Neurology of Sleep

Self-reported quantity and quality of sleep in children and adolescents with a chronic condition compared to healthy controls

To assess self-reported quantity and quality of sleep in Dutch children with a chronic condition compared to healthy controls and to the recommended hours of sleep for youth. Sleep quantity and quality were analyzed in children with a chronic condition (cystic fibrosis, chronic kidney disease, congenital heart disease, (auto-)immune disease, and medically unexplained symptoms (MUS); n = 291; 15 ± 3.1 years, 63% female. A subset of 171 children with a chronic condition were matched to healthy controls using Propensity Score matching, based on age and sex, ratio 1:4. Self-reported sleep quantity and quality were assessed with established questionnaires. Children with MUS were analyzed separately to distinguish between chronic conditions with and without an identified pathophysiological cause. Generally, children with a chronic condition met the recommended amount of sleep, however 22% reported poor sleep quality. No significant differences in sleep quantity and quality were found between the diagnosis groups. Children with a chronic condition and with MUS slept significantly more than healthy controls at ages 13, 15, and 16. Both at primary and secondary school, poor sleep quality was least frequent reported in children with a chronic condition and most often reported in children with MUS.  Conclusion: Overall, children with chronic conditions, including MUS, met the recommended hours of sleep for youth, and slept more than healthy controls. However, it is important to obtain a better understanding of why a substantial subset of children with chronic conditions, mostly children with MUS, still perceived their sleep quality as poor. What is Known: • According to the Consensus statement of the American Academy of Sleep medicine, typically developing children (6 to 12 years) should sleep 9 to 12 h per night, and adolescents (13 to 18 years) should sleep 8 to 10 h per night. • Literature on the optimal quantity and quality of sleep in children with a chronic condition is very limited. What is New: Our findings are important and provide novel insights: • In general, children with a chronic condition sleep according to the recommended hours of sleep. • A substantial subset of children with chronic conditions, perceived their sleep quality as poor. Although this was reported mostly by children with medically unexplained symptoms (MUS), the found poor sleep quality was independent of specific diagnosis.

Modulation of sleep behavior in zebrafish larvae by pharmacological targeting of the orexin receptor

New pharmacological approaches that target orexin receptors (OXRs) are being developed to treat sleep disorders such as insomnia and narcolepsy, with fewer side effects than existing treatments. Orexins are neuropeptides that exert excitatory effects on postsynaptic neurons via the OXRs, and are important in regulating sleep/wake states. To date, there are three FDA-approved dual orexin receptor antagonists for the treatment of insomnia, and several small molecule oral OX2R (OXR type 2) agonists are in the pipeline for addressing the orexin deficiency in narcolepsy. To find new hypnotics and psychostimulants, rodents have been the model of choice, but they are costly and have substantially different sleep patterns to humans. As an alternative model, zebrafish larvae that like humans are diurnal and show peak daytime activity and rest at night offer several potential advantages including the ability for high throughput screening. To pharmacologically validate the use of a zebrafish model in the discovery of new compounds, we aimed in this study to evaluate the functionality of a set of known small molecule OX2R agonists and antagonists on human and zebrafish OXRs and to probe their effects on the behavior of zebrafish larvae. To this end, we developed an in vitro IP-One Homogeneous Time Resolved Fluorescence (HTRF) immunoassay, and in vivo locomotor assays that record the locomotor activity of zebrafish larvae under physiological light conditions as well as under dark-light triggers. We demonstrate that the functional IP-One test is a good predictor of biological activity in vivo. Moreover, the behavioral data show that a high-throughput assay that records the locomotor activity of zebrafish throughout the evening, night and morning is able to distinguish between OXR agonists and antagonists active on the zebrafish OXR. Conversely, a locomotor assay with alternating 30 min dark-light transitions throughout the day is not able to distinguish between the two sets of compounds, indicating the importance of circadian rhythm to their pharmacological activity. Overall, the results show that a functional IP-one test in combination with a behavioral assay using zebrafish is well-suited as a discovery platform to find novel compounds that target OXRs for the treatment of sleep disorders.

Variation in the sexual behavior and blood count parameters induced by sleep deprivation in male rats

BACKGROUND

Sleep is a fundamental biological requirement, and lack of sleep has increasingly been recognized to cause metabolic consequences and adversely affect immune function. Recent articles have pointed to how sleep and sexual functions may be interlinked, involving inflammation, vascular alterations, tissue damage, and endothelial dysfunction.

OBJECTIVES

We examined the effect of paradoxical sleep deprivation (PSD) on sexual behavior and hemogram parameters in male rats. In addition, we also explored whether 7 days of recovery sleep is sufficient to offset these detriments.

MATERIALS AND METHODS

 Male rats were given sexual experience through training. At the 5th test, the sexually vigorous males were randomly separated into 3 experimental groups: PSD (rats submitted to 96 hours of PSD, n = 6), RS (recovery sleep 7 days after PSD, n = 6), and control (n = 10). We evaluated the sexual behaviors of three groups. Blood samples were collected to analysis hemogram parameters.

RESULTS

In this study, we recognized that repeated copulatory tests can lead to changes in sexual behavior over time. We found that 96 hours of acute sleep deprivation impaired the sexual behavior of male rats. Our results demonstrated that 96 hours of PSD also increased levels of white blood cell (WBC) subpopulations, in particular neutrophils. Recovery sleep after sleep deprivation has a certain reversal effect on WBC subgroups and impairment of sexual behavior, with some signs that not all levels were back to baseline even after 7 days of recovery.

CONCLUSION

In general, we found that 96 hours of PSD impaired the sexual behavior of male rats. Our results demonstrated that PSD can cause systemic inflammation by affecting WBC subpopulations, in particular neutrophils. 7 days of recovery sleep after sleep deprivation has a certain reversal effect to these impairments. This article is protected by copyright. All rights reserved.

Sleep Abnormalities in the Synaptopathies-SYNGAP1-Related Intellectual Disability and Phelan-McDermid Syndrome

Neurodevelopmental disorders are frequently associated with sleep disturbances. One class of neurodevelopmental disorders, the genetic synaptopathies, is caused by mutations in genes encoding proteins found at the synapse. Mutations in these genes cause derangement of synapse development and function. We utilized a validated sleep instrument, Children's Sleep Habits Questionnaire (CSHQ) to examine the nature of sleep abnormalities occurring in individuals with two synaptopathies-Phelan-McDermid syndrome (PMD) (N = 47, male = 23, female = 24, age 1-46 years) and SYNGAP1-related intellectual disability (SYNGAP1-ID) (N = 64, male = 31, female = 33, age 1-64 years), when compared with unaffected siblings (N = 61, male = 25, female = 36, age 1-17 years). We found that both PMD and SYNGAP1-ID have significant sleep abnormalities with SYNGAP1-ID having greater severity of sleep disturbance than PMD. In addition, sleep disturbances were more severe for PMD in individuals 11 years and older compared with those less than 11 years old. Individuals with either disorder were more likely to use sleep aids than unaffected siblings. In conclusion, sleep disturbances are a significant phenotype in the synaptopathies PMD and SYNGAP1-ID. Improved sleep is a viable endpoint for future clinical trials for these neurodevelopmental disorders.