surgical recover. Haven't tried the app out yet – may have some more questions once I do. Thanks!
Reminded me of a startup that makes "hugging-pillows" that expand/contract to regulate breathing during sleep as in synchronous breathing with a partner.

EDIT: found it: https://somnox.com/

They are quite expensive.

(Not affiliated)

Looks very cool. Did you do the design yourself or use someone else?
Thank you! Yep, I designed the visuals and the screens were a joint effort with a UI designer.
A few years ago a friend told me about something called eye movement desensitization something (EMDR). I wasn't buying it but I built a prototype anyways, and was really impressed with how effective it was. The code is super crappy, but the experience is quite good imo. Here's a link:

https://bradbarb.in/emdr/demo/

Bit of a tangent. I'm irked by comments such as this, that are mildly related but add not much value to the discussion besides a shameless plug for their own products.

Fwiw

I agree. It's felt like a lot of online forums are starting to become Quora where it's all self-promotion thinly veiled as adding to the conversation. It reminds me of PG's The Submarine blog post (http://www.paulgraham.com/submarine.html)
As the OP is about an app for stress and anxiety, promoting similar apps doesn't seem all that unreasonable.
I feel you. But it's not a product. Not anything I'm doing anything with. Just thought it might be an interesting thing for the OP to integrate into his app.
I disagree and it seemed like a genuine comment to me as breathing exercises seem similar to eye exercises to me.

GP’s site is just a non-commercialized prototype so seems more like showing vis level of interest vs self promotion.

What was your experience? I've only used EMDR in the background of 1 on 1 therapy so I'm wondering what you get out of it when used in isolation?
I find it relaxing. Can't really say much more than that because my experience is limited to that link I posted. How about you?
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Are there instructions on how to use this somewhere? Should I be following the circles or looking dead center and allowing the circles to go into my periphery?

Thanks!

> Makes breathing beautiful.

I had to pause a bit for this while reading the page. This was a brand new phrase for me, never expected to see it in a mobile app.

"free with in-app purchases"

What a boring future, "pay $9.99 to unlock this secret tip to survive in case you have trouble breathing!"

health is not a thing that should available with a pay-wall, we must advocate for a better world

OP was under no obligation to build it in the first place. Arguably the alternative to a $10 app is no app at all.
Few feedbacks: - It think description in the store is too exhaustive. Be more to the point.

- I like the concept as I was using mindfulness app mostly for the breathing exercises but ended up downloading the video and playing it to myself. I like that the whole app is just around this.

- I personally would enjoy a mood tracker and a daily notification or quiet time moment reminder to increase adherence.

- on top of this some motivational aspects and smileys can help :)

Good job by the way.

PS: I manage a patient facing MS app will many trackers:).

This sounds really cool. I struggle from anxiety and the occasional panic attack. The only thing I've found so far that helps is the Wim Hof breathing exercise. Three rounds of that gets me grounded again no matter how bad my anxiety is. I do usually breathe off tempo from the guided exercise, so I really like the idea of an app that adjusts to you.
I can't test your app, since I don't have an iPhone, but I'm hoping you could answer a vaguely related question for me.

One of my COVID readings was Breath: The New Science of a Lost Art, by James Nestor. Its author says, "humans have lost the ability to breathe correctly". Like your app, it proposes a lot of breathing exercises. It explains their benefits in terms of increasing CO2 tolerance, and believes that we've all got too much O2 in our systems.

That smells like horse puckey to me, but I've been unable to find an informed review either way. I'm sure that slow, deep breathing as a focus for meditation is a very good thing, and I'm sure that your particular app is well founded. But I'm curious to know if you've read that particular book, and what your opinions are.

Thanks!

One great thing with increasing co2 resistance is I can hold my breath for ~5 minutes and thus freedive / snorkel deep and stay long under water. But other than that I'm not sure, also curious about if it has any more health related benefits.

For practicing breath holding, "co2 tables" is the exercise to go for, btw. I find it very relaxing in a sort of meditative "ignore the burning pain" sense, but not sure I'd recommend it vs the app in the OP hehe.

