Toddler's self-regulation strategies in a challenge context are nap-dependent

Sleep Moderates the Association Between Response Inhibition and Self-Regulation in Early Childhood

Early childhood is a time of rapid developmental changes in sleep, cognitive control processes, and the regulation of emotion and behavior. This experimental study examined sleep-dependent effects on response inhibition and self-regulation, as well as whether acute sleep restriction moderated the association between these processes. Preschool children (N = 19; 45.6 ± 2.2 months; 11 female) followed a strict sleep schedule for at least 3 days before each of 2 morning behavior assessments: baseline (habitual nap/night sleep) and sleep restriction (missed nap/delayed bedtime). Response inhibition was evaluated via a go/no-go task. Twelve self-regulation strategies were coded from videotapes of children while attempting an unsolvable puzzle. We then created composite variables representing adaptive and maladaptive self-regulation strategies. Although we found no sleep-dependent effects on response inhibition or self-regulation measures, linear mixed-effects regression showed that acute sleep restriction moderated the relationship between these processes. At baseline, children with better response inhibition were more likely to use adaptive self-regulation strategies (e.g., self-talk, alternate strategies), and those with poorer response inhibition showed increased use of maladaptive self-regulation strategies (e.g., perseveration, fidgeting); however, response inhibition was not related to self-regulation strategies following sleep restriction. Our results showing a sleep-dependent effect on the associations between response inhibition and self-regulation strategies indicate that adequate sleep facilitates synergy between processes supporting optimal social-emotional functioning in early childhood. Although replication studies are needed, findings suggest that sleep may alter connections between maturing emotional and cognitive systems, which have important implications for understanding risk for or resilience to developmental psychopathology.

Napping: A public health issue. From epidemiological to laboratory studies

Sleep specialists have proposed measures to counteract the negative short- and long-term consequences of sleep debt, and some have suggested the nap as a potential and powerful "public health tool". Here, we address this countermeasure aspect of napping viewed as an action against sleep deprivation rather than an action associated with poor health. We review the physiological functions that have been associated positively with napping in both public health and clinical settings (sleep-related accidents, work and school, and cardiovascular risk) and in laboratory-based studies with potential public health issues (cognitive performance, stress, immune function and pain sensitivity). We also discuss the circumstances in which napping-depending on several factors, including nap duration, frequency, and age-could be a potential public health tool and a countermeasure for sleep loss in terms of reducing accidents and cardiovascular events and improving sleep-restriction-sensitive working performance. However, the impact of napping and the nature of the sleep stage(s) involved still need to be evaluated, especially from the perspective of coping strategies in populations with chronic sleep debt, such as night and shift workers.

Napping reduces emotional attention bias during early childhood

Sleep loss alters processing of emotional stimuli in preschool-aged children. However, the mechanism by which sleep modifies emotional processing in early childhood is unknown. We tested the hypothesis that a nap, compared to an equivalent time spent awake, reduces biases in attention allocation to affective information. Children (n = 43; M = 55.40 months, SD = 8.05 months) completed a Dot Probe task, which provides a measure of attention biases to emotional stimuli, following a mid-day nap and an equivalent interval spent awake. No emotional attention biases emerged when children napped. However, when nap-deprived, children exhibited biases towards negative and positive stimuli. This emotional bias after wake was greater in children who napped habitually. Gender differences also emerged such that females were more attentive to positive emotional stimuli whereas males showed heightened attention to negative emotional stimuli, regardless of having napped or not. Moreover, greater slow wave activity (SWA) during the nap was associated with faster responding, which suggests that SWA may promote efficiency of attention allocation. A video abstract of this article can be viewed at: https://www.youtube.com/watch?v=JIoZ8mzxQgg.

Daily dynamics in sleep and behavior of young African-American children: A convoluted dyad?!

Prior research has provided evidence that in children sleep and behavior are related. We aimed to determine the association between naturalistic daily variations in sleep and behavioral functioning. African American children, 5.4±1.7years old, living on the south side of Chicago participated in a repeated measures study to assess this sleep-behavior link. Data was obtained from three separate two-week periods of 24-hour actigraphy and the parental version of the Behavioral Assessment System for Children. Canonical correlations analyses were applied to investigate the relation between individual changes in sleep and behavior. After 1-month, weekday average sleep duration primarily related to internalizing behaviors, while within-child variability of sleep related to behavioral changes which may involve internalizing and externalizing symptoms. Week-weekend differences in sleep associated with maladaptive social skills. Over a 6-week period, sleep onset latency and sleep offset latency related to behavioral symptoms and maladaptive skills. Over a period of 3-months, sleep associated with symptomatic behaviors while the adverse impact of within-child variability of sleep attenuated. Alternatively, the week-weekend differences in bedtime, wake-up time, wake after sleep onset and sleep onset latency in particular related to internalizing and externalizing behavior problems. Findings showed that poor sleep related to dysfunctional behaviors. While maladaptive at the beginning, they may develop into symptomatic behaviors with potentially internalizing characteristics. As time goes on, individual changes in sleep onset and offset might be important clinical markers of a chronic 'social dysregulation'. Continued sufficient and regular sleep may improve daytime and nighttime behavioral regulation in early childhood.

The Timing of the Circadian Clock and Sleep Differ between Napping and Non-Napping Toddlers

The timing of the internal circadian clock shows large inter-individual variability across the lifespan. Although the sleep-wakefulness pattern of most toddlers includes an afternoon nap, the association between napping and circadian phase in early childhood remains unexplored. This study examined differences in circadian phase and sleep between napping and non-napping toddlers. Data were collected on 20 toddlers (34.2±2.0 months; 12 females; 15 nappers). Children followed their habitual napping and non-napping sleep schedules (monitored with actigraphy) for 5 days before an in-home salivary dim light melatonin onset (DLMO) assessment. On average, napping children fell asleep during their nap opportunities on 3.6±1.2 of the 5 days before the DLMO assessment. For these napping children, melatonin onset time was 38 min later (p = 0.044; d = 0.93), actigraphically-estimated bedtime was 43 min later (p = 0.014; d = 1.24), sleep onset time was 59 min later (p = 0.006; d = 1.46), and sleep onset latency was 16 min longer (p = 0.030; d = 1.03) than those not napping. Midsleep and wake time did not differ by napping status. No difference was observed in the bedtime, sleep onset, or midsleep phase relationships with DLMO; however, the wake time phase difference was 47 min smaller for napping toddlers (p = 0.029; d = 1.23). On average, nappers had 69 min shorter nighttime sleep durations (p = 0.006; d = 1.47) and spent 49 min less time in bed (p = 0.019; d = 1.16) than non-nappers. Number of days napping was correlated with melatonin onset time (r = 0.49; p = 0.014). Our findings indicate that napping influences individual variability in melatonin onset time in early childhood. The delayed bedtimes of napping toddlers likely permits light exposure later in the evening, thereby delaying the timing of the clock and sleep. Whether the early developmental trajectory of circadian phase involves an advance associated with the decline in napping is a question necessitating longitudinal data as children transition from a biphasic to monophasic sleep-wakefulness pattern.