Snoring toddlers with and without obstructive sleep apnoea differed with regard to snoring time, adenoid size and mouth breathing.

AIM: The difficulty of assessing the likelihood of obstructive sleep apnoea (OSA) in children who snore without full-night polysomnography is widely recognised. Our aim was to identify features that were characteristic of two-year-old children with OSA and evaluate whether this information could be used to assess the likelihood of OSA. METHODS: The study was carried out as part of the Child-Sleep Project, a longitudinal birth cohort study of children born at Tampere University Hospital, Finland. This part of the study focused on the children in the cohort who snored and was carried out between 2013 and 2015. The primary outcomes were measured using parental questionnaires, polysomnography and clinical examinations. RESULTS: In total, 52 children participated at a mean age of 27 months (range 23-34). Of these, 32 (44% male) snorers and 20 (70% male) controls. The most significant findings were that children who had OSA demonstrated longer snoring time (P = .003), a greater tendency for mouth breathing (P = .007) and bigger adenoid size (P = .008) than snorers without OSA. CONCLUSION: Snoring time, adenoid tissue size and mouth breathing were important features that identified the likelihood of OSA in snoring toddlers.

Craniofacial and occlusal development in 2.5-year-old children with obstructive sleep apnoea syndrome.

OBJECTIVES: Paediatric obstructive sleep apnoea syndrome (OSAS) is associated with a range of changes in craniofacial and occlusal development. There is, however, little knowledge of how early in life these changes can be found. The aim of the present study was to determine whether changes in dental arch morphology, occlusion, facial profile, tonsil size, breathing habit or body mass index (BMI) can already be found among 2.5-year-old children with OSAS. MATERIALS AND METHODS: Fifty-two children were recruited to the study. Of these, OSAS was diagnosed in 9 children and 18 children did not snore in polysomnography. These two groups were subsequently compared when evaluating polysomnographic, otorhinolaryngological and dental variables. RESULTS: Children with OSAS had narrower inter canine width than non-snoring children (P = 0.032). Furthermore, children with OSAS had larger adenoid size with respect to the nasopharyngeal volume (P = 0.020) and more tendency to mouth breathing (P = 0.002). No statistically significant differences were found when comparing palatine tonsil size, occlusal characteristics, soft tissue profile measurements or BMI. LIMITATIONS: The limitation of the study is the small sample size. CONCLUSION: Children with OSAS had narrower upper inter canine width than non-snoring children at the age of 2.5 years. Larger adenoid size and mouth breathing tendency were also more common among children with OSAS. Further studies with larger sample sizes are needed to determine if other changes in craniofacial and occlusal development can be found in this age group.

Season is related to the slow wave and sigma activity of infants and toddlers.

OBJECTIVE/BACKGROUND: Slow wave activity (SWA) and sigma frequency activity (SFA) are hallmarks of NREM sleep EEG and important indicators of neural plasticity, development of the central nervous system, and cognition. However, little is known about the factors that modulate these sleep EEG activities, especially in small children. PATIENTS/METHODS: We analyzed the power spectral densities of SWA (1-4 Hz) and SFA range (10-15 Hz) from six EEG derivations of 56 infants (8 months) and 60 toddlers (24 months) during their all-night sleep and during the first and the last half of night sleep. The spectral values were compared between the four seasons. RESULTS: In the spring group of infants, compared with the darker seasons, SFA was lower in the centro-occipital EEG derivations during both halves of the night. The SWA findings of the infants were restricted to the last half of the night (SWA2) and frontally, where SWA2 was higher during winter than spring. The toddlers presented less frontal SWA2 during winter compared with autumn. Both age groups showed a reduction in both SWA and SFA towards the last half of the night. CONCLUSIONS: The sleep EEG spectral power densities are more often associated with seasons in infants' SFA range. The results might stem from seasonally changing light exposure, but the exact mechanism warrants further study. Moreover, contrary to the adult-like increment of SFA, the SFA at both ages was lower at the last part of the night sleep. This suggests different regulation of spindle activity in infants and toddlers.

