In the last decades, a high increase in life expectancy not adequately balanced by an improvement in the quality of life has been observed, leading possibly to an increase in the prevalence of affective and cognitive disorders related to aging, such as depression, cognitive impairment, dementia and Alzheimer’s disease. As mental illnesses have multifactorial aetiologies, many modifiable factors including lifestyle and nutrition play an essential role. Among nutritional factors, intermittent fasting has emerged as an innovative strategy to prevent and treat mental health disorders, sleep disturbances and cognitive impairment. Among all types of intermittent fasting regimens, the time restricted feeding appears to be the most promising protocol as it allows to induce benefits of a total fasting without reducing global calories and nutrients intake. This review summarises the evidence on the effect of time restricted feeding towards brain health, emphasising its role on brain signalling, neurogenesis and synaptic plasticity.

REM sleep without atonia (RSWA) is the polysomnographic (PSG) hallmark of rapid eye movement (REM) sleep behavior disorder (RBD), a feature essential for the diagnosis of this condition. Several additional neurophysiological aspects of this complex disorder have also recently been investigated in depth, which constitute the focus of this narrative review, together with RSWA. First, we describe the complex neural network underlying REM sleep and its muscle atonia, focusing on the disordered mechanisms leading to RSWA. RSWA is then described in terms of its polysomnographic features, and the methods (visual and automatic) currently available for its scoring and quantification are exposed and discussed. Subsequently, more recent and advanced neurophysiological features of RBD are described, such as electroencephalography during wakefulness and sleep, transcranial magnetic stimulation, and vestibular evoked myogenic potentials. The role of the assessment of neurophysiological features in the study of RBD is then carefully discussed, highlighting their usefulness and sensitivity in detecting neurodegeneration in the early or prodromal stages of RBD, as well as their relationship with other proposed biomarkers for the diagnosis, prognosis, and monitoring of this condition. Finally, a future research agenda is proposed to help clarify the many still unclear aspects of RBD.

Orexin plays a significant role in the modulation of REM sleep, as well as in the regulation of appetite and feeding. This review explores, first, the current evidence on the role of orexin in the modulation of sleep and wakefulness and highlights that orexin should be considered essentially as a neurotransmitter inhibiting REM sleep and, to a much lesser extent, a wake promoting agent. Subsequently, the relationship between orexin, REM sleep, and appetite regulation is examined in detail, shedding light on their interconnected nature in both physiological conditions and diseases (such as narcolepsy, sleep-related eating disorder, idiopathic hypersomnia, and night eating syndrome). Understanding the intricate relationship between orexin, REM sleep, and appetite regulation is vital for unraveling the complex mechanisms underlying sleep-wake patterns and metabolic control. Further research in this field is encouraged in order to pave the way for novel therapeutic approaches to sleep disorders and metabolic conditions associated with orexin dysregulation.

Summary: The objective of this observational cohort study was to analyse the age‐related changes of periodic leg movements during sleep using the newest international scoring rules, to expand past analyses, including patients in the paediatric age range, and also to analyse the changes of short‐interval and isolated leg movements during sleep throughout the lifespan. One hundred and sixty‐five patients (84 women) with restless legs syndrome were recruited in the following age groups: 16 preschoolers (≤5 years of age), 29 school‐age children (6–12 years), 19 adolescents (13–17 years), 17 young adults (19–40 years), 47 adults (41–60 years) and 37 seniors (>60 years). Total, periodic, short‐interval and isolated leg movements during sleep and periodicity indexes were obtained by polysomnography. The total index showed (quartic polynomial interpolation) a decrease before 10 years, followed by a steady increase up to 30 years, a relatively stable period until 60 years, and a final increase up to 80 years. This course was almost entirely due to changes in periodic movements. Isolated movements did not change significantly and short‐interval movements showed only an increase in seniors. Our study indicates that, in restless legs syndrome, the total index shows a peculiar and unique course throughout the lifespan, mainly due to periodic movements. These age‐related changes may mirror developmental changes in network complexity known to occur in dopaminergic circuits. These data further confirm the need to better assess the periodicity of leg movements in sleep during the human development period, in order to obtain clinically useful information.