There is a feedback loop that characterizes the stress/anxiety response, where people breathe faster, which in turn increases the stress response, causing even faster breathing. People with chronic anxiety also develop decreased CO2 tolerance over time[1] from this rapid breathing, perpetuating the chronic rapid breath.

Breath exercises that increase CO2 tolerance like Buteyko breathing allow one to interrupt this process. It's not clear to me exactly what the increased CO2 is doing, if anything, but it's clear that this works to escape this chronic stress state, which is really unhealthy.

I think the Radiolab breath episode discusses this well: https://radiolab.org/episodes/breath

[1] https://pubmed.ncbi.nlm.nih.gov/11015814/

I recently came across this by accident and your explanation jives.

I noticed I would get fairly fatigued, and have to take a nap around 11am every morning, and eventually found that it was basically every 4-5 hours, even mid-day too. I would take a 10-20m power nap and usually wake up feeling really good, I would even hit REM in that time.

Then a few months ago, I noticed when I was having this feeling I was usually ruminating about something, and it was something like grappling or repressed anger, AND what this did was cause very shallow breathing and "breath holding" patterns. And I've been doing a lot of work around Gabor Mate, MD's work lately and processing trauma responses so I was able to identify this and feel the feelings in a more present way, and in doing so, start very intentional deep, slow breath and exhales.

Compared to my shallow breathing and holding, my breaths became like 3-4x longer. And... to my surprise, the fatigue would pass in about 5minutes or so and I would not need a nap, and get my brain back to an "alert" state, as opposed to that "foggy" state.

I have been doing this for months now, and it keeps working. And now, this was really blurry because sometimes I would be genuinely tired from sleep debt from pulling a late night, and it was a similar feeling. So when I get a solid nights sleep for multiple nights in a row, then the breathing works to keep me alert, and helps me get more in touch with my emotions and subconscious thoughts rise up and become concious. I can detect the shallow breathing/breath holding fairly well now, but not always, and it is still a work in progress to make these breaths the default. The breathing does help me move through life much better now, and I walk slower, and not so rushed, and am more at peace with doing things in the present.

This actually wouldn't really be possible though if it weren't for a discovery that I breathed through my mouth my whole life (40 years) recently too. I learned about the "nasal cycle" and in combination with a deviated septum I have, my nose would plug up every now and then with no rhyme or reason, I thought it was diet for a long time but eventually learned about the "nasal cycle" where the turbinates in our noses swap the swelling to change the airflow every 4-6 hours or so. And when it swapped to my non-blocked septum side, my airflow would stop and I would be forced to breathe through my mouth. What this meant is that I could never develop a habit of nasal breathing my entire life. I started using Afrin about 5 months ago, and then stopped because it says not to use it continuously and you get a rebound when you stop using it. But then I found a Ear Nose Throat doctor/surgeon and presented my hypothesis to him and he confirmed that the nasal cycle + deviated septum hypothesis was correct! And he suggested I use Afrin plus a nasal steroid (Sensimist) together and that will reduce the rebound effect and that enabled me to use Afrin long term to stop the natural swelling of the turbinates in my nose. And, so I've been using Afrin for 3 months now and can breath so good through my nose now, and it is so sweet, and so precious, I can't imagine going back to mouth breathing ever again. I do have increased sensitivity to cold with the Afrin and my nose drips like a faucet. Or maybe that was because I never breathed through my nose in the cold to begin with? Regardless, I need to bring tissues with me in cold weather wherever I go.

And that leads to the fact that now when I noticed the breathing pausing, I can take big deep breaths through my nose and it feels so good, and calming, I can break out of the trauma/anxiety cycle and self-regulate with breathing.

I think the breathing cycle issue is mostly a trauma response from a young age and then it turns into a learned habit. This is the result of a caretaker not being there for me/us to help us self-regulate at a young age. The Wisdom of Trauma film and In the Realm of th...

