A note on vowel patterns in two normally developing children

The present paper reports on vowel patterns in two normally developing children, aged 1; 10–2;0 and 2;0–2;2 (years;months;days), during the period of the investigation. The study was undertaken to analyse vowel patterns not previously identified as being widespread among children (Stoel-Gammon and Dunn, 1985). Results indicated the existence of patterns involving [ai], height errors among front vowels, and resyllabification of long vowels.     

A note on vowel patterns in two normally developing children

The present paper reports on vowel patterns in two normally developing children, aged 1; 10-2;0 and 2;0-2;2 (years;months;days), during the period of the investigation. The study was undertaken to analyse vowel patterns not previously identified as being widespread among children (Stoel-Gammon and Dunn, 1985). Results indicated the existence of patterns involving [ai], height errors among front vowels, and resyllabification of long vowels.     

Variability of normal sleep patterns in 40 consecutive ambulatory sleep-wakefulness records.

Sleep-wakefulness (S-W) patterns were recorded continuously for 40 consecutive 24 h using subcutaneous chronic electrodes and an ambulatory cassette recorder in a healthy 57-year-old volunteer. Variability of sleep patterns was assessed in steady-state conditions and in the course of a scientific journey encompassing flights in both west/east and south/north directions. Data were compared with findings from age-matched laboratory control records. Polysomnographic evaluation of our sleep data shows: (1) Stability of the first 3 sleep cycles and variability of the remaining sleep period with respect to both duration and structure. Vulnerability of REM sleep to environmental interference. (2) Stability of the WASO/drowsiness cluster as an intraindividual biological trait independent of social interactions. The clinical relevance of ambulatory serial recording is stressed. (3) The role of the first sleep cycle structure in the chronobiological adaptation process is documented. Apparently travelling in south/north directions may have similar or even more polygraphic implications than west/east transfer.     

Aberrant sleep patterns in children with the Rett syndrome

Previous studies on the characteristics of disturbed sleep/wake patterns in children with the Rett syndrome have yielded inconsistent findings. In the current study, momentary time sampling procedures were used to measure the sleep/wake patterns of 20 girls with classical Rett syndrome. These patients had significantly more total sleep than age peers (M = 110.1; Zm = 2.58; p = .01), significantly less nighttime sleep (M = 80.8; Zm = -7.53; p less than .0001), and significantly more daytime sleep (M = 24.5; Zm = 8.71; p less than .0001). Night sleep was negatively correlated with age (r = -.59; p less than .01); day sleep was positively correlated with age (r = .54; p = .01). These girls also displayed night wakings on 20.9% of nights, delayed sleep onset on 67.8% of nights and early wakings on 24.5% of nights. These data clearly demonstrate that children with the Rett syndrome have markedly impaired sleep/wake patterns and suggests that the sleep dysfunction may worsen over time.     

Short-term effects of fluoxetine and trifluoromethylphenylpiperazine on electroencephalographic sleep in the rat

Fluoxetine and trifluoromethylphenylpiperazine (TFMPP) were studied for their short-term effects on electroencephalographic sleep in male rats. Following single injection, each drug produced a sizeable, dose-related suppression of rapid-eye-movement (REM) sleep that persisted for 4-5 h (fluoxetine, 0.625-5 mg/kg; TFMPP, 0.10-1.25 mg/kg). TFMPP also consistently increased non-REM (NREM) sleep during the second hour after drug injection, though this effect was not dose-related (it was seen at all doses tested). Fluoxetine produced small effects on NREM sleep that varied non-systematically with dose and time after drug injection. TFMPP, but not fluoxetine, also increased at all doses the number of delta waves per minute of NREM sleep in the second hour. A structural analog of TFMPP that is inactive at serotonin (5-HT) receptors [4-(m-trifluoromethylphenyl)piperadine; LY97117] was also tested, and found to be devoid of effects on NREM and REM sleep. Both fluoxetine (a 5-HT reuptake blocker) and TFMPP (a 5-HT agonist) enhance transmission across 5-HT synapses, though by different mechanisms. Because they have the common effect of suppressing REM sleep, and in a dose-related manner, the data support the notion that 5-HT neurons in the brain, when active, can suppress REM sleep.     

