What the research supports, and where it stops

Nicotine's plasma half-life averages about two hours, so a day without any leaves nothing meaningful behind. Measured instead by how it leaves in urine, the terminal half-life averages eleven hours. Even on that slower figure, roughly 1% is left at three days. Cotinine, what your liver turns nicotine into, has a half-life of about sixteen hours and reflects the past three to four days.

This is the best-grounded thing the app says, and the only milestone that needs no caveat: the molecule and the enzymes that clear it are identical whether it arrived from a cigarette or a vape.

A systematic review of 63 studies found that vaping raises heart rate by about 11 bpm and blood pressure by about 13 mmHg systolic and 8 diastolic, in the moments around it. Stopping does remove those.

But the same review found that people who vape and have never smoked showed no significant difference in resting heart rate or blood pressure from people who do neither. If there is no raised baseline, there is nothing to settle back down from, so the honest claim is about the spikes you stop having, not about a recovery. The authors say plainly that the evidence here is still limited.

A review of 120 studies lists irritability, anxiety, low mood, trouble concentrating, impatience, broken sleep and restlessness as genuine signs of stopping tobacco, peaking in the first week and lasting two to four weeks. The National Cancer Institute puts the worst of it in the first three days. Nicotine's effect on sleep has its own literature (longer to drop off, more broken nights, less slow-wave sleep), though after stopping, those effects are often tangled up with withdrawal.

Two to four weeks, not one. The app used to say a week about sleep, which is the kind of small error that leaves someone on day eighteen thinking something is wrong with them.

Two brain-imaging studies followed nicotinic receptor availability after people stopped smoking. One (n=16) found it back at non-smoker levels by 21 days. The other (19 smokers against 20 non-smokers) found it significantly higher at one week, and no different from non-smokers at four weeks.

Thirty-five people between them, and they disagree by a factor of three on when. Both measured people who stopped outright: nobody has scanned anyone halfway down a taper, so what receptors do while you are cutting down is simply unknown. We say "somewhere between three weeks and three months" because that is the width of what is actually known.

Eighty-six smokers were paid to go without for 7, 14 or 35 days, with daily verification. Craving triggered by cues increased with time on some measures and decreased on none, while background craving and withdrawal subsided. Among people quitting smoking without help, most of those who go back do so in the first eight days.

That is the opposite of what quit apps usually promise, and it is more useful. A cue that knocks you sideways in week three is the normal shape of this, not a sign about you.

The app once told you your airways were relaxing at 72 hours, your circulation improving at two weeks and your lung function measurably recovering at one month. All three were borrowed from the NHS's stop-smoking timeline, where they are driven by the end of combustion, and the last one is in the wrong place even there, since that page puts lung function at three to nine months.

The nearest respiratory research we could find goes the other way entirely: it follows people switching from cigarettes to e-cigarettes, and says nothing about the lungs of someone who stops vaping. Where a claim can't be supported, the fix is to cut it rather than soften it.

Thirty-one undergraduates were prompted seven times a day for a week and randomly asked either to play Tetris for three minutes or just to report. Playing produced a mean drop of 13.9 percentage points in craving strength on a 0–100 scale, consistently across the week and across cravings for nicotine, alcohol, caffeine, food and activities. A companion lab study explains why: holding a visual task in mind crowds out the imagery a craving runs on.

Thirty-one students is a light finding and we won't dress it up. It is still the best-evidenced thing in the app's craving screen, and it is why Clear the air is clouds to push away rather than anything vape-shaped: showing someone the thing they crave is how researchers deliberately bring a craving on.

Ninety-six smokers, twelve hours without a cigarette, were randomly given ten minutes of paced breathing or a video. Every craving measure was lower in the breathing group immediately afterwards. By 24 hours the difference had gone, because people did not keep doing it on their own. Putting the exercise one tap away at the moment you want it is a reasonable answer to that, and we'd rather say so than imply the effect lasts.

The pattern we use (in for 4, hold 4, out for 6) is a slow one, under ten breaths a minute, which is where the physiology has been measured. No trial has compared one ratio against another for craving, so ours is defensible as a slow pattern, not as the best one. Across breathing research generally the effect on stress is real and small, and those authors warn about "a miscalibration between hype and evidence", which is roughly the house position.

A hundred and twenty-three student smokers were randomly given brief urge-surfing instructions or none, then exposed to cues. Their urges did not differ. What differed was what they did over the next seven days: the instructed group smoked significantly less.

In the authors' words, the technique may not reduce urges so much as change the response to them. That is a smaller promise than most apps make, and it is the one the research actually supports.

A hundred and thirty-three people recorded their first cigarette after quitting on a handheld computer within minutes of it happening, then were followed for three months. How they felt about it (self-efficacy, what they blamed, how bad it felt) generally did not predict what happened next. Neither did how much they had, nor how good it was.

Two things did. People who felt like giving up afterwards got to a second one faster. People who tried some small restorative thing were less likely to have another the same day. That single result is the whole argument for how this app talks to you: a product that provokes the giving-up thought is working against the person using it. And getting through one is a real event: in 2,713 recorded moments of temptation, 46% ended in smoking, so roughly half are survived.

Across 21,539 smoking and 26,930 non-smoking moments from 406 people, smoking was under considerable stimulus control: mood, place, activity, who you are with, time of day. But those models were fitted one person at a time, which is the whole point. Mood and setting mattered most; food and alcohol mattered least, which is the opposite end of the list most quit guides lead with.

Laboratory cue responses did not predict real-world ones at all (mean r = 0.03), and stimulus control is weaker at higher intake, so the heaviest users are the least predictable. That is why the app asks you to tag your own moments rather than handing you someone else's.

A meta-analysis of 138 studies and 19,951 people found that prompting someone to monitor their progress increased how much they monitored, and increased how often they reached the goal (d+ = 0.40, CI 0.32 to 0.48). Monitoring frequency carried the effect, and recording progress physically made it larger.

That is a finding about goals in general, not about nicotine in particular. It is better evidenced than the taper itself, and we would rather say it that way round than imply it was measured in people quitting vapes.

"Cravings pass in three to five minutes" is on quit sites everywhere. We tried to trace it and found websites quoting websites, never a study. The one paper that did measure how long episodes of temptation last reports that their average duration predicted outcomes, but the number itself isn't in the abstract and we could not get the full text. The National Cancer Institute declines to give a figure at all, saying only that the urge will come and go.

So the app's craving screen tells you what to do with the minutes and no longer tells you how many there will be. If you have ever had one last half an hour, you were not doing it wrong.

It is the most comforting sentence available and we cut it. No study has looked at whether resisting one urge changes the next. What exists points the other way for cue-driven craving, and the one trial of a coping technique found urges unchanged.

What does fall over a quit attempt is how often temptations arrive and how strong the background pull is, in 214 people tracked daily. That is a true and quieter thing to say, so it is what the app says.

There is a large literature on paying people to quit, and it is broadly positive. There is nothing we could find on showing someone the money they didn't spend, which is a different intervention entirely. This is the one entry on the page with nothing to cite, which is the point of it.

The money screens do arithmetic on a price you typed in. That is all they claim to be, and we won't dress it up as a reason the plan works.

Slow breathing has measured physiological effects below about ten breaths a minute. No trial has compared inhale-to-exhale ratios against each other for craving or for stress, so nobody can tell you that 4-4-6 beats 4-7-8 or box breathing. Ours is slow, which is the part that has been studied.