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Figure 2 | Critical Care

Figure 2

From: Intensive care unit depth of sleep: proof of concept of a simple electroencephalography index in the non-sedated

Figure 2

Boxplots of the gamma (2A) and delta (2B) PSD. The power spectral densities for the R&K stages from the same recording used for Figure 1 (one of the 15 recordings of normal sleep) show the unique spectral composition of different sleep stages and the wake EEG. The central mark of the boxplots represents the median value; the boxes extend to the 25th and 75th percentile. The confidence intervals extend to a maximum of +/- 2.7 SD. All points outside this range are displayed as outliers, as red plusses. As sleep deepens (towards N4) delta PSD increases at the cost of gamma PSD, with the exception of REM sleep. EEG, electroencephalogram; R&K, Rechtschaffen and Kales; PSD, power spectral density; REM, rapid eye movement; SD, standard deviation.

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Critical Care

ISSN: 1364-8535