The dynamics of cyclic-periodic phenomena during non-rapid and rapid eye movement sleep.

Sleep is a complex physiological state characterized by distinct stages, each exhibiting unique electroencephalographic patterns and physiological phenomena. Sleep research has unveiled the presence of intricate cyclic-periodic phenomena during both non-rapid eye movement and rapid eye movement sleep stages. These phenomena encompass a spectrum of rhythmic oscillations and periodic events, including cyclic alternating pattern, periodic leg movements during sleep, respiratory-related events such as apneas, and heart rate variability. This narrative review synthesizes empirical findings and theoretical frameworks to elucidate the dynamics, interplay and implications of cyclic-periodic phenomena within the context of sleep physiology. Furthermore, it invokes the clinical relevance of these phenomena in the diagnosis and management of sleep disorders.

Sex-based disparities in dopamine agonist response in patients with restless legs syndrome.

This study aimed to investigate sex-related differences in the response to ropinirole and pramipexole in patients with restless legs syndrome (RLS). By analysing clinical parameters and polysomnographic (PSG) findings, we sought to elucidate the potential factors related to sex disparities modulating treatment responses and sleep quality in RLS. A total of 41 drug-free patients with RLS, aged ≥18 years, underwent two consecutive nocturnal PSG recordings, without medication at baseline; before the second night, 26 patients received an oral dose of 0.25 mg pramipexole whereas 15 received 0.5 mg ropinirole. After each PSG recording, patients self-evaluated the severity of their previous night symptoms by means of an ad hoc visual analogue scale (VAS). At baseline, sleep efficiency and percentage of Stage N2 tended to be higher in females while wakefulness after sleep onset was significantly higher in males. After treatment, total leg movements during sleep (LMS), periodic LMS (PLMS), and periodicity indexes were significantly lower in females than in males. The VAS score was lower after treatment in all patients, without differences between the two sexes. This study demonstrates a higher acute responsiveness of PLMS to dopamine agonists (pramipexole and ropinirole) in females than in males with RLS. These findings might be explained by differential sex-related expression of dopamine receptors, especially D3, within the central nervous system. In addition, our findings provide translational hints toward a better tailored and sex-specific approach to the treatment of RLS associated with PLMS, with dopamine agonist possibly associated with a better outcome in females than in males.

COVID-19 and Mental Health: A "Pandemic Within a Pandemic".

The COVID-19 pandemic has brought significant changes in daily life for humanity and has had a profound impact on mental health. As widely acknowledged, the pandemic has led to notable increases in rates of anxiety, depression, distress, and other mental health-related issues, affecting both infected patients and non-infected individuals. COVID-19 patients and survivors face heightened risks for various neurological and psychiatric disorders and complications. Vulnerable populations, including those with pre-existing mental health conditions and individuals living in poverty or frailty, may encounter additional challenges. Tragically, suicide rates have also risen, particularly among young people, due to factors such as unemployment, financial crises, domestic violence, substance abuse, and social isolation. Efforts are underway to address these mental health issues, with healthcare professionals urged to regularly screen both COVID-19 and post-COVID-19 patients and survivors for psychological distress, ensuring rapid and appropriate interventions. Ongoing periodic follow-up and multidimensional, interdisciplinary approaches are essential for individuals experiencing long-term psychiatric sequelae. Preventive strategies must be developed to mitigate mental health problems during both the acute and recovery phases of COVID-19 infection. Vaccination efforts continue to prioritize vulnerable populations, including those with mental health conditions, to prevent future complications. Given the profound implications of mental health problems, including shorter life expectancy, diminished quality of life, heightened distress among caregivers, and substantial economic burden, it is imperative that political and health authorities prioritize the mental well-being of all individuals affected by COVID-19, including infected individuals, non-infected individuals, survivors, and caregivers.

Periodic leg movements during sleep and iron status in infants with prematurity, Down syndrome and Prader-Willi syndrome.

