Slow-wave activity surrounding stage N2 K-complexes and daytime function measured by psychomotor vigilance test in obstructive sleep apnea

Abstract

Study Objective: To better understand the inter-individual differences in neurobehavioral impairment in obstructive sleep apnea (OSA) and its treatment with continuous positive airway pressure (CPAP), we examined how changes in sleep electroencephalography (EEG) slow waves were associated with next-day psychomotor vigilance test (PVT) performance.Methods: Data from 28 OSA subjects (Apnea-Hypopnea Index with 3% desaturation and/or with an associated arousal [AHI3A] > 15/hour; AHI3A = sum of all apneas and hypopneas with 3% O 2 desaturation and/or an EEG arousal, divided by total sleep time [TST]), who underwent three full in-lab nocturnal polysomnographies (NPSGs: chronic OSA, CPAP-treated OSA, and acute OSA), and 19 healthy sleepers were assessed. Four 20-minute PVTs were performed after each NPSG along with subjective and objective assessment of sleepiness. Three EEG metrics were calculated: K-complex (KC) Density (#/minute of N2 sleep), change in slow-wave activity in 1-second envelopes surrounding KCs (ΔSWAK), and relative frontal slow-wave activity during non-rapid eye movement (NREM) (%SWA).Results: CPAP treatment of OSA resulted in a decrease in KC Density (chronic: 3.9 ± 2.2 vs. treated: 2.7 ± 1.1; p < 0.01; mean ± SD) and an increase in ΔSWAK (chronic: 2.6 ± 2.3 vs. treated: 4.1 ± 2.4; p < 0.01) and %SWA (chronic: 20.9 ± 8.8 vs. treated: 26.6 ± 8.6; p < 0.001). Cross-sectionally, lower ΔSWAK values were associated with higher PVT Lapses (chronic: rho = −0.55, p < 0.01; acute: rho = −0.46, p = 0.03). Longitudinally, improvement in PVT Lapses with CPAP was associated with an increase in ΔSWAK (chronic to treated: rho = −0.48, p = 0.02; acute to treated: rho = −0.5, p = 0.03). In contrast, OSA severity or global sleep quality metrics such as arousal index, NREM, REM, or TST were inconsistently associated with PVT Lapses. Conclusion:Changes in EEG slow waves, in particular ΔSWAK, explain inter-individual differences in PVT performance better than conventional NPSG metrics, suggesting that ΔSWAK is a night-time correlate of next-day vigilance in OSA.

Current Management of Residual Excessive Daytime Sleepiness Due to Obstructive Sleep Apnea: Insights for Optimizing Patient Outcomes

“…The repeated arousal-induced sleep fragmentation that occurs in patients with OSA can alter the cyclic structure of sleep [ 26 ]. Sleep fragmentation and the hypoxia–reoxygenation cycle may induce inflammation and oxidative stress that may alter the health of wake-activating neurons [ 27 , 28 ]. OSA potentially shifts the peak in melatonin secretion [ 29 ] and induces fragmented sleep, which may reduce the efficiency of the glymphatic transport system that is proposed to be important for waste removal in the central nervous system during sleep (Fig.…”

“…Interestingly, this MRI study showed that several different brain regions, particularly the cerebellum, experienced diffusion changes at different phases of the sleep–wake cycle, suggesting a more complex rhythm in humans than in rodents [ 52 ]. Further research is needed to determine whether alterations in slow-wave sleep patterns in patients with OSA [ 28 ] cause changes in brain accelerated diffusion dynamics or the efficiency of waste removal.…”

New and Emerging Approaches to Better Define Sleep Disruption and Its Consequences

“…Abnormal K-complex morphology (lower amplitude) and lower K-complex density (# per minutes) have been associated with the progression of amnestic mild cognitive impairment (pre-clinical phase of Alzheimer's disease) in ∼70 patients (Liu et al, 2020). Abnormal K-complex morphology has also been associated with greater lapses in next-day alertness as measured using a psychomotor vigilance task (Parekh et al, 2019(Parekh et al, , 2021. At a population level, cross-sectional studies have suggested that a decrease in K-complex density may be a biomarker of sleep disorders, such as sleep apnea (Lechat et al, 2020).…”

Association between obstructive sleep apnea and male serum testosterone: A systematic review and meta‐analysis

“…Specifically, OSA can increase daytime sleepiness and decrease psychomotor performance, subsequently reducing the quality of life. 41 Furthermore, untreated OSA was associated with metabolic diseases, cardiovascular and cerebrovascular diseases, and other diseases, increasing the risk of death among middle-aged and elderly people. 42 Thus, OSA has attracted the attention of public health research.…”