“…In spontaneous activity, neural complexity tends to decrease when conscious processing is reduced, such as during propofol anaesthesia (Medel et al, 2022; Schartner et al, 2015; Varley et al, 2021), deep sleep (Abásolo et al, 2015; Andrillon et al, 2016; Mateos et al, 2018; Nicolaou & Georgiou, 2011), and epileptic seizures (Mateos et al, 2018). In sleep in particular, complexity of neural activity decreases compared to wakefulness (Abásolo et al, 2015; Andrillon et al, 2016; González et al, 2022; Mateos et al, 2018; Nicolaou & Georgiou, 2011), and it is lower in non‐rapid eye movement (NREM) than in rapid eye movement (REM) sleep (Abásolo et al, 2015; Andrillon et al, 2016; Mateos et al, 2018; Nicolaou & Georgiou, 2011). The reduction in complexity of spontaneous EEG signals during NREM sleep relative to wakefulness or REM may be due to slow wave activity (0.5–4 Hz), which exhibits strong stereotypical patterns (Adamantidis et al, 2019; González et al, 2022; Massimini et al, 2004).…”