Sleep disturbances including bedtime problems and night awakenings are common during infancy. Polysomnography during the first years of life is performed mainly to rule out sleep-disordered breathing; however, sleep-related movement disorders can constitute a significant contributor to sleep disruption in this age group. Almost no studies have investigated the presence of periodic limb movements during sleep and underlying iron deficiency in infants, especially in those born preterm or with an underlying genetic syndrome. In this retrospective study we included infants 3-24 months referred for polysomnography for snoring or frequent nocturnal awakenings. All children had bloodwork (ferritin and haemoglobin) conducted within 3 months of the overnight sleep study. We studied 79 infants, including 31 (39.2%) full-term without diagnosis, 10 (12.7%) born premature, 16 (20.3%) with Down syndrome, 15 (19.0%) with Prader-Willi syndrome, and the remaining seven (8.9%) had various disorders. Compared with those with Down syndrome, Prader-Willi syndrome and full-term infants, those with prematurity showed a statistically significant elevated periodic limb movement index and lower ferritin levels than the other groups. Both ferritin (r = -0.18) and haemoglobin (r = -0.30) were negatively correlated with periodic limb movement index; however, this correlation reached statistical significance only for haemoglobin. Iron deficiency is associated with increased periodic leg movements during sleep in infants. Infants with prematurity had higher periodic limb movement index and lower ferritin levels than infants with Down syndrome, Prader-Willi syndrome or without diagnosis.

Restless Sleep Disorder (RSD): a New Sleep Disorder in Children. A Rapid Review.

PURPOSE OF REVIEW: Restless sleep disorder (RSD) is a recently identified pediatric sleep disorder characterized by frequent movements during sleep associated with daytime symptoms. In this review we summarize the expanding evidence of the clinical presentation of RSD, potential pathophysiology, associated comorbidities, and current treatment options that will help the pediatrician identify children with RSD in a timely manner. RECENT FINDINGS: RSD is diagnosed in 7.7% of children referred evaluated in a pediatric sleep center. Children with RSD present with frequent nightly movements during sleep for at least 3 months, and have daytime symptoms related to poor sleep quality including excessive sleepiness, hyperactivity, irritability among other symptoms. Current evidence shows an increased sympathetic predominance, increased NREM sleep instability, and iron deficiency, as well as increased prevalence in parasomnias and attention deficit hyperactivity disorder. Consensus diagnostic criteria were recently published to diagnose RSD and emergent evidence suggests that iron supplementation improves its nighttime and daytime symptoms.

Heart rate changes associated with the different types of leg movements during sleep in children, adolescents and adults with restless legs syndrome.

The objective of this study was to describe in detail the heart rate changes accompanying short-interval leg movements during sleep, periodic leg movements during sleep, and isolated leg movements during sleep in children and adolescents with restless legs syndrome, and to compare them with the same findings in adults with restless legs syndrome. We analysed time series of R-R intervals synchronized to the onset of short-interval leg movements during sleep, periodic leg movements during sleep or isolated leg movements during sleep that entailed an arousal during non-rapid-eye-movement sleep. We assessed cardiac activation based on the heart rate changes with respect to baseline during non-rapid-eye-movement sleep without leg movements. All types of leg movements recorded during sleep were accompanied by important heart rate changes also in children, with an overall impact similar to that observed in adults. In all age groups, heart rate changes accompanying short-interval leg movements during sleep were constituted by a tachycardia, without a subsequent relative bradycardia, that was instead evident for periodic leg movements during sleep and isolated leg movements during sleep. Moreover, an age-related decline of the relative bradycardia following the heart rate increase, in association with periodic leg movements during sleep and isolated leg movements during sleep, was observed. Our findings show that important heart rate changes accompany all leg movements during sleep at all ages in restless legs syndrome, with significant age-related differences. This information represents an important contribution to the ongoing scientific debate on the possibility and opportunity to treat periodic leg movements during sleep.

Time restricted feeding and mental health: a review of possible mechanisms on affective and cognitive disorders.

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.

The Triad of Sleep, Immunity, and Cancer: A Mediating Perspective.

