Sleep and its relation to cognition and behaviour in preschool‐aged children of the general population: a systematic review

This is the first systematic review of the literature on sleep and its relation to cognition and behaviour in preschool‐aged children. In comparison with the literature focused on school‐aged children, knowledge involving preschoolers is rather sparse. A total of 26 studies was included in this review, which revealed a high degree of heterogeneity regarding the type and means of measuring sleep variables and behavioural and cognitive variables, as well as the statistical methods employed. Amongst the 13 articles with the largest sample sizes (top 50% of the included studies, 12 different populations), 12 found that a higher quantity or quality of sleep was associated with better behavioural and/or cognitive outcomes. Results point to an association between sleep, behaviour and cognition as early as preschool years, but the strengths of associations reported in the articles were relatively small. Studies with a smaller sample size were less concordant. It is consistent with our findings that the strengths of association are small, and thus require large sample sizes to ensure statistical detection power. Different aspects of sleep were not associated with all cognitive or behavioural features in the same way, which underscores the need for specific measures rather than general ones such as ‘sleep problems’ or ‘behaviour problems’ to be able to decipher the relationships. There is also a need for large longitudinal studies using objective measures and accounting for confounding factors. The child's genotype has recently been shown to have a moderating role in the association between sleep and behaviour, and should be further explored.     

The use of actigraphy for assessment of the development of sleep/wake patterns in infants during the first 12 months of life

Maturation of sleep/wake patterns is one of the most important physiological developments during the first year of life. In this study, we aimed to compare the use of actigraphy and parental sleep diaries (SD) for recording the development of sleep/wake patterns longitudinally in term infants in their own home environments over the first 12 months of life. Twenty healthy term infants (7F/13M) were studied for 3 days each month in their own homes over the first 12 months of life. Sleep/wake patterns were recorded using both SD and actigraphy (AW) (AW64, Mini Mitter Co. Inc., Sunriver, OR, USA). The development of sleep and wake was analysed over 24 h, during the day (08:00-20:00 hours) and during the night (20:00-08:00 hours). A total of 186 studies had complete data sets for both analysis methods. Overall, there was no difference between methods of measurement for determination of the total percentage of sleep or wake over 24 h, or for the total percentage of sleep or wake during the day. However, at night, AW scored less time asleep (73.3 +/- 0.9%) and more time awake (26.7 +/- 0.9%) compared with the SD (80.7 +/- 1.04% and 19 +/- 1.0%, respectively, P < 0.001). Mean percentage sleep during the day decreased from 51% at 1 month to 28% at 12 months with the 1-month values being significantly higher than all other ages, while mean percentage sleep at night was only different between 1 month and 11 and 12 months. In conclusion actigraphy provides a useful tool for assessing the development infant sleep.     

The interplay between daily affect and sleep: a 2‐week study of young women

Little attention has been paid to the relation between daily affect and sleep, as most prior studies have focused instead on the role of pathological mood in the context of sleep disturbance. However, understanding the transaction between normal variations in emotional experiences and sleep can shed light on the premorbid vulnerabilities that trigger the evolution of affect and sleep into more problematic states. The present study used a 2‐week daily sampling approach to examine the impact of day‐to‐day variations in positive and negative affect on nightly self‐reported sleep‐onset latency, sleep duration and sleep quality in a sample of young women. Hierarchical linear modelling revealed temporal relations between positive and negative affect states and sleep parameters. Specifically, different aspects of both positive and negative affect were uniquely predictive of sleep indices, with sadness and serenity acting as the most consistent predictors. Additionally, better sleep quality was predictive of greater happiness the following day. These results highlight the importance of how our daily emotional experiences influence our nightly sleep and, in turn, how our sleep has an impact on our daily affect. Moreover, our findings may offer insight into the progression of normative levels of affect and sleep as they develop into comorbid depression, anxiety and insomnia.     

Mapping changes in cortical activity during sleep in the first 4 years of life

A coherent body of evidence supports the notion that sleep is a local and use‐dependent process. Significant changes in brain morphology and function occur in the first years of life, revealing a postero–anterior trajectory of cortical maturation. On this basis, a recent study demonstrated that regional cortical maturation between early childhood and late adolescence is reflected in regional changes of sleep slow wave activity (SWA) during non‐rapid eye movement (NREM) sleep. Our hypothesis is that changes of electroencephalogram (EEG) rhythms during sleep from birth to childhood are also mirrored by parallel regional changes in the EEG rhythms of sleep according to the assumption of a postero–anterior gradient in cortical maturation. We studied all‐night EEG of 39 healthy, full‐term, infants and children aged between 0 and 48 months, evaluating regional differences in NREM sleep. We confirmed the strictly local nature of sleep with frequency‐specific regional differences. Specifically, we found a general shift of maxima of the upper alpha activity from occipital to prefrontal regions, expressed mainly by the ~11 Hz frequency. This shift corresponds to a postero–anterior trajectory of the so‐called ‘slow spindles’. The theta and alpha EEG activity of the frontal cortex exhibits a clear, positive, correlation with age. We conclude that specific local differences during NREM sleep, parallel cortical maturation also in the first 4 years of life.     