Thanks for writing this all out—I too have a deviated septum and can relate to a lot of what you wrote. Have you considered surgery for your nose?
Yes, I forgot to mention but I have surgery coming up in February so hopefully I want need my Afrin dependency anymore! I wasn't sure about surgery at first, and was just super duper happy I could breath through my nose, after 40 years of not even knowing that it wasn't normal to breath only through my mouth. But after a few months of this precious nose breathing, and my mouth not drying out at night anymore which caused me to want to drink water at night, and would contribute to waking up to pee, getting shitty sleep, and putting me in chronic stress from sleep deprivation, I now am ready to take the next step and get surgery to fix the deviated septum and have my turbinates function as they were intended to again!
If you have poor nasal breathing you should consider EASE https://drkaseyli.org/ease . People in your situation often have narrow jaws which can result in a narrow nasal aperture and poor airflow
I'd never come across this, but it looks promising. I broke my jaw in the past, so I imagine I'm even more at risk of having jaw related breathing issues. Thanks for sharing!
Good luck with the surgery! I'm looking at doing it next year myself. Anecdotally, everyone who I ran into locally who'd had his said the same thing: they wish they'd done it sooner—ergo, it sounds like a winner. Again, thanks for sharing your wisdom in your original post. All the best!
WOW this post resonates with me on so many levels. Thank you so much for writing it out!

-I have the exact same issue, I feel overwhelming fatigue that lifts with a 10 minute nap, and need to do it many times per day. I work from home, and can't really work in person because without a nap I just crash, despite getting a good nights sleep -My girlfriend pointed out that I normally breath unusually fast and shallow, about twice as fast as her -I've had some very traumatic experiences in the last few years that I still haven't dealt with fully. Around the time of these experiences I couldn't sleep well because I had to constantly get up to urinate, and also at the same time felt an "air hunger" where I felt no amount of breathing was enough

Could you recommend something specific to start working on with these things? I actually just started reading the Mate book "The Myth of Normal" but haven't gotten very far in it yet.

It seems like there are quite a few people here discovering these things, I wish we could form a discussion group or something.

> constantly get up to urinate

I hope you've been checked for diabetes?

The problem went away immediately when the massively stressful event was passed.
Well, first thing is, can you breath through your nose? Do you have that habit down? Fixing this is really important, for me at least. If a person can't breath through their nose, I suggest trying Afrin. This was such a huge lightbulb moment for me, and was my "AHA" moment. I really didn't know that the normal human condition is to nasal breathe. My mom has the same condition and I was raised by her so I didn't realize it and she didn't either to even notice it in me. It works instantly, within 10 minutes, and my world was opened up! And it still took me months to form the habit of nasal breathing, because I could never trust it enough when it worked (due to the nasal cycle). I definitely do Afrin just before bedtime too, every 12 hours or so. And I am getting surgery for the deviated septum too in February.

Second thing, do you have chronic pain? That will keep the body in a stress response. Chronic pain is actually easier to get rid of than I thought, and I tried a lot of things for 20 years. The new research at University of Colorado Boulder, using functional MRI scans in 2020 proves that much chronic pain can be eliminated in a short period with a very specific technique called Pain Reprocessing Therapy (PRT), which is a compassion-based therapy. This is a really, really hard thing to believe, and one doesn't have to believe it fully, they just have to believe it enough to be curious and learn more. And if one is curious, I recommend listening to a 15 episode mini-series podcast called Tell Me About Your Pain by Alon Gordon (Pain Pyschologist) and Alon Ziv (Neuroscientist), then after that listen to the audio book (not ebook) by the same people called "The Way Out" (2022). Then there are 6 specific meditations by Alan Gordon on an app called Curable that I used to eliminate my chronic neck and back pain, I can dig up the link to them if you like. This same technique is what I use to react to my shallow breathing and fatigue with deeper breathing. This got me sleeping through the night.

