Nicotine and your sleep data: the damage your HRV will not show
Pouches and vapes are marketed as the clean option: no smoke, no tar, no smell. Whatever that is worth for your lungs, it says nothing about your night — and if you are checking whether it affects you by looking at your HRV, the research suggests you are looking at the one number that will tell you nothing.
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The experiment
Choi and colleagues took 16 healthy young non-smokers and ran a double-blind crossover: each person slept in a lab with a nicotine patch on one night and without on another, monitored by full polysomnography. Non-smokers on purpose — no habit, no withdrawal, nothing to confound the reading. Just nicotine, or not.
What got worse
On the nicotine night, participants took longer to fall asleep, spent more time awake after falling asleep, and logged more stage 1 — the lightest sleep there is. Total sleep time fell, sleep efficiency fell, and the proportion of REM fell.
The EEG analysis went further: slow-wave activity was reduced in stage 2 and REM, and alpha activity — the rhythm of a brain that is awake and idling — was increased during the first NREM-REM cycle of the night. That is not just less sleep. That is sleep that is structurally lighter while it is happening.
And the part that should change how you read your ring
Heart-rate variability showed *no difference between the two nights*.
Think about what that means in practice. Someone using a pouch in the evening, checking their morning HRV, seeing it unchanged and concluding it is fine — would be drawing a confident conclusion from a measurement that this study says does not respond. The disruption was real and measurable; it simply was not measurable there.
There was one HRV-related signal: the low-to-high frequency ratio, a rough index of sympathetic activity, correlated with how much time people spent awake after falling asleep on the nicotine night. So the autonomic story is not absent — it is just not visible in the single overnight average that a wearable reports to you.
What your ring will show instead
The things that did move are things a decent sleep tracker estimates: time to fall asleep, time awake during the night, sleep efficiency, and the balance of light against deep and REM. If nicotine is affecting your sleep, that is where to look — the shape of the night, not the heart-rate summary.
Worth knowing that a tracker's stage estimates are approximations against a lab standard, so the honest use is comparing your own nights to each other over a couple of weeks, not treating one night's REM percentage as a measurement.
The limits of this study, stated plainly
Sixteen people. Healthy young men. A patch, which delivers a steady dose across the whole night — not a pouch at 9pm or a vape before bed, which produce a completely different exposure curve. And non-smokers, which makes the causal reading clean but means it does not describe what happens in someone whose body expects nicotine and goes without.
So: this establishes that nicotine itself degrades sleep architecture in people who do not use it, and that HRV misses it. It does not quantify your pouch habit. If you want that, the only instrument that can answer is a fortnight of your own nights with and without — which is a genuinely interesting thing to run on yourself, and rather more informative than a percentage.
Frequently asked questions
Pedro Thomaz builds Vitra, a desktop app that reads Oura data against your own baseline instead of a population average. He has worn a ring daily for years and reads these same numbers every morning — which is where most of what is written here comes from. Vitra is not a medical device and nothing on this blog is medical advice.
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