The triadic interplay between sleep, immunity, and cancer represents a growing area of biomedical research with significant clinical implications. This review synthesizes the current knowledge on how sleep influences immune function, the immune system's role in cancer dynamics, and the direct connections between sleep patterns and cancer risk. After a comprehensive overview of the interrelationships among these three domains, the mechanisms of sleep in immune function are described, detailing how sleep regulates the immune system, the effects of sleep duration and quality on immune responses, and the underlying molecular and cellular mechanisms. Also, the complex relationship between immunity and cancer is explored, highlighting the immune system's role in cancer prevention and progression, immune surveillance, tumor microenvironment, and the implications of immunodeficiency and immune modulation on cancer risk. The direct connections between sleep and cancer are then described, presenting epidemiological evidence linking sleep patterns to cancer risk, biological mechanisms that influence cancer development, and the role of sleep disorders in cancer prognosis. The mediating role of sleep between immunity and cancer is highlighted, proposing hypothesized pathways, summarizing evidence from experimental and clinical studies, and evaluating the impact of sleep interventions on immune function and cancer outcomes. This review concludes by discussing the clinical implications and future directions, emphasizing the potential for sleep-based interventions in cancer prevention and treatment, the integration of sleep management in oncology and immunotherapy, and outlining a future research agenda. This agenda includes understanding the mechanisms of the sleep-immunity-cancer interplay, conducting epidemiological studies on sleep and cancer risk, assessing the impact of sleep management in cancer treatment protocols, exploring sleep and tumor microenvironment interactions, and considering policy and public health implications. Through a detailed examination of these interconnected pathways, this review underscores the critical importance of sleep in modulating immune function and cancer outcomes, advocating for interdisciplinary research and clinical strategies to harness this knowledge for improved health outcomes.

Age related disparities in sleep apnea diagnosis using a wearable device: Implications of 4% vs. 3% hypopnea scoring criteria.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) diagnosis relies on the Apnea-Hypopnea Index (AHI), with discrepancies arising from the 3% and 4% desaturation criteria. This study investigates age-related variations in OSA severity classification, utilizing data from 1201 adult patients undergoing Home Sleep Apnea Testing (HSAT) with SleepImage Ring@. METHODS: The study employs Bland-Altman analysis to compare AHI values obtained with the 3% and 4% desaturation criteria. Age-stratified analysis explores discrepancies across different age groups. RESULTS: The analysis reveals a systematic bias favoring the 3% criterion, impacting the quantification of apnea events. Age-specific patterns demonstrate diminishing agreement between criteria with increasing age. CONCLUSION: This comprehensive study underscores the importance of standardized criteria in OSA diagnosis. The findings emphasize age-specific considerations and ethical concerns, providing crucial insights for optimizing patient care and advancing sleep medicine practices.

Individualized approaches to pediatric chronic insomnia: Advancing precision medicine in sleep disorders.

The manifestations of chronic insomnia undergo age-related changes. In younger infants and children, behavioral insomnia emerges as the most prevalent form and typically responds to behavioral interventions. However, distinct clusters of clinical presentations suggest the presence of various phenotypes, potentially implicating the primary involvement of specific neurotransmitters. These conceptualizations, coupled with genetic studies on pleiotropy and polygenicity, may aid in identifying individuals at risk of persistent insomnia into adulthood and shed light on novel treatment options. In school-age children, the predominant presentation is sleep-onset insomnia, often linked with nighttime fears, anxiety symptoms, poor sleep hygiene, limit-setting issues, and inadequate sleep duration. The manifestations of insomnia in adolescence correlate with the profound changes occurring in sleep architecture, circadian rhythms, and homeostatic processes. The primary symptoms during adolescence include delayed sleep onset, sleep misperception, persistent negative thoughts about sleep, and physiological hyperarousal-paralleling features observed in adult insomnia. An approach centered on distinct presentations may provide a framework for precision-based treatment options. Enhanced comprehension of insomnia's manifestations across diverse developmental stages can facilitate accurate assessment. Efforts to subtype insomnia in childhood align with this objective, potentially guiding the selection of appropriate treatments tailored to individual neurobiological, clinical, and familial features.

Response to iron supplementation is similar between boys and girls with pediatric sleep movement disorders.

OBJECTIVES: This study aims to investigate sex differences in response to iron supplementation in children and adolescents suffering from sleep-related movement disorders such as Restless Legs Syndrome (RLS), Periodic Limb Movement Disorder (PLMD), and Restless Sleep Disorder (RSD). METHODS: Data were retrieved and reanalyzed from previous studies involving children with RLS, PLMD, or RSD. The analysis included 54 patients treated with intravenous (IV) ferric carboxymaltose (FCM) and 31 patients treated with oral ferrous sulfate (FS). Demographic, biological, and clinical parameters were compared between sexes. Clinical outcomes were measured using the Clinical Global Impression rating scales for severity (CGI-S) and improvement (CGI-I). RESULTS: In the group treated with IV FCM, no significant differences were found between males and females in demographic (age), biological (ferritin, iron, total iron-binding capacity, transferrin), or clinical parameters (CGI-S and CGI-I). However, among adolescents, females showed significantly better clinical improvement (CGI-I) compared to males (t-value 2.428, p < 0.024). In the group treated with oral FS, no significant sex differences were observed in any parameters. Side effects were reported by a small number of patients, with no significant difference between sexes. CONCLUSION: The findings indicate no major significant sex-based differences in response to iron supplementation for treating sleep-related movement disorders in children and adolescents, despite distinct hormonal and physiological differences in iron metabolism. Both boys and girls benefit similarly from iron treatment during this developmental stage, suggesting that a standardized approach to iron supplementation may be effective. However, individual assessment and monitoring remain crucial to ensure optimal outcomes.

