Research Article
Volume 12 Issue 3 - 2020
EEG Spindle and K-Complex Densities During N2 Sleep Increase with Age into Adulthood and are Uncorrelated to Baseline Autonomic Tone
Ahmad M Zrik1,2, Amalia G Namath1, Siddharth S Sivakumar1, Mohammed Ismail2 and Roberto F Galán3,4*
1Department of Neurosciences, School of Medicine, CWRU, Cleveland, Ohio, USA
2Epilepsy Center, University Hospitals Case Medical Center, Cleveland, Ohio, USA
3Department of Medicine, Division of Pulmonology, School of Medicine, CWRU, Cleveland, Ohio, USA
4Department of Electrical Engineering and Computer Science, School of Engineering, CWRU, Cleveland, Ohio, USA
*Corresponding Author: Roberto F Galán, Department of Medicine, Division of Pulmonology, School of Medicine, CWRU, Cleveland, Ohio, USA.
Received: February 25, 2020; Published: March 26, 2020


The non-rapid eye movement (NREM) sleep is considered a true resting state for the brain, yet the physiologic drivers of neural activity in this phase remain undetermined. Neural activity may be endogenously driven to compensate for minimal sensory stimulation, or by physiologic processes associated with development, or the autonomic tone. To address this issue, we examined brain activity and autonomic tone during stage 2, NREM sleep over a cohort of 93 subjects, from toddlers to young adults. Brain activity was quantified as total counts of EEG spindles and spontaneous K-complexes over 30 minutes of uninterrupted sleep. Autonomic tone during sleep was measured as baseline heart rate and amplitude of respiratory sinus arrhythmia.

Blood pressure was also measured at rest. On average, spindle and K-complex counts increased by 8 and 1 units, respectively, with each additional year of development. Furthermore, spindle and K-complex densities were strongly correlated even after adjusting for age, which suggests a common underlying mechanism. Across subjects, spindles were on average 15 times more abundant than spontaneous K-complexes. Gender did not significantly influence any of these trends. Regarding autonomic tone, spindles and K-complex densities were anticorrelated with baseline heart rate and positively correlated with blood pressure, but these correlations are explained by natural covariations with age. Finally, neither respiratory rate nor sinus arrhythmia correlated with spindle or K-complex density, after adjusting for age. These results collectively demonstrate that spindle and spontaneous K-complex densities increase progressively with age during development into adulthood and are unrelated to baseline autonomic tone.

Keywords: Non-REM Sleep; Heart Rate Variability; Children; Development


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Citation: Roberto F Galán., et al. “EEG Spindle and K-Complex Densities During N2 Sleep Increase with Age into Adulthood and are Uncorrelated to Baseline Autonomic Tone”. EC Neurology 12.4 (2020): 50-58.

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