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Moderate-to-severe obstructive sleep apnea is associated with selective prolongation of the long-latency reflex component LLR2, indicating altered cortical sensorimotor processing.

In a study of 39 OSA patients and 21 healthy controls, LLR2 latency was significantly prolonged in moderate-to-severe OSA compared to controls (53.1 vs. 50.4 ms, p=0.014). This effect remained significant after adjusting for age and BMI (F=3.686, p=0.032), suggesting a selective slowing of cortical sensorimotor integration in more severe OSA.

Last updated: Jul 10, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score32/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Selective prolongation of the long-latency reflex component in obstructive sleep apnea: Evidence for cortical sensorimotor slowing.

observational

Türkmen N, Akbal Çufalı Ş, Taş ÖF, Yurtsever Kum N · Sleep & breathing = Schlaf & Atmung (2026)

Participants: N/A
Duration: N/A
Intervention: Standardized median nerve stimulation at the wrist during sustained contraction of abductor pollicis brevis.
Outcome: LLR2 onset latency and H-LLR2 interval.
Effect Size: N/A
Population: 39 patients with polysomnography-confirmed obstructive sleep apnea and 21 healthy controls.

Result:

PubMed: 42377633DOI: 10.1007/s11325-026-03753-5

Study 2. Obstructive sleep apnea is associated with disturbances in nutrition-related biochemical markers among eutrophic adults: Findings from the EPISONO cohort.

observational

Schimenes BC, Alvarenga TA, Morelhão PK, Porcacchia AS, Tufik SB, Tufik S, Andersen ML · Sleep medicine (2026)

Participants: N/A
Duration: N/A
Intervention: None (observational study comparing OSA severity groups)
Outcome: Nutrition-related biochemical markers (VLDL, triglycerides, zinc, magnesium)
Effect Size: N/A
Population: Eutrophic adults aged 20-59 years from the EPISONO cohort in São Paulo

Result:

PubMed: 41955724DOI: 10.1016/j.sleep.2026.108945

Mechanism Graph

Obstructive sleep apnea causes intermittent hypoxia and sleep fragmentation.
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These factors may impair cortical sensorimotor integration pathways.
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LLR2 is a long-latency reflex mediated by transcortical sensorimotor loops.
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Selective prolongation of LLR2 latency indicates slowed cortical processing in moderate-to-severe OSA.

Limitations

  • ⚠The association between LLR2 latency and minimum oxygen saturation in mild OSA did not persist after adjustment for age and BMI.
  • ⚠The study is exploratory with a relatively small sample size and requires validation in larger prospective cohorts.

Frequently Asked Questions

What is LLR2 and why is it relevant to sleep apnea?▼

LLR2 is a long-latency reflex component that reflects cortical sensorimotor integration. Its prolongation in moderate-to-severe OSA suggests slowed neural processing, which may relate to neurocognitive impairment.

Did the study find any differences in other reflex components?▼

No, H-reflex, LLR1, and LLR3 latencies did not differ significantly between OSA patients and controls, indicating the effect is selective to LLR2.

Was the LLR2 prolongation independent of age and BMI?▼

Yes, after adjusting for age and BMI, the group effect on LLR2 latency remained significant (p=0.032), though the H-LLR2 interval was no longer significant.

Could LLR testing be used clinically for OSA?▼

The authors suggest LLR testing may be a simple exploratory neurophysiological complement to conventional sleep metrics, but validation in larger studies is needed before clinical use.

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References

  1. 1.Türkmen N, Akbal Çufalı Ş, Taş ÖF, Yurtsever Kum N. "Selective prolongation of the long-latency reflex component in obstructive sleep apnea: Evidence for cortical sensorimotor slowing.." Sleep & breathing = Schlaf & Atmung, 2026. PMID: 42377633 DOI: 10.1007/s11325-026-03753-5
  2. 2.Schimenes BC, Alvarenga TA, Morelhão PK, Porcacchia AS, Tufik SB, Tufik S, Andersen ML. "Obstructive sleep apnea is associated with disturbances in nutrition-related biochemical markers among eutrophic adults: Findings from the EPISONO cohort.." Sleep medicine, 2026. PMID: 41955724 DOI: 10.1016/j.sleep.2026.108945
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