LAUSR

Dear members of the ESRS, Dear readers of JSR, Let me welcome you to the third issue of JSR in 2023, which will be published in June this year. As always, this issue of JSR encompasses a broad overview of the most recent developments in sleep medicine and sleep research. For aspects of sleep medicine, this issue covers sleepdisordered breathing, insomnia, dreams and nightmares, rapid eye movement (REM) sleep behaviour disorder and restless legs syndrome. This issue also covers relationships between sleep and development, sleep and glucose regulation, and sleep and fatigue/ drowsiness. Let me highlight some of these articles for you. Ried et al. (2023) report the results from a study investigating the impact of medicinal cannabis on sleep in adults with insomnia. This randomised double-blind placebo-controlled crossover study investigated 29 participants with clinical insomnia who completed the crossover trial. Participants either received placebo or active oil containing 10 mg ml 1 tetrahydrocannabinol (THC) and 15 mg ml 1 cannabidiol (CBD) over 2 weeks followed by a 1-week washout period before crossover. The authors report that this medicinal cannabis oil was well tolerated and improved sleep, represented by 60% of participants no longer classified as clinical insomniacs at the end of the intervention period. In my opinion, these results are highly interesting, but still require replication in much larger samples before general recommendations concerning the use of medicinal cannabis for insomnia treatment can be given. Broström et al. (2023) conducted a systematic review and meta-analysis of the prevalence of restless legs syndrome (RLS) in the general adult population encompassing data from all over the world. The authors could include 97 studies with more than 480,000 participants from 33 different countries. It turned out that the overall pooled prevalence of RLS was 3%, depending on the methodological quality of studies included. It seemed that the corrected pooled prevalence for men was 2.8%, for women 4.7%, for alcohol consumers 1.4% and smokers 2.7%. The results also indicate that the prevalence was higher in developed versus developing countries, and among elderly patients versus younger patients. These data may serve well to plan healthcare for RLS. Another meta-analysis by Bezerra et al. (2023) looked at the effects of the use of hormonal contraceptives on sleep in women. In this analysis, 13 studies were identified that could be included in the final systematic review and meta-analysis. A substantial amount of studies considered data from polysomnography (PSG). The only statistically significant results between using contraceptives versus non-using were observed in respect of wake after sleep onset, which was 7 min shorter among contraceptive users. The authors come to the conclusion that hormonal contraceptives are not associated with clinically relevant changes in sleep patterns in women. Though this is more of a “negative” result, I guess it can be considered very important for users of hormonal contraception. Düren et al. (2023) report on an issue that has not been investigated too frequently in the past, i.e. interpersonal touch in relationship to subjective sleep quality. The authors used data from the Touch Test and a cross-sectional survey that was conducted in 2020. More than 15,000 adults from the UK were incorporated in this study with a mean age of 56 years. The authors collected a variety of data on hugs, strokes, massages, etc., and on sleep quality. It seems that affective touch before sleep was perceived to have positive effects on sleep. Interestingly, touch recency emerged as a significant predictor for some sleep variables. Experiencing too much touch in contrast was related to lower sleep quality and higher instances of waking up after sleep onset. These data are very interesting because they relate to typical human behaviours prior to sleep, which up to now have been understudied. Further research, also from a longitudinal perspective, is needed. Singh et al. (2023) report data from a study that investigated tonic REM sleep muscle activity in relationship to the phenoconversion risk to neurodegenerative disorder in isolated REM sleep behaviour disorder (RBD). The authors studied 64 patients with PSG-confirmed RBD, 19 who phenoconverted during follow-up. It turned out that phenoconverters in comparison to non-converters had significantly higher amounts of tonic REM sleep muscle activity during their baseline sleep study. The authors conclude that the percentage of tonic REM sleep without atonia was the strongest biomarker of phenoconversion in this cohort of patients. This constitutes an interesting data set, which might open perspectives for identifying very early those patients with RBD who are at an increased risk for phenoconversion.