Validity,potential clinical utility and comparison of a consumer activity tracker and a research‐grade activity tracker in insomnia disorder II: Outside the laboratory

Accurate assessment of sleep can be fundamental for monitoring, managing and evaluating treatment outcomes within diseases. A proliferation of consumer activity trackers gives easy access to objective sleep. We evaluated the performance of a commercial device (Fitbit Alta HR) relative to a research‐grade actigraph (Actiwatch Spectrum Pro) in measuring sleep before and after a cognitive behavioural intervention in insomnia disorder. Twenty‐five individuals with DSM‐5 insomnia disorder (M = 50.6 ± 15.9 years) wore Fitbit and Actiwatch and completed a sleep diary during an in‐laboratory polysomnogram, and for 1 week preceding and following seven weekly sessions of cognitive‐behavioural intervention for insomnia. Device performance was compared for sleep outcomes (total sleep time, sleep latency, sleep efficiency and wake after sleep onset). The analyses assessed (a) agreement between devices across days and pre‐ to post‐treatment, and (b) whether pre‐ to post‐treatment changes in sleep assessed by devices correlated with clinical measures of change. Devices generally did not significantly differ from each other on sleep variable estimates, either night to night, in response to sleep manipulation (pre‐ to post‐treatment) or in response to changes in environment (in the laboratory versus at home). Change in sleep measures across time from each device showed some correlation with common clinical measures of change in insomnia, but not insomnia diagnosis as a categorical variable. Overall, the Fitbit provides similar estimates of sleep outside the laboratory to a research grade actigraph. Despite the similarity between Fitbit and Actiwatch performance, the use of consumer technology is still in its infancy and caution should be taken in its interpretation.     

Sequence analysis of leg movements during sleep with different intervals (<10, 10–90 and >90 s) in restless legs syndrome

The aim of this study was to define the time structure of leg movements during sleep occurring with an intermovement interval (onset‐to‐onset) shorter than 10 s in patients with restless legs syndrome and controls, and to compare it to the structure of movements with intervals of 10–90 s or >90 s. Polysomnographic recordings of 141 untreated patients and 68 age‐matched normal controls were analysed. All movements were detected and classified into three categories, separated by intervals of <10, 10–90 or >90 s. The number of movements included in each category was significantly higher in patients than in controls. The movements with an interval of >90 s occurred steadily during the night, whereas the hourly distribution of movements with intervals of <10 or 10–90 s was decreasing or bell‐shaped in patients or controls, respectively. Movements with an interval of <10 s tended to have a shorter duration and constituted shorter sequences than movements with intervals of 10–90 or >90 s. The time structure features of the three categories of movements considered in this study were found to be clearly different. This, together with previous observations on the differential effects of dopamine agonists on movements with different intervals, suggests that movements with intervals of <10 and >90 s are regulated by neurotransmitter mechanisms different from those modulating movements with an interval of 10–90 s.     

The daily variation in sleepiness and its relation to the preceding sleep episode—a prospective study across 42 days of normal living

Sleepiness is linked to accidents and reduced performance, and is usually attributed to short/poor prior sleep and sleepiness. However, while the link between reduced sleep and subsequent sleepiness is well established in laboratory experiments of sleep reduction, very little is known about the day‐to‐day variation of sleepiness in everyday life and its relation to the immediately preceding sleep episode. The purpose of the present study was to investigate the characteristics of this relation across 42 consecutive days. Fifty volunteers participated. Self‐reports of sleep were given in the morning and recorded with actigraphy; health was rated in the evening; and sleepiness was rated at eight points during the day (on a scale of 1–9). Results from mixed‐model regression analyses showed that, on average, total sleep time predicted sleepiness during the rest of the day across the 42 days, with sleepiness increasing with shorter preceding sleep (β = ?0.15 units h^?1, P < 0.001). Sleepiness also increased with earlier time of rising and lower‐rated sleep quality. Days off reduced sleepiness, but was accounted for by sleep. Self‐rated health improved when sleepiness was low during the same day (β = ?0.36 unit unit^?1 of rated health, P < 0.001), but the two were measured simultaneously. Napping was related to high sleepiness during the same day. Actigraphy measures of sleep duration showed similar, but somewhat weaker, effects than diary measures. It was concluded that the main determinants of daytime sleepiness in a real‐life day‐to‐day context were short sleep, poor sleep and early rising, and that days with high sleepiness ended with ratings of poorer health.     

