Altered brain activity related to inhibitory processing in youth with insomnia.

Insomnia has been shown to negatively affect one's cognitive functioning. While there has been some evidence suggesting sleep disruption in relation to impaired inhibitory control, a major component of executive function, little is known about the underlying neural processing in insomnia. The current study aimed to examine the differences in the behavioral responses and electroencephalography (EEG) correlates of inhibitory control between youths with insomnia and healthy sleepers. Twenty-eight participants with insomnia disorder and 31 healthy sleeper controls aged between 15 and 25 completed the study. Electroencephalographic activity was recorded during the Cued Go/NoGo (CGNG) task, a task assessing inhibitory control. Although insomnia group exhibited comparable behavioral performance to the healthy sleeper group, they showed impaired attention preparation, as displayed by a smaller contingent negative variation (CNV) component (F = 4.10, p = 0.048) after cue onset; and demonstrated impaired inhibitory control, as evidenced by smaller N2 and theta power on 200-350 ms (MANCOVA multivariate Group effect, F = 5.85, p < 0.001). The results suggested that youths with insomnia demonstrated altered brain activity during inhibitory control, despite their comparable behavioral performance. Given that impaired inhibitory control is often implicated in psychopathology, future studies with a longitudinal design are needed to further explore the long-term impacts and trajectory of altered inhibitory control in youths with insomnia.

Effects of insomnia symptoms and objective short sleep duration on memory performance in youths.

Sleep quantity and quality are both important for optimal development and functioning during youth. Yet few studies have examined the effects of insomnia symptoms and objective short sleep duration on memory performance among adolescents and young adults. One-hundred and ninety participants (female: 61.6%) aged from 12 to 24 years completed this study. All participants underwent a clinical interview, a 7-day actigraphic assessment, a battery of self-report questionnaires and cognitive tests to assess working memory and episodic memory. Insomnia symptoms were defined as a score ≥ 9 on the Insomnia Severity Index, and objective short sleep duration was defined as average total sleep time less than 7 hr for those aged 12-17 years, and 6 hr for those aged 18 years and above as assessed by actigraphy. Insomnia symptoms were significantly associated with worse self-perceived memory (p < .05) and poorer performance on the digit span task (p < .01), but not the dual N-back task and verbal learning task. There was no significant difference in any of the memory measures between participants with objective short sleep duration and their counterparts. No interaction effect was found between insomnia and short sleep duration on any of the objective memory outcomes. Insomnia symptoms, but not objective short sleep duration, were associated with poorer subjective memory and objective working memory performance in youths. Further studies are needed to investigate the underlying mechanisms linking insomnia and memory impairments, and to delineate the long-term impacts of insomnia on other aspects of neurocognitive functioning in youth.

Neural response to rewards in youths with insomnia.

STUDY OBJECTIVES: Insomnia and depression are common comorbid conditions in youths. Emerging evidence suggests that disrupted reward processing may be implicated in the association between insomnia and the increased risk for depression. Reduced reward positivity (RewP) as measured by event-related potential (ERP) has been linked to depression, but has not been tested in youths with insomnia. METHODS: Twenty-eight participants with insomnia disorder and without any comorbid psychiatric disorders and 29 healthy sleepers aged between 15-24 completed a monetary reward task, the Cued Door task, while electroencephalographic activity was recorded. RewP (reward minus non-reward difference waves) was calculated as the mean amplitudes within 200-300 ms time window at FCz. Two analyses of covariance (ANCOVAs) were conducted with age as a covariate on RewP amplitude and latency, respectively. RESULTS: Participants with insomnia had a significantly lower RewP amplitude regardless of cue types (Gain, Control, and Loss) than healthy sleepers, F(1, 51) = 4.95, p = 0.031, indicating blunted reward processing. On the behavioral level, healthy sleepers were more prudential (slower reaction time) in decision making towards Loss/Gain cues than their insomnia counterparts. Trial-by-trial behavioral adjustment analyses showed that, compared with healthy sleepers, participants with insomnia were less likely to dynamically change their choices in response to Loss cues. CONCLUSIONS: Dysfunctional reward processing, coupled with inflexibility of behavioral adjustment in decision-making, is associated with insomnia disorder among youth, independent of mood disorders. Future studies with long-term follow-up are needed to further delineate the developmental trajectory of insomnia-related reward dysfunctions in youth.

Associations of weekday-to-weekend sleep differences with academic performance and health-related outcomes in school-age children and youths.

Weekday-to-weekend sleep discrepancy is a common phenomenon in school-age children and youths. However, the effects of weekday-to-weekend sleep differences remain unclear. A systematic review that included 72 observational studies was conducted to examine the association of weekday-to-weekend differences in bedtime, rise time, mid-point of sleep and sleep duration with academic performance and health-related outcomes in children and youths. Weekday-to-weekend difference in sleep timing (e.g., bedtime) was associated with poorer academic performance and depressive symptoms in in youths, particularly secondary school students, and a higher risk of substance use as well as overweight/obesity in the overall samples. In addition, weekday-to-weekend difference in sleep duration showed a modest association with poorer academic performance and depressive symptoms in the overall samples, as well as a higher risk of overweight/obesity, particularly in Asian children and youths. Albeit limited evidence, greater sleep differences were related to an increased risk of behavioral problems and suicidality. Findings on the associations between weekday-to-weekend sleep differences and specific cognitive abilities, anxiety, and cardiometabolic risks were limited and inconclusive. Longitudinal and experimental studies utilizing objective sleep measures are recommended to further examine the impacts of weekday-to-weekend sleep differences on mental and physical health, and to gain more insight into the mechanisms underlying their associations.

Association of Sleep and Circadian Activity Rhythm with Emotional Face Processing among 12-month-old Infants.

Sleep and circadian rhythmicity both play an important role in human's cognitive functioning, yet the way in which early development of sleep and circadian rhythm affects cognitive processes and social learning in infants remains less understood. We examined the association of sleep and circadian activity rhythm (CAR) with face and emotional information processing in 12-month old infants. Face processing was measured by eye tracking, whereby infants' scanning patterns and pupil dilations were calculated when they were presented with neutral, pleasant and unpleasant faces. Infants with better sleep quality (i.e., less waking after sleep onset) and lower sleep-wake pattern variability (i.e., higher inter-daily stability) exhibited a higher eyes over mouth fixation ratio (EMR). Infants with longer total sleep time showed larger pupil diameter changes in response to emotional facial expressions, more closely resembling the responses of adults. Our findings suggest the role of sleep and circadian rhythm in waking cognition and have implications for understanding the early development of social learning in young children.