Third, the trauma therapy (it isn't if we have trauma, it is how much), I recommend starting with the film The Wisdom of Trauma. And if that is interesting then reading In the Realm of Hungry Ghosts. Myth of Normal seems like a great book too, I haven't read it yet though but it is on my list. I did start reading Gabor's AD(H)D book Scattered Minds a while back, way before this breathing breakthrough surfaced and need to finish it, but to sum up one thing I learned I have ADD-Like symptoms and this whole shallow breathing thing I have noticed is a large part of it. Once I start conscious breathing, by ADD-like stuff reduces. I've been more motivated to actually exercise and not fall asleep doing it, and I have been working on cold-exposure therapy (What Doesn't Kill Us by Mark Carney, investigative journalist who tried to debunk Wim Hoff, ended up drinking the Koolaid, and explains why). The cold-exposure increases the chemical called norepinephrine, which is one of the chemicals that Adderall increases (along with Dopamine). There is a quote from the film "My Octopus Teacher" (fantastic film) where he says "the cold really upgrades the brain" and references him diving into the ocean without a wetsuit almost every day for a year making friends with an octopus. I really like that quote. The cold does help me think when I do it, and I am still easing into it, and getting my brain back.

All in all, I feel at a really new phase of my life, and that includes this thing called "Hope". I no longer think my fatigue is caused by my diet, and in fact I know it isn't.

I'm happy to chat about this with you or anyone else. I'm also open to saying "hi" on a real-time communication (RTC) chat here https://cal.com/ElijahLynn.

I’m constantly blown away by the nuggets of wisdom I find on this website! Thanks for such a breath of knowledge, no pun intended. Going down a rabbit hole of chronic pain. Thank you
> If a person can't breath through their nose, I suggest trying Afrin.

Be careful of the "rebound" effect with nasal sprays. Years ago I was "hooked" on Afrin. Not in a getting high sense but in the sense that I started to constantly need it in order to breath out of my nose, even after my cold went away. It was a terrible feeling and took weeks to wean off.

With a bad cold and miserable congestion, nasal spray like Afrin is like a miracle. I still use it in those instances but only for 2-3 days max and very sparingly.

If you really can't breath out of your nose well see a doctor.

https://www.mayoclinic.org/diseases-conditions/allergies/exp...

https://www.goodrx.com/conditions/nasal-congestion/rebound-c...

This is very true! And my doctor/surgeon said that if you use a steroid like Sensimist with the Afrin then the rebound effect isn't as severe, which appears to be someone true so far. I do a spray of Afrin, then 10 minutes later do 2 sprays of sensimist. It isn't ideal and I am switching to surgery option now that I have tested it out for a few months now and would like to make it permanent!
i see you follow gabor mate and i see lot of talk about trauma and understand people's need for processing it and so on. ptsd is real, not denying that. having said that, in the past years i have actually been moving in the other direction, that sometimes trauma narratives tend to keep people stuck in the past. it solidifies certain types of trauma, makes it part of a person's identity and hampers recovery for some. one trouble is trauma is associated with lot of meaning and we tend to stick to things that are meaningful. i understand that too much thinking in this direction isnt correct and the truth lies somewhere in between. just saw that you have been aligning too much towards one direction so couldnt help but mirror that.
I worked with a trauma therapist and this was exactly what we worked on. The way out of trauma is to find out / realize that you’ve worked your way out of trauma. That the danger zone is gone.
Nocturia + Sleep issues could mean Sleep Apnea

I don’t snore, I am not overweight.

And I had some ADHD like symptoms.

My doctor didn’t think that it would be useful to test but I insisted, lack of sleep was making me desperate. I took at least three naps a day just to be able to function.

The results were surprising even to me, AHI of 23.

CPAP treatment has been life changing.

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This resonates a lot for me. My nose has never worked right. Like, for instance when I get nosebleeds it always come out of the same nostril 100%.
Thanks a lot for the detailed writup, I'm currently investigating similar stuff but didn't really know whereto look, this will help me a lot.
i want to ask chatGPT to summarise this for me and repost but i'm not sure if that's welcome here.
As a permanent snorer and nose cold sufferer several tips in that book worked wonders for me. I already had a good set of lungs and low breathing rhythm thanks to swimming, but a few weeks of sleeping with my mouth taped shut and attention to my jaw posture solved quite some issues. (N=1 YMMV etc)
+1 For tapping the mouth shut. I used to snore and wake up tired now that I use 3M-1530-2 tape I wake up refreshed. So N is now equal to 2 !
+2 for taping mouth shut.

