Spectral Analysis of All-Night Sleep EEG in Healthy Adults

Abstract

Power and coherence spectra were computed from all-night sleep EEG records in 6 healthy adult subjects. Derivations were from F3, F4, P3, P4, O1, 02, T3, and T4 to the vertex (Cz). Records were conventionally scored into sleep stages. Average power per sleep stage was maximal at frequencies 0.4–6 c/s in stage 4, at 6–10 c/s in either stage 3 or stage 4, at 12–14 c/s in stage 2 and at 14–30 c/s in stage 1. The average power range from highest values in the lowest frequency band to lowest values in the highest frequency band showed marked differences between sleep stages: It was lowest (12–14 dB) in stage 1, followed by stage 2 (20–22 dB), and stage 3 (16–28 dB), and largest in stage 4 (29–32 dB). REM sleep (15–16 sB) was between stage 1 and 2. The waking state showed an average power range of 11–15 dB. Alpha power at 8–10 c/s in occipital and parietal leads was remarkably constant during sleep, i.e. independent of sleep stage. Coherence showed maximal values at 2–8 c/s in REM sleep, at 8–12 c/s in stage 4, at 12–17 c/s in either stage 3 or 4, and at 17–30 c/s again in stage REM. There was significant coherence increase at 2–8 and 17–30 c/s from NREM to REM sleep, most pronounced between parietal to vertex derivations. Overall coherence between both occipital-to-vertex, or between occipital and parietal-to-vertex derivations, was essentially higher than in the other derivations. The results, essentially, give a comprehensive phenomenology of the dynamic spectral structure of all-night sleep EEG. They suggest that the different brain states during sleep (e.g. stage 1 NREM vs. REM) which are associated with different functions (e.g. hypnagogic hallucinations vs. dreams) differ in EEG spectral parameters if coherence is considered. Likewise, they suggest that studies of automatic sleep staging based exclusively on EEG spectral parameters appear promising.

Spectral Structure and Brain Mapping of Human Alpha Activities in Different Arousal States

“…These results agree with those that propose the existence of various types of alpha in the sleep onset period [7,9,10] and confirm the presence of alpha bursts in REM sleep [12][13][14]. In addition, the present findings provide a statistical confirmation of a specific alpha microstructure depending on the physiological state.…”

“…Furthermore, the above-mentioned decrease was pronounced over the posterior regions, especially for the slow-alpha range, and was found not only in REM sleep but also in stage 1 sleep. Dumermuth et al [14] detected a sleep-stage-independent 8-10 Hz alpha power in the parietal and occipital areas, which increased only in the waking state, and concluded that alpha activity is essentially a waking state EEG component since it showed lower and very stable values between sleep stages. In any case, it seems evident that REM alpha responds differently to stimulation than does waking alpha [15], and although there are some works that claim the equivalent functionality of REM and wakefulness states according to coherent oscillations of thalamocortical networks [16], brainstem-controlled changes in input-output properties and neuromodulatory balance [17], and/or information processing [18], the two states should have their own neurobiological correlates [19] and different functions.…”

Reduced functional connectivity between cortical sources in five meditation traditions detected with lagged coherence using EEG tomography

“…Anokhin et al, 1999;Beaumont et al, 1978;Holz et al, 2008;Okuhata et al, 2009;Weiss et al, 2005), but also, increased coherence has been reported during sleep compared to wakefulness (e.g. Dumermuth et al, 1983;Kaminski et al, 1997;Nielsen et al, 1990). Thus, the global decrease of coherence during meditation in all our five groups suggests that meditation is not simply comparable to task execution or sleep.…”

Genetic analysis of sleep

“…Stage 3N is the deepest stage of sleep, and is composed of at least 20% slow, large-amplitude oscillations in the 0-to 4-Hz range known as delta waves; at its deepest points, this stage of sleep could consist of >50% delta waves. (Dumermuth et al 1983;Aeschbach and Borbely 1993). Depth of sleep is often characterized by the term ''delta power,'' which refers to the frequency and amplitude of the delta waves produced.…”