Sleep architecture is related to the season of PSG recording in 8-month-old infants.

To date, little is known about the impact of season on infant sleep. In higher latitudes, the duration of daily light time varies substantially between different seasons, and environmental light is one potential factor affecting sleep. In this cohort study, one-night polysomnography (PSG) was performed on 72 healthy 8-month-old infants in 2012 and 2013 to study the effect of season on the sleep architecture of young infants in Finland. The children were divided into four subgroups, according to the amount of light during their birth season and the amount of light during the season of the PSG recordings, corresponding to spring, summer, autumn, and winter. We found that the season of birth did not have an impact on the infants' sleep architecture at 8 months of age, but the season of the PSG recording did have an effect on several sleep variables. In the PSGs conducted during the spring, there was less N3 sleep and more N2 sleep than in the PSGs conducted during the autumn. In addition, there was more fragmented sleep during spring than autumn. According to our data, the season has an effect on the sleep architecture of young infants and should, therefore, be considered when evaluating the PSG findings of young infants. The exact mechanisms behind this novel finding remain unclear, however. The findings imply that infants` sleep is affected by the season or light environment, as is the case in adult sleep. Since potential explanatory factors, such as direct natural or artificial light exposure and the melatonin levels of the infants, were not controlled, more research is needed in the future to better understand this phenomenon.

Slow-wave activity and sigma activities are associated with psychomotor development at 8 months of age.

STUDY OBJECTIVES: The electrophysiological properties of non-rapid eye movement sleep (NREM) EEG are homeostatically modulated on global and local use-dependent levels. Furthermore, the local NREM quality reflects age-dependent brain maturation and individual, age-independent, and psychomotor potential. Cortical maturation and its electrophysiological marker, Slow-wave activity (SWA), as well as sleep spindles are known to change in topography and quality during the early years of life, but their associations with psychomotor development in infants are unknown. Therefore, we aimed to evaluate the local properties of SWA and spindles (sigma power) and ascertain whether they correlate with psychomotor development in 8-month-old infants. METHODS: Ambulatory polysomnographies were recorded in 56 infants at 8 months of age to calculate the local SWA and sigma powers. The associations between the SWA and sigma powers and psychomotor development (Bayley-III) were examined in 36 of these infants. RESULTS: In both hemispheres, the highest SWA and sigma powers were found occipitally and centrally, respectively, with higher powers in the right hemisphere than in the left. The Bayley-III correlated with local SWA and sigma powers: the occipital SWA and centro-occipital sigma correlated with cognitive scales, and the frontal and occipital SWA and centro-occipital sigma correlated with language and fine motor scales. Most of the correlations were unilateral. CONCLUSIONS: In 8-month-old infants, the NREM sleep quality shows local differences that are mostly attributable to the topical phase of brain maturation. The local NREM parameters correlate with psychomotor development.

Sleep architecture is related to birth season in 1-month-old infants.

Individual variation in sleep quality, quantity, and architecture is pronounced in small infants. Reasons for this remain largely unclear, even though environmental and genetic factors have been suggested to play a role. In order to study the effect of birth seasons on infant sleep architecture, 85 healthy 1-month-old infants underwent an overnight polysomnography (PSG). The PSGs were conducted in 2011-2013. The cohort was divided into four subgroups according to the amount of seasonal light at the time of birth, with each group covering a period of approximately three months. The groups were labeled IL (increasing light), L (light), ID (increasing darkness), and D (dark), corresponding to spring, summer, autumn, and winter, respectively. We found the amount of stage R sleep (precursor of REM sleep, formerly active sleep) to be the highest in infants born in summer, whereas infants born in winter presented the smallest amount of stage R sleep. Infants born in summer presented the smallest amount of stage T sleep (transitional sleep), while stage T sleep was most abundant in infants born in winter. In addition, infants born in summer showed the shortest total sleep time (TST) and the smallest number of awakenings during the study night. This was the first PSG study to find out that birth season modifies the sleep architecture of infants.

