Blindness affects the developmental trajectory of the sleeping brain.

Sleep plays a crucial role in brain development, sensory information processing, and consolidation. Sleep spindles are markers of these mechanisms as they mirror the activity of the thalamocortical circuits. Spindles can be subdivided into two groups, slow (10-13 Hz) and fast (13-16 Hz), which are each associated with different functions. Specifically, fast spindles oscillate in the high-sigma band and are associated with sensorimotor processing, which is affected by visual deprivation. However, how blindness influences spindle development has not yet been investigated. We recorded nap video-EEG of 50 blind/severely visually impaired (BSI) and 64 sighted children aged 5 months to 6 years old. We considered aspects of both macro- and micro-structural spindles. The BSI children lacked the evolution of developmental spindles within the central area. Specifically, young BSI children presented low central high-sigma and high-beta (25-30 Hz) event-related spectral perturbation and showed no signs of maturational decrease. High-sigma and high-beta activity in the BSI group correlated with clinical indices predicting perceptual and motor disorders. Our findings suggest that fast spindles are pivotal biomarkers for identifying an early developmental deviation in BSI children. These findings are critical for initial therapeutic intervention.

Sleep effects of Ketogenic diet in pediatric patients with migraine: Preliminary data of a prospective study.

OBJECTIVE/BACKGROUND: Ketogenic dietary therapies' effects on sleep have been poorly investigated up to date. Preliminary results of a prospective study aimed at evaluating possible sleep changes in pediatric patients with migraine treated with classic ketogenic diet are presented. PATIENTS/METHODS: Included patients were aged 14-18 years and had a diagnosis of chronic migraine. A customized classic ketogenic diet was drawn up for all patients and all participants underwent neurological, nutritional and subjective and objective sleep assessment at baseline and after three months of follow-up (standardized sleep questionnaires, polysomnography, actigraphy). RESULTS: The majority of patients reported an improvement in migraine symptoms and quality of life. As far as sleep effects, a possible sleep stabilization was evidenced according to actigraphic data, and polysomnographic data showed a slight increase in total sleep time and sleep efficiency together with a reduction in waking time during night and a trend of NREM stage 1 decrease and REM increase. CONCLUSIONS: Future analyses on a broader population are needed to shed light on the ketogenic dietary therapies' effects on sleep and future research should be devoted to identify influence of possible individual and diet characteristics, and biochemical related changes.

The effects of ketogenic dietary therapies on sleep: A scoping review.

Sleep problems are common in neurological conditions for which ketogenic dietary therapies (KDTs) are recognised as an effective intervention (drug-resistant epilepsy, autism spectrum disorder, and migraine). Given the composite framework of action of ketogenic dietary therapies, the prevalence of sleep disturbance, and the importance of sleep regulation, the present scoping review aimed at identifying and mapping available evidence of the effects of ketogenic dietary therapies on sleep. A comprehensive web-based literature search was performed retrieving publications published to June 2023 using PubMed and Scopus, yielding to 277 records. Twenty papers were finally selected and included in the review. Data were abstracted by independent coders. High variability was identified in study design and sleep outcome evaluation among the selected studies. Several changes in sleep quality and sleep structure under ketogenic dietary therapies were found, namely an improvement of overall sleep quality, improvement in the difficulty falling asleep and nighttime awakenings, improvement in daytime sleepiness and an increase of REM sleep. The relevance and possible physiological explanations of these changes, clinical recommendations, and future directions in the field are discussed.

The vision of dreams: from ontogeny to dream engineering in blindness.

The mechanisms involved in the origin of dreams remain one of the great unknowns in science. In the 21st century, studies in the field have focused on 3 main topics: functional networks that underlie dreaming, neural correlates of dream contents, and signal propagation. We review neuroscientific studies about dreaming processes, focusing on their cortical correlations. The involvement of frontoparietal regions in the dream-retrieval process allows us to discuss it in light of the Global Workspace theory of consciousness. However, dreaming in distinct sleep stages maintains relevant differences, suggesting that multiple generators are implicated. Then, given the strong influence of light perception on sleep regulation and the mostly visual content of dreams, we investigate the effect of blindness on the organization of dreams. Blind individuals represent a worthwhile population to clarify the role of perceptual systems in dream generation, and to make inferences about their top-down and/or bottom-up origin. Indeed, congenitally blind people maintain the ability to produce visual dreams, suggesting that bottom-up mechanisms could be associated with innate body schemes or multisensory integration processes. Finally, we propose the new dream-engineering technique as a tool to clarify the mechanisms of multisensory integration during sleep and related mental activity, presenting possible implications for rehabilitation in sensory-impaired individuals. The Theory of Proto-consciousness suggests that the interaction of brain states underlying waking and dreaming ensures the optimal functioning of both. Therefore, understanding the origin of dreams and capabilities of our brain during a dreamlike state, we could introduce it as a rehabilitative tool. CITATION: Vitali H, Campus C, De Giorgis V, Signorini S, Gori M. The vision of dreams: from ontogeny to dream engineering in blindness. J Clin Sleep Med. 2022;18(8):2051-2062.

Sensitive period for the plasticity of alpha activity in humans.

Visual experience is crucial for the development of neural processing. For example, alpha activity development is a vision-dependent mechanism. Indeed, studies report no alpha activity is present in blind adults. Nevertheless, studies have not investigated the developmental trajectory of this activity in infants and children with blindness. Here, we hypothesize that the difference in neural activity of blind compared to sighted subjects is: absent at birth, progressive with age, specifically occipital and linked to a gradual motor impairment. Therefore, we consider spectral power of resting-state EEG and its association with motor impairment indices, in blind subjects and in sighted controls between 0 and 11 years of age. Blind subjects show posterior alpha activity during the first three years of life, although weaker and slower maturing compared to sighted subjects. The first great differentiation between blind and sighted subjects occurs between 3 and 6 years of age. Starting in this period, reduced alpha activity increases the probability of motor impairment in blind subjects, likely because of impaired perception/interaction. These results show that visual experience mediates the neural mechanisms generating alpha oscillations during the first years of life, suggesting that it is a sensitive period for the plasticity of this process.