Multi-method exploration of the relationship between sleep and infant neurocognitive development

The first year of life is a time of numerous developmental milestones. At the same time an infant’s sleep under goes many fundamental changes. Research has shown that sleep can impact aspects of development; however, findings are mixed, often fail to include objective measures of both development and sleep, and longitudinal studies are missing. This project uses a multi-method approach to exploring the relationship between sleep and neurocognitive development in the first year of life. For this purpose, longitudinal and cross-sectional experimental designs were combined with a multitude of objective and subjective methods (such as electroencephalography(EEG), actigraphy, eye-tracking, near-infrared spectroscopy(NIRS), parent-report questionnaires),and analysis approaches (cluster analysis, mixed modelling, and functional connectivity analysis). Key insights from the longitudinal study showed that cross-method agreement between different sleep measures varied depending on sleep parameters, infant age, and maternal stress. Moreover, sleep measurement choice can influence how the relationship between sleep and development is described. Associations with behavioural and parent-report measures of infant development were fragmented. However, a clearer cross-method consistent picture emerged with regard to brain measures that highlighted the importance of studying sleep fragmentation. The study also underscored the need to study the relationship between sleep and development continuously as there was evidence for age-related changes in the association between sleep and development. The second, cross-sectional study contributed a new methodology to studying the relationship between sleep (quality) and neurocognitive development. A customised NIRS-EEG system was used as a novel way to study infant brain activity during sleep. This project enables further research into sleep in a developmental context including the potential use of a wireless NIRS-EEG system to study sleep in naturalistic settings and of sleep fragmentation as a target for sleep-based interventions for children with neurodevelopmental disorders

Developing customized NIRS-EEG for infant sleep research: methodological considerations

Significance: Studies using simultaneous functional near-infrared spectroscopy (fNIRS)-electroencephalography (EEG) during natural sleep in infancy are rare. Developments for combined fNIRS-EEG for sleep research that ensure optimal comfort as well as good coupling and data quality are needed. // Aim: We describe the steps toward developing a comfortable, wearable NIRS-EEG headgear adapted specifically for sleeping infants ages 5 to 9 months and present the experimental procedures and data quality to conduct infant sleep research using combined fNIRS-EEG. // Approach: N = 49 5- to 9-month-old infants participated. In phase 1, N = 26 (10 = slept) participated using the non-wearable version of the NIRS-EEG headgear with 13-channel-wearable EEG and 39-channel fiber-based NIRS. In phase 2, N = 23 infants (21 = slept) participated with the wireless version of the headgear with 20-channel-wearable EEG and 47-channel wearable NIRS. We used QT-NIRS to assess the NIRS data quality based on the good time window percentage, included channels, nap duration, and valid EEG percentage. // Results: The infant nap rate during phase 1 was ∼40 % (45% valid EEG data) and increased to 90% during phase 2 (100% valid EEG data). Infants slept significantly longer with the wearable system than the non-wearable system. However, there were more included good channels based on QT-NIRS in study phase 1 (61%) than phase 2 (50%), though this difference was not statistically significant. // Conclusions: We demonstrated the usability of an integrated NIRS-EEG headgear during natural infant sleep with both non-wearable and wearable NIRS systems. The wearable NIRS-EEG headgear represents a good compromise between data quality, opportunities of applications (home visits and toddlers), and experiment success (infants’ comfort, longer sleep duration, and opportunities for caregiver–child interaction)

Developing customized NIRS-EEG for infant sleep research: methodological considerations

Significance: Studies using simultaneous fNIRS-EEG during natural sleep in infancy are rare. New developments for combined fNIRS-EEG for sleep research are needed that ensure optimal comfort whilst ensuring good coupling and data quality. Aim: We describe the steps towards developing a comfortable, wearable NIRS-EEG headgear adapted specifically for sleeping infants ages 5-9 months and present the experimental procedures and data quality to conduct infant sleep research using combined fNIRS-EEG. Approach: N=49 5-to-9-months-old infants participated. In phase 1, N=26 (10=slept) using the non-wearable version of the NIRS-EEG headgear with 13-channel-wearable EEG and 39-channel fiber-based NIRS. In phase 2, N=23 infants (21=slept) with the wireless version of the headgear with 20-channel-wearable EEG and 47-channel-wearable-NIRS. We used QT-NIRS to assess NIRS data quality based on: good time window percentage, included channels, nap duration and valid EEG percentage. Results: Infant nap rate during phase 1 was ~40% (45% valid EEG data) and increased to 90% during phase 2 (100% valid EEG data). Infants slept significantly longer with the wearable system than the non-wearable system. However, there were more included good channels based on QT-NIRS in study phase 1 (61 %) than 2 (50 %), though this difference was not statistically significant. Conclusions: We demonstrated the usability of an integrated NIRS-EEG headgear during natural infant sleep both with a non-wearable and wearable NIRS system. The wearable EEG-NIRS headgear represents a good compromise between data quality, opportunities of applications (home visits, toddlers) and experiment success (infants’ comfort, longer sleep duration, opportunities for caregiver-child interaction)

Infant sleep predicts trajectories of social attention and later autism traits.

BACKGROUND: Children with neurodevelopmental disorders including autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) often experience sleep disturbances, but little is known about when these sleep differences emerge and how they relate to later development. METHODS: We used a prospective longitudinal design in infants with a family history of ASD and/or ADHD to examine infant sleep and its relation to trajectories of attention and later neurodevelopmental disorders. We formed factors of Day and Night Sleep from parent-reported measures (including day/night sleep duration, number of naps in the day, frequency of night awakenings and sleep onset problems). We examined sleep in 164 infants at 5-, 10- and 14-months with/without a first-degree relative with ASD and/or ADHD who underwent a consensus clinical assessment for ASD at age 3. RESULTS: By 14-months, infants with a first-degree relative with ASD (but not ADHD) showed lower Night Sleep scores than infants with no family history of ASD; lower Night Sleep scores in infancy were also associated with a later ASD diagnosis, decreased cognitive ability, increased ASD symptomatology at 3-years, and developing social attention (e.g., looking to faces). We found no such effects with Day Sleep. CONCLUSIONS: Sleep disturbances may be apparent at night from 14-months in infants with a family history of ASD and also those with later ASD, but were not associated with a family history of ADHD. Infant sleep disturbances were also linked to later dimensional variation in cognitive and social skills across the cohort. Night Sleep and Social Attention were interrelated over the first 2 years of life, suggesting that this may be one mechanism through which sleep quality influences neurodevelopment. Interventions targeted towards supporting families with their infant's sleep problems may be useful in this population