Effectiveness of Visual vs. Acoustic Closed-Loop Stimulation on EEG Power Density during NREM Sleep in Humans.

Konstantin V Danilenko,Sergei V Yarosh,Polina V Miroshnikova,Grigorii R Khazankin,Evgenii Kobelev,Ivan V Brack,Lyubomir I Aftanas

doi:10.3390/clockssleep2020014

Konstantin V Danilenko, Sergei V Yarosh + Show 5 more

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https://doi.org/10.3390/clockssleep2020014

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Abstract

The aim of the study was to investigate whether visual stimuli have the same potency to increase electroencephalography (EEG) delta wave power density during non-rapid eye movement (NREM) sleep as do auditory stimuli that may be practical in the treatment of some sleep disturbances. Nine healthy subjects underwent two polysomnography sessions—adaptation and experimental—with EEG electrodes positioned at Fz–Cz. Individually adjusted auditory (pink noise) and visual (light-emitting diode (LED) red light) paired 50-ms signals were automatically presented via headphones/eye mask during NREM sleep, shortly (0.75–0.90 s) after the EEG wave descended below a preset amplitude threshold (closed-loop in-phase stimulation). The alternately repeated 30-s epochs with stimuli of a given modality (light, sound, or light and sound simultaneously) were preceded and followed by 30-s epochs without stimulation. The number of artifact-free 1.5-min cycles taken in the analysis was such that the cycles with stimuli of different modalities were matched by number of stimuli presented. Acoustic stimuli caused an increase (p < 0.01) of EEG power density in the frequency band 0.5–3.0 Hz (slow waves); the values reverted to baseline at post-stimuli epochs. Light stimuli did not influence EEG slow wave power density (p > 0.01) and did not add to the acoustic stimuli effects. Thus, dim red light presented in a closed-loop in-phase fashion did not influence EEG power density during nocturnal sleep.

Highlights

Real-time modulation of sleep is an area of research targeted to modify/normalize architecture, duration, and/or depth of sleep by external stimuli, especially important in conditions characterized by sleep disturbances, such as psychophysiological insomnia and depression.The two distinct states of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep have their own neuroanatomic, electrophysiological, and behavioral characteristics
NREM is characterized by electroencephalography (EEG) that shows high-voltage K-complexes and sleep spindles in shallow sleep and high-voltage slow waves (0.5–2 Hz, amplitude above 75 μV) in deep, “slow-wave” sleep [1]
NREM is followed by REM, with 4–5 of such cycles over the sleep episode, and the proportion of REM increasing towards the end of the night [2]

Summary

Introduction

Real-time modulation of sleep is an area of research targeted to modify/normalize architecture, duration, and/or depth of sleep by external stimuli, especially important in conditions characterized by sleep disturbances, such as psychophysiological insomnia and depression.The two distinct states of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep have their own neuroanatomic, electrophysiological, and behavioral characteristics. NREM is characterized by electroencephalography (EEG) that shows high-voltage K-complexes and sleep spindles in shallow sleep (stage N2) and high-voltage slow waves (0.5–2 Hz, amplitude above 75 μV) in deep, “slow-wave” sleep (stage N3) [1]. REM is characterized by low amplitude, mixed frequency EEG without K-complexes or sleep spindles [1]. EEG power density is denoted as “slow wave activity” (SWA) in the frequency band 0.5–4 Hz (subdivided further on slow oscillation 0.5–1 Hz and delta waves 1–4 Hz) and “spindle activity” in the 9–15 Hz band (subdivided further on slow spindle 9–12 Hz and fast spindle 12–15 Hz) [6]. The increase in SWA is accompanied by a decrease in spindle band power density that is known to be characteristic for (deeper) sleep [7]

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