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Sleep promotes the consolidation of newly acquired associative memories. Here we used neuronal oscillations in the human EEG to investigate sleep-dependent changes in the cortical memory trace. The retrieval activity for object-color associations was assessed immediately after encoding and after 3 hr of sleep or wakefulness. Sleep had beneficial effects on memory performance and led to reduced event-related theta and gamma power during the retrieval of associative memories. Furthermore, event-related alpha suppression was attenuated in the wake group for memorized and novel stimuli. There were no sleep-dependent changes in retrieval activity for missed items or items retrieved without color. Thus, the sleep-dependent reduction in theta and gamma oscillations was specific for the retrieval of associative memories. In line with theoretical accounts on sleep-dependent memory consolidation, decreased theta may indicate reduced mediotemporal activity because of a transfer of information into neocortical networks during sleep, whereas reduced parietal gamma may reflect effects of synaptic downscaling. Changes in alpha suppression in the wake group possibly index reduced attentional resources that may also contribute to a lower memory performance in this group. These findings indicate that the consolidation of associative memories during sleep is associated with profound changes in the cortical memory trace and relies on multiple neuronal processes working in concert.

Background During the last few years, technology support for various health-related areas is becoming increasingly common. Not only are nutrition apps or sports apps available, but apps regarding sleep are also available. As the prevalence of sleep disturbances in infancy and childhood is quite high, supportive strategies are necessary to help families to sleep healthy. Thus, this study addresses the topic of sleep apps for babies and children. Methods Sleep apps were searched using different strings. Age-oriented apps were scored using different criteria which were theoretically based (e.g., description, costs, downloads). Results We found 573 sleep apps using the Apple App Store and Google Play Store with the search strings “sleep” and “app” and “baby” or “children”. Of these, 15.4% were not declared for children or babies. Content of most apps was lullabies or music and songs. Sleep-related aspects as sleep information or sleep education was very rare. Conclusions There is a new field of sleep help—with sleep apps used by families. Because of the high prevalence concerning sleep problems, the market concerning sleep helping apps is well used. However, most of the sleep apps did not have declarations concerning age and other factors. Parents should be careful using sleep apps for their offspring.

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This study examined the role of sleep disturbances and insomnia in the context of stress reactivity in adolescence. One-hundred and thirty-five 11-18 year olds (M age = 14.2 years, SD = 1.9, 52% female) completed the Trier Social Stress Test for Children. Salivary cortisol and subjective stress ratings were collected at six time points, and heart rate as well as heart rate variability were measured pre-, during and post-stress induction. Additionally, sleep disturbances and insomnia diagnosis were assessed by a self-report questionnaire and a sleep interview. Robust mixed models investigated if adolescents with compared with adolescents without (a) sleep disturbances and (b) insomnia differ regarding cortisol, heart rate, heart rate variability and psychological stress reactivity considering gender effects. The results indicated that boys with high sleep disturbances showed higher cortisol activity compared with boys with low sleep disturbances, B = 0.88, p < 0.05. Moreover, in boys with insomnia, heart rate and alpha 1 significantly differ less than in boys without insomnia.These findings support the notion of sex differences regarding the association between poor sleep and increased activity of the hypothalamic-pituitary-adrenal axis, and a less adaptable autonomic nervous system in boys in response to an experimental social stress task.