Epidemiology of sleep disorders, sleep deprivation, dreaming and spindles in sleep

Clinical and instrumental features in 82 patients with insufficient sleep syndrome

Insufficient sleep syndrome possibly represents the worldwide leading cause of daytime sleepiness, but remains poorly recognised and studied. The aim of this case series is to comprehensively describe a cohort of patients with insufficient sleep syndrome. Eighty-two patients were studied concerning demographic and socio-economic features, medical, psychiatric and sleep comorbidities, substance use, sleep symptoms, actigraphy, video-polysomnography, multiple sleep latency tests and treatment. The typical patient with insufficient sleep syndrome is a middle-aged adult (with no difference of gender), employed, who has a family, often carrying psychiatric and neurological comorbidities, in particular headache, anxiety and depression. Other sleep disorders, especially mild sleep apnea and bruxism, were common as well. Actigraphy was a valuable tool in the characterisation of insufficient sleep syndrome, showing a sleep restriction during weekdays, associated with a recovery rebound of night sleep during weekends and a high amount of daytime sleep. An over- or underestimation of sleeping was common, concerning both the duration of night sleep and daytime napping. The average daily sleep considering both daytime and night-time, weekdays and weekends corresponds to the recommended minimal normal duration, meaning that the burden of insufficient sleep syndrome could mainly depend on sleep fragmentation and low quality. Sleep efficiency was elevated both in actigraphy and video-polysomnography. Multiple sleep latency tests evidenced a tendency toward sleep-onset rapid eye movement periods. Our study offers a comprehensive characterisation of patients with insufficient sleep syndrome, and clarifies their sleeping pattern, opening avenues for management and treatment of the disorder. Current options seem not adapted, and in our opinion a cognitive-behavioural psychotherapy protocol should be developed.

Effects of polyphenol-rich interventions on sleep disorders: A systematic review and meta-analysis

Epidemiology studies have indicated that polyphenol consumption was more likely to have higher sleep quality, but some results remain controversial. A general overview of polyphenol-rich interventions on sleep disorders still lacks in the existing literature. Eligible randomized controlled trials (RCT's) literature retrieval was performed in six databases. Sleep efficiency, sleep onset latency, total sleep time, and PSQI were included as objective measures to compare the effects of placebo and polyphenols in patients with sleep disorders. Subgroup-analyses were performed based on treatment duration, geographic location, study design, and sample size. The mean differences (MD) with 95% confidence intervals (CI) were adopted for four continuous variable data of outcomes in pooled analysis. This study is registered on PROSPERO, number CRD42021271775. In total, 10 studies of 334 individuals were included. Pooled data demonstrated that administration of polyphenols decreases sleep onset latency (MD, -4.38 min; 95% CI, -6.66 to -2.11; P = 0.0002) and increases total sleep time (MD, 13.14 min; 95% CI, 7.54 to 18.74; P＜0.00001), whereas they have no effect on sleep efficiency (MD, 1.04; 95% CI, -0.32 to 2.41; P = 0.13) and PSQI (MD, -2.17; 95% CI, -5.62 to 1.29; P = 0.22). Subgroup analyses further indicated that treatment duration, study design, and number of participants appeared to be responsible for the largest proportion of accountable heterogeneity. Polyphenols' potential importance is highlighted by these findings in treating sleep disorders. The development of large-scale, randomized, controlled trials is recommended to providing further evidence for therapeutic use of polyphenols in a variety of sleep difficulties.

Assessment of the Psychometric Properties of the Holland Sleep Disorders Questionnaire in the Iranian Population

Background

Assessing sleep disorders and understanding their causes are essential for the proper treatment and management of the disorders. The Holland Sleep Disorders Questionnaire (HSDQ) is a self-assessment questionnaire that measures sleep problems and symptoms based on the six categories of sleep disorders described in the International Classification of Sleep Disorders-2 (ICSD-2). The aim of this study was at validating and assessing the psychometric properties of the HSDQ in Iranian adults.

Method

The study was carried out as a methodological and validation work. The guidelines for translation and cultural adaptation of patient-reported outcome measures were followed for the translation and the cultural validation of the tool. To examine construct validity, exploratory factor analysis (EFA) with 216 participants and confirmatory factor analysis (CFA) with 355 participants were used. As to the reliability, the test-retest method and, as to internal consistency, Cronbach's alpha were employed. Data analyses were done in SPSS-25 and LISREL-8.

Results

The CFA and EFA results confirmed the tool with six factors and 31 items. The R² index of the model was 0.99, which indicated that 99% of changes in the dependent variable (adults' sleep problem) were attributed to the independent variable (the 31 items). In other words, 0.99 of the changes in the dependent variable were due to the independent variables. The main indices of CFA (χ²/DF = 2.65, CFI = 0.91NNFI/TLI = 0.92GFI = 0.81, REMSEA = 0.043, R² = 0.99) were acceptable. In addition, a correlation coefficient below 0.05 was considered as significant. Reliability of the tool based on internal correlation (Cronbach's alpha) was in the 0.701–0.924 range for the subscales and equal to 0.789 for the whole tool.

Conclusion

In general, the results showed that the Farsi version of HSDQ (six factors and 31 items) had acceptable and applicable indices and it can be used as a valid tool in the Iranian society. The tool can be used as a reliable tool in different fields of medical sciences.

Effects of Sleep Deprivation on the Tryptophan Metabolism

Sleep has a regulatory role in maintaining metabolic homeostasis and cellular functions. Inadequate sleep time and sleep disorders have become more prevalent in the modern lifestyle. Fragmentation of sleep pattern alters critical intracellular second messengers and neurotransmitters which have key functions in brain development and behavioral functions. Tryptophan metabolism has also been found to get altered in SD and it is linked to various neurodegenerative diseases. The kynurenine pathway is a major regulator of the immune response. Adequate sleep alleviates neuroinflammation and facilitates the cellular clearance of metabolic toxins produced within the brain, while sleep deprivation activates the enzymatic degradation of tryptophan via the kynurenine pathway, which results in an increased accumulation of neurotoxic metabolites. SD causes increased production and accumulation of kynurenic acid in various regions of the brain. Higher levels of kynurenic acid have been found to trigger apoptosis, leads to cognitive decline, and inhibit neurogenesis. This review aims to link the impact of sleep deprivation on tryptophan metabolism and associated complication in the brain.