NREM sleep EEG slow waves in autistic and typically developing children: Morphological characteristics and scalp distribution

Abstract

Summary Autism is a developmental disorder with a neurobiological aetiology. Studies of the autistic brain identified atypical developmental trajectories that may lead to an impaired capacity to modulate electroencephalogram activity during sleep. We assessed the topography and characteristics of non‐rapid eye movement sleep electroencephalogram slow waves in 26 boys aged between 6 and 13 years old: 13 with an autism spectrum disorder and 13 typically developing. None of the participants was medicated, intellectually disabled, reported poor sleep, or suffered from medical co‐morbidities. Results are derived from a second consecutive night of polysomnography in a sleep laboratory. Slow waves (0.3–4.0 Hz; >75 µV) were automatically detected on artefact‐free sections of non‐rapid eye movement sleep along the anteroposterior axis in frontal, central, parietal and occipital derivations. Slow wave density (number per minute), amplitude (µV), slope (µV s−1) and duration (s) were computed for the first four non‐rapid eye movement periods. Slow wave characteristics comparisons between groups, derivations and non‐rapid eye movement periods were assessed with three‐way mixed ANOVAs. Slow wave density, amplitude, slope and duration were higher in anterior compared with most posterior derivations in both groups. Children with autism spectrum disorder showed lower differences in slow waves between recording sites along the anteroposterior axis than typically developing children. These group differences in the topography of slow wave characteristics were stable across the night. We propose that slow waves during non‐rapid eye movement sleep could be an electrophysiological marker of the deviant cortical maturation in autism linked to an atypical functioning of thalamo‐cortical networks.

Reduced sleep pressure in young children with autism

“…Nevertheless, one may expect that reduced SWA would be apparent in smaller proportions of SWS (stage N3). This was indeed reported by some PSG studies [22][23][24][25] , but not others [26][27][28] . Note that in our results, the proportion of SWS was not significant different across groups when examining the entire sleep period (Table 2).…”

“…Poor sleep in children with ASD is associated with increased sensory sensitivities [15][16][17][18] and increased aberrant behaviors [18][19][20][21] , which impair the quality of life of affected families 14 . PSG studies have corroborated the existence of sleep disturbances in children with ASD [22][23][24][25][26][27][28] , but have yielded mixed results regarding potential abnormalities in sleep architecture. While some have reported that children with ASD exhibit decreased slow wave sleep (SWS, stage N3) [22][23][24][25] or rapid eye movement (REM) 11,22,28 durations, others have not 23,[26][27][28] .…”

“…PSG studies have corroborated the existence of sleep disturbances in children with ASD [22][23][24][25][26][27][28] , but have yielded mixed results regarding potential abnormalities in sleep architecture. While some have reported that children with ASD exhibit decreased slow wave sleep (SWS, stage N3) [22][23][24][25] or rapid eye movement (REM) 11,22,28 durations, others have not 23,[26][27][28] .…”

Sleep problems in preschoolers with autism spectrum disorders are associated with sensory sensitivities and thalamocortical overconnectivity

“…Arazi et al, 2019;Farmer et al, 2018;Lehoux et al, 2019;Page et al, 2020). Particularly, atypical slow wave activity (Arazi et al 2019;Lehoux et al 2019) and reduced sleep spindle generation (Farmer et al 2018) as observed with EEG in young children with ASD has been associated with altered thalamocortical FC during deep sleep (Baran et al 2019). This is, however, fully consistent with our conclusion of sleep problems in ASD being associated with atypical auditory-thalamic FC and sensory sensitivities.…”

“…This is supported by a number of EEG studies showing atypical sleep architecture in young children with ASD (e.g. Arazi et al, 2019;Farmer et al, 2018;Lehoux et al, 2019;Page et al, 2020). Particularly, atypical slow wave activity (Arazi et al 2019;Lehoux et al 2019) and reduced sleep spindle generation (Farmer et al 2018) as observed with EEG in young children with ASD has been associated with altered thalamocortical FC during deep sleep (Baran et al 2019).…”