Sleep Apnea and Restless Legs: Two Studies, Two Answers
A review found restless legs in 10 to 30% of apnea patients and worse outcomes when both are present. A study of 8,852 patients found no association at all once it adjusted for the obvious confounders. Both are right, and the difference is the useful part.
Restless legs syndrome — the urge to move your legs at rest, worse in the evening, relieved by moving — turns up often in sleep clinics alongside obstructive sleep apnea. Whether that is a relationship or a coincidence has two recent answers that look contradictory.
Working out why they differ is more useful than either one alone.
The review that found a relationship
A 2025 systematic review, PRISMA-guided and PROSPERO-registered, pooled 10 observational studies covering more than 3,000 participants with comorbid restless legs and sleep apnea.
Restless legs prevalence among apnea patients ranged from 10% to 30%.
More usefully, having both was not neutral. Comorbidity was associated with increased rates of insomnia, fatigue and depression, and a reduced response to apnea therapy. And in multiple studies, CPAP treatment improved restless legs symptoms, including reduced medication use.
The study that found none
A 2025 analysis took 8,852 patients referred to a single hospital for suspected sleep apnea between 2011 and 2022. Everyone had respiratory polygraphy and completed a questionnaire establishing whether they had restless legs.
It then asked the question in both directions — does restless legs predict moderate-to-severe apnea, and does apnea severity predict restless legs — adjusting for sex, age, marital status, alcohol, smoking, caffeine after 5pm and BMI.
No association, either way.
Why do both results stand?
They are not measuring the same thing, and the distinction is worth internalising because it recurs everywhere in this field.
Prevalence is not association. Finding restless legs in 10–30% of apnea patients tells you how common it is in that population. It does not tell you whether apnea has anything to do with it — because restless legs is also common in the general population, more common with age, and much more common in people who end up at a sleep clinic for any reason.
The 8,852-patient study asked the harder question: among people all referred for suspected apnea, does having apnea make restless legs more likely once you account for the things that cause both? That answer was no.
So the honest synthesis is: the two conditions co-occur often, and there is no good evidence that one drives the other. They share a waiting room rather than a mechanism.
Evidence tier 1 that they frequently co-occur. Tier 1 that comorbidity predicts worse symptoms and poorer therapy response. Tier 3 for a causal link in either direction.
What actually matters if you have both
The causal question is academic. These two findings are not:
Comorbidity predicts a worse response to apnea treatment. If you are treated for apnea and feel less improvement than expected, untreated restless legs is a candidate explanation — and a treatable one. That is a concrete reason to mention leg symptoms to whoever manages your apnea.
CPAP improved restless legs symptoms in multiple studies, which is a genuinely useful and non-obvious finding. It is also consistent with adherence research in patients with comorbid restless legs. Do not assume you need a second treatment before the first has been given a fair run.
The symptom overlap causes real misattribution. Both conditions produce fragmented sleep, daytime fatigue and unrefreshing nights, and both get blamed on the other. Insomnia, fatigue and depression were all more common with both. If you have been told your apnea is treated and you still feel wrecked, the question is what else is fragmenting your night. Insomnia and apnea together, and why snoring and fatigue are not the same question.
Ask whether leg movements were recorded. A full polysomnogram can record periodic limb movements; a home respiratory study generally cannot. If your study was a home test and your legs are the problem, that was never going to show up. How to read your sleep study.
And the baseline still applies: witnessed breathing pauses, gasping arousals, waking unrefreshed or daytime sleepiness that more sleep does not fix point at testing. Snoring versus apnea.