Sleep and follow-up characteristics of Hispanic patients: Insights from a comparative analysis with White patients in polysomnographic split-night studies.

BACKGROUND: Limited attention has been given to exploring the efficacy of titration in split-night polysomnography (PSG) and the factors influencing adherence to continuous positive airway pressure (CPAP) therapy. This study aims to evaluate the severity of OSA and PSG parameters in HP compared to WP. METHODS: Split-night PSG studies conducted on adults. Participants were categorized based on self-reported ethnicity as either HP or WP. RESULTS: The study enrolled 50 WP (15 women, 35 men, mean age 60.5 ± 13.60 years, mean BMI 34.2 ± 7.48) and 45 HP (24 women, 21 men, mean age 54.9 ± 13.06 years, mean BMI 37.3 ± 7.88). HP exhibited a mean apnea-hypopnea index (AHI) of 51.1 ± 33.67, saturation nadir of 77.8 ± 10.19, and time spent with saturation <90% of 21.0 ± 26.93 min. In WP, the mean AHI was 39.2 ± 24.49, saturation nadir 81.6 ± 9.04, and time spent <90% was 10.4 ± 17.17 min. All observed differences were statistically significant (p < 0.05). Auto CPAP was prescribed to all patients, with adherence at 3-4 months being 75% ± 30 for HP, with a usage of 5.5 ± 2.2 h, and a residual AHI of 3 ± 3.5. In WP, adherence was 79% ± 30, usage was 5.9 ± 2.1 h, and residual AHI was 3.6 ± 6.2. None of these differences reached statistical significance. Among HP, 37% missed follow-up appointments compared to 12% of WP. More HP used full-face masks, while more WP preferred nasal masks. CONCLUSIONS: HP exhibited significantly worse OSA parameters during the diagnostic phase of PSG compared to WP. HP had a significantly higher no-show percentage than WP. CPAP adherence and residual AHI were not statistically different, but more HP missed follow-up appointments than WP.

Changes in time structure of periodic leg movements during sleep in restless legs syndrome: Effects of sex and age.

BACKGROUND: The objective of this study was to check the hypothesis that in women with restless legs syndrome (RLS) different changes occur in periodic leg movements during sleep (PLMS) during the post-menopausal period (using >50 years as a proxy) than in men of the same age. METHODS: We recruited 36 untreated patients aged 18-50 years (19 men, median age 40 years, and 17 women, median age 37 years) while the remaining 67 were >50 years old (24 men, median age 66.6 years, and 43 women, median age 60.0 years). Leg movement activity during sleep was analyzed by means of an approach utilizing indexes especially suitable to assess leg movement periodicity. RESULTS: No significant difference was seen between men in the two age groups; conversely, in women, a clear and significant increase in Periodicity Index was observed in the older group, along with a decrease in isolated leg movements. In women, a clear age-related enhancement of PLMS was found in the intermovement interval graphs, especially in the 16-22 s range, which was more evident than that observed in men. The results remained unchanged also when they were replicated by selecting only subjects aged 18-45 years vs. those aged >55 years. CONCLUSIONS: Our findings indicate that assessing PLMS in women after menopause is clinically relevant because they are probably connected with the hormonal fluctuations of this period of life. Translationally, identifying and addressing PLMS in post-menopausal women is crucial for optimizing their sleep health and addressing potential health risks associated with sleep disturbances.

Polysomnographic features associated with clonazepam and melatonin treatment in isolated REM sleep behavior disorder: Time for new therapeutic approaches?