I read the book a week ago, said, why not. Instant improvement. Before, I'd have to wake up to go to the bathroom every night for the past 10 years, and when I woke up I'd have this eye pain every day leading to these giant eye bags. On top of those, if I didn't get that last sleep cycle in, I'd have to take a nap to get rid of this weird headache which made the time in the morning before nap seem pointless. In the book he mentioned how face skin can improve, and less bathroom in the middle of the night because apparently the body releases something to tell the body to hold water because we're sleeping. Mouth breating at night didn't cause this to happen.

I did the mouth tape and instantly, first night and every night in the past week, eye pain is gone, I don't have get up to use the bathroom, and the amount of consistent energy is absurd compared to before.

Seriously, I want to shout it out to everyone to tape their mouths at night.

+4 with my wife and I. I have sleep apnea from a deviated septum, she has various breathing issues from EDS. We both sleep better now.
I haven't read the book, but just hearing the idea to tape my mouth shut induces some anxiety. Isn't it dangerous that you don't get enough air?
I can see how it can cause some anxiety. I suppose I was lucky that it didn't for me. The first two nights I work up in the middle a couple times, decently alert, and could tell my body was trying to say something might be wrong. I was able to fall asleep quickly though, which also was something I wasn't able to do before.

If you might have that anxiety, I'd say try putting tape on your mouth during the day at times to get used to it, and you might find you'll forget about it and that can ease the worry. It might be difficult, but we all can breathe only through our noses, even if that requires some practice and reassurance.

It did cause some anxiety for me. But I use a soft tape that easily comes loose with just the back of my hand or a big jaw movement.

I especially enjoy how the nasal cycle with nose breathing just seems to physically “halve” colds. Even with a cold with nose breathing one nostril just opens up at night in order to let me breathe.

You can actually cut a little slit in the mouth tape, so that you won't panic. Breathing a straw sized amount of air through the mouth if you need to, will prevent suffocation anxiety, but also limit your mouth breathing enough that your nose does most of the work.

Watch this guys two videos on a DIY CPAP. https://www.youtube.com/watch?v=g8JzXEoT9LI

I think I would staying awake at least the first nights just by the thought that I have my mouth shut, and "what if I cannot breath and I die", or "this is so uncomfortable" etc etc. How did you manage that?
Yeah, the first two nights I woke up decently alert a couple times which I took to be my body telling me that something might be wrong and I should check it out.

I never felt a sense of uncomfortableness, it felt almost comfortable for me as if the tape was making me feel more secure, maybe? Similarly I didn't have the worry about not being able to breathe and not know about it. In both those cases, don't feel weird about wearing some around when waking and you can get used to it.

The other mindset to have is remember that our bodies are really incredible at things after millions of years of evolution. Nose breathing especially is something we're able to do. That acknowledgement and trust can go a long way mentally.

What kind of tape do you use? I've just started trying this and best I have found so far in my local grocery store is Nexcare Absolute Waterproof tape. It stays on all night, but I wondered if there was something a bit easier to remove.
I just used a regular soft bandage tape (‘leukosilk’). In the beginning I sometimes ripped them off in the night, so I’d go with something soft.
My understanding from the book was that CO2 is an essential part of the mechanism that transfers oxygen to your muscles. If you breathe too much you have too little CO2, your muscles can't get enough oxygen and they don't work efficiently. I've no idea if this is true, but since I read the book I breathe less when exercising and it seems to help. Edited to add: I'd forgotten, when I first started breathing less during exercise it made a huge difference, like coming down from altitude. I recommend it.
Exactly what I was looking for!

A quick suggestion, I’d love to see you add the “cyclic sighing” pattern from [1] as it’s recently gotten some amount of attention for it’s effectiveness, and is potentially less common than the others.

[1]: https://www.cell.com/cell-reports-medicine/fulltext/S2666-37...

This would be great to include! I have been getting a few requests since the article was published...
I always love apps like this. Would love to try it out when it's available on other platforms someday.
The animations are really slick for an indie app! Well done!
Thanks! AE + Lottie