Contracting COVID-19 in the first and second trimester of pregnancy: what we know – a concise qualitative systematic review

IntroductionRecent medical literature has drawn attention to the possible influence of COVID-19 on the course of pregnancies. As the coherence of results seems to vary, especially in relation to first and second trimester pregnancies, a concise qualitative systematic review can shed light on the most recent data.Material and methodsA structured systematic search was performed to collect all COVID-19 pregnancy-related articles published between January 1 and September 16, 2020. Two independent reviewers evaluated studies using the STROBE statement in combination with the CERQual quality assessment of findings.ResultsIn total 1387 articles were screened and finally 22 studies were evaluated (179 1^st/2^nd trimesters of pregnant women with COVID-19). The majority of reported mothers who contracted COVID-19 during 1^st/2^nd trimesters are yet to complete their pregnancy.ConclusionsEvidently a limited amount of data is available. Usually, mothers and newborns are discharged from the hospital without any serious complications. Further observations are imperative.     

Prevalence of human papillomavirus in women attending cervical screening in the UK and Ireland: New data from northern Ireland and a systematic review and meta‐analysis

There is substantial international variation in human papillomavirus (HPV) prevalence; this study details the first report from Northern Ireland and additionally provides a systematic review and meta‐analysis pooling the prevalence of high‐risk (HR‐HPV) subtypes among women with normal cytology in the UK and Ireland. Between February and December 2009, routine liquid based cytology (LBC) samples were collected for HPV detection (Roche Cobas® 4800 [PCR]) among unselected women attending for cervical cytology testing. Four electronic databases, including MEDLINE, were then searched from their inception till April 2011. A random effects meta‐analysis was used to calculate a pooled HR‐HPV prevalence and associated 95% confidence intervals (CI). 5,712 women, mean age 39 years (±SD 11.9 years; range 20–64 years), were included in the analysis, of which 5,068 (88.7%), 417 (7.3%) and 72 (1.3%) had normal, low, and high‐grade cytological findings, respectively. Crude HR‐HPV prevalence was 13.2% (95% CI, 12.7–13.7) among women with normal cytology and increased with cytological grade. In meta‐analysis the pooled HR‐HPV prevalence among those with normal cytology was 0.12 (95% CIs, 0.10–0.14; 21 studies) with the highest prevalence in younger women. HPV 16 and HPV 18 specific estimates were 0.03 (95% CI, 0.02–0.05) and 0.01 (95% CI, 0.01–0.02), respectively. The findings of this Northern Ireland study and meta‐analysis verify the prevalent nature of HPV infection among younger women. Reporting of the type‐specific prevalence of HPV infection is relevant for evaluating the impact of future HPV immunization initiatives, particularly against HR‐HPV types other than HPV 16 and 18. J. Med. Virol. 85:295–308, 2013. © 2012 Wiley Periodicals, Inc.     

The genetic profile of dysferlinopathy in a cohort of 209 cases: Genotype–phenotype relationship and a hotspot on the inner DysF domain

Dysferlinopathy is a group of autosomal recessive muscular dystrophies caused by variants in the dysferlin gene (DYSF), with variable proximal and distal muscle involvement. We performed DYSF gene analyses of 200 cases suspected of having dysferlinopathy (Cohort 1), and identified diagnostic variants in 129/200 cases, including 19 novel variants. To achieve a comprehensive genetic profile of dysferlinopathy, we analyzed the variant data from 209 affected cases from unrelated 209 families, including 80 previously diagnosed and 129 newly diagnosed cases (Cohort 2). Among the 90 types of variants identified in 209 cases, the NM_003494.3: c.2997G>T; p.Trp999Cys, was the most frequent (96/420; 22.9%), followed by c.1566C>G; p.Tyr522* (45/420; 10.7%) on an allele base. p.Trp999Cys was found in 70/209 cases (33.5%), including 20/104 cases (19.2%) with the Miyoshi muscular phenotype and 43/82 cases (52.4%) with the limb‐girdle phenotype. In the analysis of missense variants, p.Trp992Arg, p.Trp999Arg, p.Trp999Cys, p.Ser1000Phe, p.Arg1040Trp, and p.Arg1046His were located in the inner DysF domain, representing in 113/160 missense variants (70.6%). This large cohort highlighted the frequent missense variants located in the inner DysF domain as a hotspot for missense variants among our cohort of 209 cases (>95%, Japanese) and hinted at their potential as targets for future therapeutic strategies.