Local changes in computational non-rapid eye movement sleep depth in infants.

OBJECTIVE: Deep NREM sleep and its hallmark EEG phenomenon slow wave activity (SWA) are under homeostatic control in adults. SWA is also locally regulated as it increases in the brain areas that have been used intensively. Moreover, in children, SWA is a marker of cortical maturation. In the present study the local properties of NREM sleep depth were evaluated using the quantitative mean frequency method. We aimed to study if age is related to NREM sleep depth in young infants. In addition, we studied if young infants have local differences in their NREM sleep. METHODS: Ambulatory over-night polysomnographies were recorded in 59 healthy and full-term infants at the age of one month. The infants were divided into two age groups (<44 weeks and ≥44 weeks) to allow maturational evaluations. RESULTS: The quantitative sleep depth analysis showed differences between the age groups. In addition, there were local sleep depth differences within the age groups. CONCLUSIONS: The sleep depth change with age is most likely related to cortical maturation, whereas the local sleep depth gradients might also reflect the use-dependent properties of SWA. SIGNIFICANCE: The results support the idea that young infants have frontal cortical processing.

Variants in calcium voltage-gated channel subunit Alpha1 C-gene (CACNA1C) are associated with sleep latency in infants.

Genetic variants in CACNA1C (calcium voltage-gated channel subunit alpha1 C) are associated with bipolar disorder and schizophrenia where sleep disturbances are common. In an experimental model, Cacna1c has been found to modulate the electrophysiological architecture of sleep. There are strong genetic influences for consolidation of sleep in infancy, but only a few studies have thus far researched the genetic factors underlying the process. We hypothesized that genetic variants in CACNA1C affect the regulation of sleep in early development. Seven variants that were earlier associated (genome-wide significantly) with psychiatric disorders at CACNA1C were selected for analyses. The study sample consists of 1086 infants (520 girls and 566 boys) from the Finnish CHILD-SLEEP birth cohort (genotyped by Illumina Infinium PsychArray BeadChip). Sleep length, latency, and nightly awakenings were reported by the parents of the infants with a home-delivered questionnaire at 8 months of age. The genetic influence of CACNA1C variants on sleep in infants was examined by using PLINK software. Three of the examined CACNA1C variants, rs4765913, rs4765914, and rs2239063, were associated with sleep latency (permuted P<0.05). There was no significant association between studied variants and night awakenings or sleep duration. CACNA1C variants for psychiatric disorders were found to be associated with long sleep latency among 8-month-old infants. It remains to be clarified whether the findings refer to defective regulation of sleep, or to distractibility of sleep under external influences.

The adapted American Academy of Sleep Medicine sleep scoring criteria in one month old infants: A means to improve comparability?

OBJECTIVE: The lack of standards induces variability in the sleep staging of infants less than two months of age. We evaluated the feasibility of the 2012 AASM sleep scoring rules for healthy one month old infants. METHODS: 84 polysomnographies were scored into sleep stages with the adapted AASM criteria. The acquired sleep parameters were compared with the parameters in the literature. In addition the effect of age on sleep was studied. RESULTS: The two independent scorers achieved substantial agreement by using the adapted AASM criteria. The infants' sleep parameters showed marked variability. The amount of active sleep was 36.7% (mean, range 21.3-54.1%), quiet sleep 41.5% (30.3-57.7%) and indeterminate sleep 21.6% (9.7-36.0%). With age sleep became more continuous, but the sleep stage percentages did not change. Our sleep parameters differed clearly from the parameters presented in the literature. CONCLUSIONS: The adapted scoring rules were reproducible. This encourages their use in clinical practice, as no uniform recommendations exist. SIGNIFICANCE: Normal values are essential in pediatric sleep medicine and the individual variability in the sleep parameters of healthy infants advocates the standardisation of scoring methods. Here we present sleep stage normative values for one month old infants based on the AASM scoring criteria.