AIMS: Although clonazepam (CLO) and melatonin (MLT) are the most frequently used treatments for REM sleep behavior disorder, the polysomnographic features associated with their use are little known. The aim of this study was to evaluate polysomnographic and clinical parameters of patients with idiopathic/isolated REM sleep behavior disorder (iRBD) treated chronically with CLO, sustained-release MLT, alone or in combination, and in a group of drug-free iRBD patients. METHODS: A total of 96 patients were enrolled: 43 drug-free, 21 with CLO (0.5-2 mg), 20 with sustained-release MLT (1-4 mg), and 12 taking a combination of them (same doses). Clinical variables and polysomnography were collected. RESULTS: Although clinical improvement was reported in all groups, MLT impacted sleep architecture more than the other treatments, with significant and large increase in N3 stage, moderate reduction in N2 and REM sleep, and moderate increase in REM latency. CLO moderately increased the percentage of both REM sleep and especially N2, while reducing N1 and wakefulness. Patients treated with both CLO and MLT did not show major changes in sleep architecture. CONCLUSION: These results suggest that the administration of MLT or CLO impacts (positively) on sleep parameters of iRBD patients. However, there is a need to better stratify patients, in order to treat them in a targeted manner, depending on the patient's individual sleep architecture and expected differential effects of these agents.

Polysomnographically Defined Restless Sleep Disorder and Periodic Limb Movements during Sleep in Children Born Prematurely.

INTRODUCTION: Children born prematurely (<37 weeks' gestation) are at increased risk of perinatal complications, comorbidities, and iron deficiency. Iron deficiency is associated with restless legs syndrome and periodic limb movement disorder. In this study, we assessed the prevalence of restless sleep disorder (RSD) and elevated periodic limb movements during sleep (PLMS) in children born prematurely who underwent polysomnography. METHODS: A retrospective chart review of sleep studies was conducted in children aged 1-18 years (median age 4 years) with a history of premature birth. Children with genetic syndrome, airway surgery, or tracheostomy were excluded. Three groups were compared: children with PLMS index >5, children with RSD, and children with neither elevated PLMS index nor RSD. RESULTS: During the study, 2577 sleep studies were reviewed. Ninety-two studies fit our criteria and were included in the analysis. The median age at birth was 31 weeks, and the interquartile range (IQR) was 27-34 weeks. A total of 32 (34.8%) children were referred for restless sleep and 55 (59.8%) for snoring. After polysomnography, 18% were found to have a PLMS index >5/h, and 14% fit the criteria for restless sleep disorder (RSD). There were no statistically significant differences in PSG parameters among the children with RSD, PLMS, and the remaining group, except for lower obstructive apnea/hypopnea index (Kruskal-Wallis ANOVA 8.621, p = 0.0135) in the RSD group (median 0.7, IQR 0.3-0.9) than in the PLMS (median 1.7, IQR 0.7-3.5) or the non-RSD/non-PLMS (median 2.0, IQR 0.8-4.5) groups. CONCLUSIONS: There was an elevated frequency of RSD and elevated PLMS in our cohort of children born prematurely. Children born prematurely are at higher risk of iron deficiency which can be a contributor factor to sleep -related movement disorders. These results add new knowledge regarding the prevalence of RSD and PLMS in these children.

Sensory aspects of restless legs syndrome: Clinical, neurophysiological and neuroimaging prospectives.

Restless Legs Syndrome (RLS) is a complex sensorimotor disorder, classified among the sleep-related movement disorders. Although sensory symptoms appear as key features of the disorder, they are still poorly characterized from a clinical perspective and conceptualized from a pathophysiological point of view. In this review, we aim to describe the clinical and functional substrates of RLS, focusing mainly on its sensory symptoms and on their neurophysiological and anatomical correlates. Knowledge of both subjective sensory symptoms and objective sensory signs are still controversial. Current data also indicate that the sensory component of RLS seems to be subserved by anomalies of sensorimotor integration and by mechanism of central sensitization. Overall, electrophysiological findings highlight the involvement of multiple generators in the pathogenesis of RLS, eventually resulting in an increased nervous system excitability and/or alterations in inhibition within the somatosensory and nociceptive pathways. Structural and functional neuroimaging data show the involvement of several crucial areas and circuits, among which the thalamus appears to play a pivotal role. A holistic approach looking at brain connectivity, structural or functional abnormalities, and their interplay with molecular vulnerability and neurotransmitter alterations is warranted to disentangle the complex framework of RLS.

Large muscle group movements during sleep in restless leg syndrome: neurophysiological and clinical implications.

