Evaluation of the first-night effect of polysomnographic recording on cardiac autonomic activity in children with autism spectrum disorder

Introduction. The first night effect (FNE) is the tendency to have lower than usual sleep quality and quantity during the first polysomnography (PSG) recording, which alters sleep architecture. The FNE occurs in autism spectrum disorder (ASD), with studies suggesting that cardiac autonomic dysregulation is altered in patients with this illness. Objective. To determine whether the FNE influences the autonomic activity of ASD and typically developing (TD) children. Method. Two PSGs were recorded in 13 ASD and 13 TD children. The FNE was evaluated with eight sleep variables and autonomic activity through respiratory sinus arrhythmia (RSA) and low frequency (LF). Statistical analyses included intra- and inter-subject comparisons. Results. The FNE was present in both groups and affected more sleep variables in the ASD group. There were no significant differences between both recordings in RSA and LF. Inter-subject comparison showed significant differences in certain sleep variables, mainly during the first night. A comparison of RSA and LF between N2 and N3 stages and REM sleep showed that the TD group had significant differences in both measures whereas the ASD group only did so in the LF the first night. Discussion and conclusion. The influence of the FNE on the quantitative characteristics of sleep is corroborated in ASD and TD children, but not in RSA or LF. When the activity of the RSA and LF between sleep stages was considered, a different pattern was observed between the two PSG recordings.

Disturbed nighttime sleep in children and adults with rhythmic movement disorder

Study Objectives Rhythmic movements (RMs) during sleep are frequent and often considered as benign in children. Disabling forms are diagnosed as RM disorder and may persist in adulthood. Whether RMs severely impact sleep architecture in patients with RM disorder remain unclear. We performed a case–control study to characterize the clinical and polysomnographic patterns of children and adults with a diagnosis of RM disorder in comparison to controls, and to assess the associations between the RMs and the sleep architecture. Methods All consecutive patients (n = 50; 27 children, 35 males) with RM disorder from a single sleep clinic (from 2006 to 2019) underwent a comprehensive clinical evaluation and a polysomnographic recording in comparison to 75 controls (42 children and 53 males). Results About 82% of children and adult patients had a complaint of disturbed nighttime sleep. Comorbid neurodevelopmental, affective or sleep disorders were found in 92% of patients. While RM sequences defined by video polysomnographic criteria were observed in 82% of patients (in wakefulness and in all sleep stages), no similar sequences were observed in controls. Patients had altered sleep continuity, with low sleep efficiency, increased wake time after sleep onset, and frequent periodic leg movements and apnea events. The severity of RMs was associated with disrupted nighttime sleep, even after controlling for comorbid motor and respiratory events. Conclusions RM disorder is a rare, highly comorbid and disabling condition both in children and adults with frequent disturbed nighttime sleep that may contribute to the burden of the disease.

Striatal histamine mechanism in the pathogenesis of restless legs syndrome

Study Objectives Restless legs syndrome (RLS) has been hypothesized to be generated by abnormal striatal dopamine transmission. Dopaminergic drugs are effective for the treatment of RLS. However, long-term use of dopaminergic drugs causes adverse effects. We used iron-deficient (ID) and iron-replacement (IR) rats to address the neuropathology of RLS and to determine if a histamine H3 receptor (H3R) antagonist might be a useful treatment. Histamine H3R antagonists have been shown to decrease motor activity. Methods Control and ID rats were surgically implanted with electrodes for polysomnographic recording. After 3 days of baseline polysomnographic recordings, rats were systemically injected with the H3R agonist, α-methylhistamine, and antagonist, thioperamide. Recordings were continued after drug injection. Striatal H3R levels from control, ID, and IR rats were determined by western blots. Blood from control, ID, and IR rats was collected for the measurement of hematocrit levels. Results α-Methylhistamine and thioperamide increased and decreased motor activity, respectively, in control rats. In ID rats, α-methylhistamine had no effect on motor activity, whereas thioperamide decreased periodic leg movement (PLM) in sleep. Sleep–wake states were not significantly altered under any conditions. Striatal H3R levels were highest in ID rats, moderate to low in IR rats, and lowest in control rats. Striatal H3R levels were also found to positively and negatively correlate with PLM in sleep and hematocrit levels, respectively. Conclusions A striatal histamine mechanism may be involved in ID anemia-induced RLS. Histamine H3R antagonists may be useful for the treatment of RLS.

Parietal Fast Sleep Spindle Density Decrease in Alzheimer’s Disease and Amnesic Mild Cognitive Impairment

Several studies have identified two types of sleep spindles: fast (13–15 Hz) centroparietal and slow (11–13 Hz) frontal spindles. Alterations in spindle activity have been observed in Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI). Only few studies have separately assessed fast and slow spindles in these patients showing a reduction of fast spindle count, but the possible local specificity of this phenomenon and its relation to cognitive decline severity are not clear. Moreover, fast and slow spindle density have never been assessed in AD/MCI. We have assessed fast and slow spindles in 15 AD patients, 15 amnesic MCI patients, and 15 healthy elderly controls (HC). Participants underwent baseline polysomnographic recording (19 cortical derivations). Spindles during nonrapid eye movements sleep were automatically detected, and spindle densities of the three groups were compared in the derivations where fast and slow spindles exhibited their maximum expression (parietal and frontal, resp.). AD and MCI patients showed a significant parietal fast spindle density decrease, positively correlated with Minimental State Examination scores. Our results suggest that AD-related changes in spindle density are specific for frequency and location, are related to cognitive decline severity, and may have an early onset in the pathology development.