What Is UARS?
You're exhausted. You've been to the doctor. You've had the bloodwork. Maybe you've even had a sleep study.
And everything came back "normal."
I know that feeling, because I lived it. You don't feel normal. You feel like you're wading through concrete. You wake up with a racing heart, or a dry mouth, or just a profound sense of dread.
One of the things worth learning about — and asking a sleep specialist about — is upper airway resistance syndrome (UARS).
What UARS actually is
UARS was first described by Guilleminault and colleagues in 1993: patients whose sleep studies didn't show apnoea, but who were still struggling to breathe against a narrowed airway at night, waking briefly over and over, and exhausted during the day (Guilleminault et al., 1993).
Unlike obstructive sleep apnoea (OSA), where the airway repeatedly collapses far enough that breathing pauses or clearly reduces, UARS is more subtle. The way I picture it: imagine breathing through a narrow straw all night. You're usually still getting enough oxygen — in UARS, oxygen levels typically don't drop the way they do in apnoea (Guilleminault et al., 1993; StatPearls) — but the effort required to pull air through that narrowed airway keeps disturbing your sleep.
That extra effort is what the literature calls flow limitation: air still moves, but not freely, and the breathing gets harder without ever stopping (Bao & Guilleminault, 2004).
An honest caveat before we go further
Here's something a lot of pages about UARS won't tell you plainly: UARS is not a separate diagnosis in the current international classification of sleep disorders. The ICSD-3 folded it into the obstructive sleep apnoea spectrum, on the grounds that the underlying mechanism is the same (American Academy of Sleep Medicine, ICSD-3, 2014). There's also no single agreed set of diagnostic criteria, and researchers still debate whether UARS is a distinct condition, an early stage of OSA, or simply the mild end of the same spectrum (de Godoy et al., 2015).
Some studies have found that a portion of people first described as having UARS later met criteria for OSA — but in the follow-up research I've read, that progression was linked to weight gain over the years, so whether UARS itself "turns into" OSA is genuinely unsettled (de Godoy et al., 2015).
None of that makes the experience less real. It just means the label sits in contested territory, and I think you deserve to know that before you go into an appointment armed with it.
Why standard tests can miss it
Standard sleep study reports lean heavily on two things:
- Apnoeas and hypopnoeas: pauses or clear reductions in breathing, summed up in the AHI (apnoea–hypopnoea index).
- Desaturations: drops in blood oxygen levels.
In UARS, you may have neither in meaningful numbers. What shows up instead — if it's scored at all — are RERAs (respiratory effort related arousals). The AASM scoring manual defines a RERA as a sequence of breaths lasting at least ten seconds with increasing respiratory effort, or flattening of the airflow signal, that ends in an arousal from sleep without meeting the criteria for an apnoea or hypopnoea (AASM Scoring Manual).
In plain terms: your brain registers the struggle to breathe and pulls you up out of deeper sleep just enough to open the airway. You might not remember waking at all. My interpretation of my own nights — the racing heart, the dread on waking — is that I was spending them in a low-grade state of alarm, and that fits how I've seen the mechanism described, though I want to be clear that's me joining the dots on my own experience.
The catch is that not every lab scores RERAs, and many home sleep tests aren't designed to detect them. Which is how you can genuinely have disturbed breathing at night and still be handed a "normal" result.
Symptoms described in the research
The picture reported in the UARS literature looks different from the classic sleep apnoea stereotype. Alongside fatigue, unrefreshing sleep, and insomnia, the research describes things like cold hands and feet, low blood pressure, light-headedness on standing, and gut symptoms in a notable share of patients (Bao & Guilleminault, 2004; StatPearls; de Godoy et al., 2015). Sleep-related teeth grinding and waking at night to pee also appear among the associated complaints.
From my own experience, the ones that rang truest were:
- Chronic fatigue, even after eight or more hours of "sleep"
- Feeling wired but tired, with anxiety humming underneath
- Dizziness when I stood up too fast
- Waking in the night more often than made any sense
On demographics: you'll often read that UARS mostly affects "thin young women." The research is a bit more careful than that. Compared with typical OSA patients, people described as having UARS do tend to be younger, leaner, and more often female — but published case series average around 50% women, so this is absolutely not a condition that only affects one body type or sex (StatPearls; de Godoy et al., 2015).
And to be equally clear the other way: this symptom list overlaps with a lot of other conditions. Ticking boxes on it does not mean you have UARS. It means you have questions worth bringing to a doctor.
Getting properly assessed
If any of this sounds like your nights, the useful move is a conversation with a sleep specialist — ideally one who is willing to talk about RERAs and flow limitation, not just AHI. Questions I'd now know to ask going in:
- Will this study score RERAs, and will the report include an RDI (respiratory disturbance index, which counts RERAs) rather than only an AHI?
- Is an in-lab study an option if a home test comes back normal but symptoms persist?
I'm not going to tell you which treatment works, because that's a conversation for you and a specialist, and the evidence base for UARS treatment is still thin — the main review on the subject says as much (de Godoy et al., 2015).
What I will tell you is this: "your test was normal" and "your sleep is fine" are not the same sentence. It took me too long to learn that.
Sources and review
I reviewed and updated this post on 19 August 2026. The general claims about UARS — its original description, mechanism, symptoms reported in research, its contested place in the current classification, and how RERAs are defined — are drawn from: Guilleminault et al., Chest (1993); Bao & Guilleminault, Current Opinion in Pulmonary Medicine (2004); de Godoy et al., Sleep Science (2015); the StatPearls clinical reference on upper airway resistance syndrome; the AASM Manual for the Scoring of Sleep and Associated Events; and the American Academy of Sleep Medicine's ICSD-3 classification (2014).
Everything about how the nights felt, and what I wish I'd asked sooner, is my personal interpretation of my own experience — not medical advice. I'm not a doctor. Please talk to a sleep specialist about anything here that resonates.