STUDY OBJECTIVES: Recently, criteria have been drawn up for large muscle group movements during sleep (LMM), defined as movements lasting for 3-45 seconds in adults, which are often accompanied by changes in sleep stage, arousals, and increases in heart rate. The aim of this study was to characterize LMM in restless legs syndrome (RLS) in order to better evaluate their impact on the neurophysiology of the disorder and, therefore, the possible clinical implications. METHODS: Consecutive, drug-free patients diagnosed with RLS and controls, aged 18 years or more, were retrospectively enrolled. Leg movement activity-short-interval (SILMS), periodic (PLMS), and isolated (ISOLMS) leg movements during sleep-and LMM were detected and scored. RESULTS: In total, 100 patients and 67 controls were recruited. All movement measures were significantly higher in RLS. A significant positive correlation was found between LMM and ISOLMS index but not PLMS index in both groups. LMM index showed a significant negative correlation with total sleep time, sleep efficiency, and percentage of sleep stages N3 and R, as well as a significant positive correlation with the number of awakenings, and percentage of sleep stages N1 and N2 only in patients with RLS. No significant correlation was found between either LMM or PLMS index and RLS severity. CONCLUSIONS: Different types of movements, including SILMS, ISOLMS, and LMM, play somewhat distinct roles in sleep neurophysiology in RLS. Notably, LMM, a newly recognized category of movements, demonstrates associations with sleep architecture instability and fragmentation, arousals, and awakenings, suggesting potential clinical implications.

Unveiling the pathophysiology of restless legs syndrome through transcriptome analysis.

The aim of this study was to analyze signaling pathways associated with differentially expressed messenger RNAs in people with restless legs syndrome (RLS). Seventeen RLS patients and 18 controls were enrolled. Coding RNA expression profiling of 12,857 gene transcripts by next-generation sequencing was performed. Enrichment analysis by pathfindR tool was carried-out, with p-adjusted ≤0.001 and fold-change ≥2.5. Nine main different network groups were significantly dysregulated in RLS: infections, inflammation, immunology, neurodegeneration, cancer, neurotransmission and biological, blood and metabolic mechanisms. Genetic predisposition plays a key role in RLS and evidence indicates its inflammatory nature; the high involvement of mainly neurotropic viruses and the TORCH complex might trigger inflammatory/immune reactions in genetically predisposed subjects and activate a series of biological pathways-especially IL-17, receptor potential channels, nuclear factor kappa-light-chain-enhancer of activated B cells, NOD-like receptor, mitogen-activated protein kinase, p53, mitophagy, and ferroptosis-involved in neurotransmitter mechanisms, synaptic plasticity, axon guidance, neurodegeneration, carcinogenesis, and metabolism.

Targeting the adenosinergic system in restless legs syndrome: A pilot, "proof-of-concept" placebo-controlled TMS-based protocol.

Restless Legs Syndrome (RLS) is a common sleep disorder characterized by an urge to move the legs that is responsive to movement (particularly during rest), periodic leg movements during sleep, and hyperarousal. Recent evidence suggests that the involvement of the adenosine system may establish a connection between dopamine and glutamate dysfunction in RLS. Transcranial magnetic stimulation (TMS) is a non-invasive electrophysiological technique widely applied to explore brain electrophysiology and neurochemistry under different experimental conditions. In this pilot study protocol, we aim to investigate the effects of dipyridamole (a well-known enhancer of adenosinergic transmission) and caffeine (an adenosine receptor antagonist) on measures of cortical excitation and inhibition in response to TMS in patients with primary RLS. Initially, we will assess cortical excitability using both single- and paired-pulse TMS in patients with RLS. Then, based on the measures obtained, we will explore the effects of dipyridamole and caffeine, in comparison to placebo, on various TMS parameters related to cortical excitation and inhibition. Finally, we will evaluate the psycho-cognitive performance of RLS patients to screen them for cognitive impairment and/or mood-behavioral dysfunction, thus aiming to correlate psycho-cognitive findings with TMS data. Overall, this study protocol will be the first to shed lights on the neurophysiological mechanisms of RLS involving the modulation of the adenosine system, thus potentially providing a foundation for innovative "pharmaco-TMS"-based treatments. The distinctive TMS profile observed in RLS holds indeed the potential utility for both diagnosis and treatment, as well as for patient monitoring. As such, it can be considered a target for both novel pharmacological (i.e., drug) and non-pharmacological (e.g., neuromodulatory), "TMS-guided", interventions.