A polysomnographic study of sleep patterns in normal humans with low- or high-anxiety personality traits

To clarify the effects of anxiety-related personality traits on sleep patterns, polysomnographic examinations (PSG) were performed over 4 consecutive nights on normal humans who tested within the low- or high-anxiety ranges. The subjects consisted of two groups of six male university students who scored either less than 45 points (low-anxiety group) or more than 55 points (high-anxiety group) on the Spielberger's State Trait Anxiety Inventory. Compared to the levels of sleep change in the high-anxiety group, the low-anxiety group exhibited a greater change in REM sleep and stage 2 sleep. The REM sleep in the low-anxiety group was shorter on the first and second nights compared to the third and fourth nights, and the stage 2 sleep was longer on the first night than on the remaining three nights. Thus, the low-anxiety group showed a first-night effect followed by partial recovery on the second night, while the high-anxiety group exhibited no obvious first-night effect. These results suggest that there is a difference in sleep patterns, assessed by consecutive PSG, between those with low- and high-anxiety traits, and that anxiety-related personality traits attenuate the occurrence of the first-night effect, reflecting a lower adaptability to a novel environment.     

Effect of hippocampectomy on sleep patterns in cats.

The study was planned to see if the hippocampus has an influence on fast wave sleep (FWS) as well as on slow wave sleep (SWS). From 8 male cats EEG, EMG and EOG were recorded for 24 h, first under normal conditions, secondly after cortical damage to the dorsal marginal portion of posterior ectosylvian gyrus, and thirdly following hippocampectomy done through the cortical damage. From the records, SWS, FWS and the sleep state (defined as a sequence of SWS or SWS-FWS phases between two successive waking states) were measured in terms of their occurrence, the mean duration and the total time they occupied in the day, night and 24 h. In addition, sleep sequences were classified according to the number of constituent sleep phases. Cortical damage did not affect SWS, FWS, or sleep state with regard to their occurrence, the mean duration, and the total time they occupied in 24 h. Nor did it affect the proportion of short and long sequences. The circadian variation of sleep was clearly retained. Hippocampectomy significantly reduced the total time occupied by sleep state, SWS and FWS, increased the occurrence of sleep state and SWS phase against decreased incidence of FWS phase, and reduced the mean duration of sleep state and SWS phase. Hippocampectomy also significantly increased the occurrence of sleep sequences with only one SWS phase at the cost of sequences with alternating SWS and FWS phases. Following hippocampectomy, the circadian variation of sleep was not only retained, but actually exagerated. The hippocampus in inferred to facilitate the FWS as well as the SWS phase of sleep.     

Determinants of sleep patterns in healthy Japanese 5-year-old children

Background

Early childhood is an important period for the development of sleep patterns; studies of sleep patterns in young preschool children may help elucidate the mechanism of associated mental/physical conditions and later sleep problems.

Aim and methods

The aim of this study was to investigate intrinsic and extrinsic independent variables associated with sleep patterns in preschool children using actigraphy. Forty-eight 5-year-old children from two types of nurseries, which accommodate children with (Type A) or without (Type B) in-home caregivers, were invited to undergo a 7-day actigraphic sleep study.

Results

Compared with weekdays, both sleep onset time and sleep end time were later on weekends (28 and 17 min later in average, respectively). On weekdays, cultural lessons were associated with a later sleep onset time (22 min later); female gender, sports lessons and fixed bathing times were related with an earlier sleep end time (17, 21 and 17 min earlier, respectively); sports lessons were also associated with higher sleep efficiency (3.7% higher). During weekends, unfixed bedtimes and daytime naps were related with a later sleep onset time (73 and 54 min later, respectively); male gender, Type A nursery and daytime naps were associated with a later sleep end time (33, 37 and 34 min later, respectively); sports lessons were associated with higher sleep efficiency (3.6% higher).

Conclusions

Our current findings suggested that both intrinsic and extrinsic factors, such as gender, child care, lifestyle and after-nursery lessons, influence the establishment of sleep patterns in young preschool children. Further investigation of these independent variables may help establish a strategy for predicting and preventing sleep disorders later in life.