Difference in spectral power density of sleep EEG between patients with simple snoring and those with obstructive sleep apnoea

Abstract

Patients with simple snoring (SS) often complain of poor sleep quality despite a normal apnoeahypopnoea index (AHI). We aimed to identify the difference in power spectral density of electroencephalography (EEG) between patients with SS and those with obstructive sleep apnoea (OSA). We compared the absolute power spectral density values of standard EEG frequency bands between the SS (n = 42) and OSA (n = 129) groups during the non-rapid eye movement (NREM) sleep period, after controlling for age and sex. We also analysed partial correlation between AHI and the absolute values of the EEG frequency bands. The absolute power spectral density values in the beta and delta bands were higher in the OSA group than in the SS group. AHI also positively correlated with beta power in the OSA group as well as in the combined group (OSA + SS). In conclusion, higher delta and beta power during NREM sleep were found in the OSA group than in the SS group, and beta power was correlated with AHI. These findings are microstructural characteristics of sleep-related breathing disorders.Obstructive sleep apnoea (OSA) is the most prevalent manifestation of sleep disordered breathing (SDB) characterised by repeated episodes of complete or partial collapse of upper airway during sleep 1 . Clinical manifestation of OSA includes snoring, disturbed sleep, fatigue, daytime sleepiness, loss of concentration, memory decline, and neuropsychiatric symptoms 2-5 . OSA is diagnosed using overnight polysomnography (PSG) when the apnoea or hypopnoea occurs five or more times per hour (apnoea-hypopnoea index [AHI] ≥ 5) 6 . In the spectrum of SDB, snorers with AHI < 5 are defined as having simple snoring (SS), which has less pathological and clinical significance 7-9 .SS is a preclinical condition that requires no treatment. However, patients with SS may suffer from daytime sleepiness, insomnia, and psychiatric symptoms despite a normal AHI 10,11 . Although SS is differentiated from OSA by AHI on PSG, there is a weak association between AHI and symptomatology in SDB [12][13][14][15][16][17][18] . Some studies reported that patients with SS have more severe psychiatric symptoms and poorer subjective sleep quality than those with OSA 12,19 . This paradoxical association between AHI, subjective sleep quality, and psychiatric symptoms suggests that other factors besides AHI influence such symptoms, and it may be necessary to study differences in microstructure in addition to classical PSG measurements (e.g., sleep stage ratio or sleep efficiency) and macrostructures.Researchers have previously attempted to investigate the microstructure of PSG-derived sleep as well as waking quantitative electroencephalography (qEEG) in SDB 20-24 . It has been generally accepted that wake EEG slowing is more pronounced in patients with OSA than in good sleepers, and the slowing is associated with

EEG Power Spectral Analysis of Abnormal Cortical Activations During REM/NREM Sleep in Obstructive Sleep Apnea

“…This demonstrates a shift in relative power contribution from the higher frequencies to the lower frequencies, i.e., the delta band, in the severe OSA patients. This is in agreement with previous EEG studies on OSA patients showing an increase in delta power during sleep (38,39) and wakefulness (34). The methodology of computing normalized EEG power, however, allowed this paper to provide a more detailed analysis of the change in the relative importance of each power band, specifically, showing the relatively reduced spectral power in faster frequencies in NREM sleep, which previous studies failed to reveal.…”

“…That is, OSA patients who suffered from more severe hypoxia during the night exhibited higher spectral power in the delta frequency band. This is supported by previous studies, which demonstrated an increase in delta spectral power (40,41) and a decrease in beta power (38) in healthy volunteers under hypoxia conditions [see however a mouse study showing contrary results (42)]. In terms of sleep fragmentation, it was found that frontal delta spectral power in NREM sleep was positively correlated with the patients' arousal index and negatively correlated with the proportion of time in N3 sleep.…”

Caffeine reverses the unconsciousness produced by light anesthesia in the continued presence of isoflurane in rats

“…Other studies have shown that respiration can impact EEG spectral frequencies [ 45 , 46 ]. In this study, caffeine altered respiration for a brief period of time after injection (see Table 1 ), which raises the possibility that EEG changes may result from alterations in respiration.…”

Sleep structure and electroencephalographic spectral power of middle‐aged or older adults: Normative values by age and sex in the Korean population

“…Reported abnormalities in spectral power analysis involve decreased absolute delta, theta and sigma power and increased beta power during NREM sleep (Ondze et al., 2003). However, inconsistencies are noted, with some reports showing an increased absolute delta activity during NREM sleep (Kang et al., 2020), whereas others show no differences across all frequency bands between OSA subjects and controls for either NREM or REM sleep (Jones et al., 2014). OSA severity also affects sleep microstructure, with increased EEG power across 0.5–32 Hz during REM sleep and an isolated increase in beta power during NREM sleep in men (Appleton et al., 2019).…”