Cortical Thinning and Sleep Slow Wave Activity Reductions Mediate Age-Related Improvements in Cognition During Mid-Late Adolescence

The Role of Sleep for Age-Related Differences in Neurobehavioral Performance

This study investigated developmental changes from childhood to adulthood in neurobehavioral performance and sleep measures. While many studies have examined age-related changes between childhood and adolescence and from mid-to-late adulthood, young adulthood has been overlooked. The main aim of this study was to investigate the effects of sleep loss on developmental changes in neurobehavioral performance and sleepiness in a natural setting. A total of 119 children, adolescents, and young adults (38 children aged 6-9; 38 adolescents aged 13-19; and 43 young adults aged 20-27) wore an actigraph for a continuous five-weekday night. Subjective sleepiness (Karolinska Sleepiness Scale) and neurobehavioral performance (using the psychomotor vigilance test and the digit symbol substitution test) were measured on five school days. The results showed that adolescents and young adults outperformed children on both the digit symbol substitution test and the psychomotor vigilance test measures. However, adolescents committed more errors of commission on the psychomotor vigilance test and reported higher levels of subjective sleepiness. The results are discussed in relation to brain maturation in various cognitive functions.

Parasomnias manifest different phenotypes of sleep-related behaviors in age and sex groups. A YouTube-based video research highlighting the age slope of sleepwalking

STUDY OBJECTIVE

Finding typical patterns - phenotypes - of sleep behaviors characterizing parasomnias in different age and sex groups.

METHODS

We analyzed YouTube videos on sleep-related behaviors likely representing parasomnias. We applied the search terms "sleepwalking", "somnambulism", "sleep eating", "sleep sex", "sleep talking", and "aggression in sleep" in six languages. We classified those persons shown on the videos into estimated biological sex and age (child, adult, elderly) groups. We scored the activity types by a self-made scale and applied binary logistic regression to analyze the association between sleep behaviors versus sex and age groups by the STATA package, providing a 95% confidence interval and the probability of statistical significance.

RESULTS

224 videos (102 women, 68 children, 16 adults, and 40 elderly people) were scored. Elderly people had significantly (P < 0.012) lower odds of sleepwalking compared to adults and children. Adult females performed complex manual activities during sleepwalking more often than males (P < 0.012). Elderly males had 40-fold odds compared to adults and children, to perform aggressive movements and 70-fold odds of complex movements in bed, compared to adults. Elderly people presented emotional behaviors less frequently than adults (P < 0.004), and females showed them twice as often as males. Adults sleep-talked full sentences more often than children and elderly people (P < 0.001).

CONCLUSION

Our results support the existence of age- and sex-specific parasomnia phenotypes, denoting possible safety measures. The remarkably low odds of sleepwalking in the elderly highlight the possibility of different pathomechanisms in higher age groups compared to children.

BRIEF SUMMARY AND STUDY IMPACT

Parasomnias present highly variable clinical forms and often cause injuries. Identifying typical phenotypes may help risk management and imply theoretical conclusions. Our study supports the existence of age-specific parasomnia phenotypes. We found that adult women have a high risk of performing dangerous activities during sleep, and elderly males often move violently in bed, likely representing dream enactment behaviors. Elderly people of both sexes have low odds of sleep ambulation- likely representing somnambulism; compared to adults and children, constituting a descending "age slope" of somnambulism that might reflect different underlying pathomechanisms in children versus adults and the elderly.

Associations between Sleep, Depression, and Cognitive Performance in Adolescence

The relevance of cognitive performance during adolescence requires further studies that analyze potential associated factors. This study aimed to analyze inductive reasoning, reading comprehension, and mathematical thinking (problem-solving and number and calculation) in relation to sleep and depression in 244 students aged 12-17 years (47.6% boys and 52.4% girls). Daytime sleepiness, sleep quality, dysthymia, and euthymia (state and trait) were assessed by self-reported questionnaires. Moreover, correlations between these variables and cognitive performance, and differences depending on sociodemographic variables (sex, age, or academic year) were analyzed using non-parametric tests. Robust regression models were also conducted to evaluate the predictive role of significant variables on cognitive performance. The results showed significant bidirectional relationships between sleep- and depression-related variables, and between the latter ones and cognitive performance. Depression-trait was more related to cognitive performance than depression-state, and euthymia more than dysthymia, but neither daytime sleepiness nor sleep quality significantly correlated with it. As for sociodemographic variables, girls reported worse sleep and more depressive symptoms than boys did, and younger students reported better sleep but performed worse than the older ones. Although these findings should be further explored in forthcoming studies adding other promising variables, they highlight the importance of promoting euthymia to improve cognitive performance in adolescents.