| [OBJECTIVE] The longitudinal study mainly aimed to understand the infantile sleep/wake pattern developmental trajectory in the home setting, explore the characteristics of sleep/wake pattern which benefited infantile growth and development. Also, parental sleep-related caring behaviors in Chinese culture context, the influences on infantile sleep/wake patterns were comprehended.[METHODS] It was a longitudinal study, which tracked the sleep/wake pattern development trajectory and parental sleep related caring behaviors of 473 healthy infants in the first year of life in the home setting. Both Acti-watch and parental sleep log were employed. Meanwhile, infantile physical growth and cognitive development were monitored. Other covariates such as infantile feeding, disease, temperament, and parental emotion and demographics were collected. Two-level random effect model was adopted to analyze the trend of infantile diurnal and nocturnal sleep parameters changing with age, and to explore the influences of infantile sleep/wake pattern on growth and development. Similar random effect model was applied to systematically describe the demographic distribution characteristics of parental sleep-related caring behaviors, and their influences on infantile sleep development.[RESULTS]1. Based on 473 included subjects, the changing trend of daytime sleep/wake related parameters presented as the number of naps decreaseing, duration of naps shortening along with infants’age increasing, while the duration of wake between two naps lengthening with age. On the 10 day after birth, infants took 4.0 naps on average, each interval for nap and wake lasted for about 145.0 minutes and 77.7 minutes respectively on average. Nap proportion was about 60.1%, which meaned the total duration of daytime naps accounted for about 60.1% of daytime defined by parent. At the age of 6-month old, number of naps decreased to 3.0 times, the average duration for each nap were shortened by 50% and wakes were 1.3 times lengthened compared with 10th day. Nap proportion decreased to 25.5% at this age. At the age of 12-month old, infants take two naps on average, the duration of each nap lasted for108.0 minutes, and the wake interval between two naps lasted for 247.2 minutes on average. The nap proportion was 23.1%. Concerning the nighttime sleep/wake patten, the latency of infants’sleep onset decreased with age, from 66.8 minutes on 10th day to 15-18 minutes at 6-12 months old. During the nocturnal sleep, the number of night wakes and the duration of each night wake also decreased with age, while uninterrupted sleep periods lengthened with age. On the 10th day, infants’longest continuous sleeping interval was 227.6 minutes, and the average duration of sleep interval was 136.0 minutes. There were 3 times of nightwaking on average, and each nightwaking between two sleep periods lasted for 32.3 minutes on average. At 12-month old, infants could sleep continuously for 350.9 minutes at most on average. Mean duration of each sleep interval increased to 268.1 minutes, while each nightwaking was shortened to 19.3 minutes and the number of nightwaking decreased to 1.6 times per night on average. Generally, nighttime sleep efficiency increased from 66.3% on the 10th day to 86.3% at 12-month old. Also the physical activity level increased over time.2. The differences of sleep/wake patterns between boys and girls presented as boys’ nocturnal longest uninterrupted sleep period was 19 minutes shorter, the physical activity level during nighttime sleep was 0.6 units higher and the average nighttime sleep efficiency was 2.23% lower compared with girls respectively. There were no significant gender differences found in other nocturnal sleep related parameters and the diurnal sleep status.3. After adjusting for the relevant confounding factors’ effects, sleep parameters including number of nightwaking, duration of nocturnal longest uninterrupted sleep period, nighttime sleep efficiency, physical activity level during nighttime sleep and number of naps and nap proportion had significant influences on infantile physical growth such as weight, length, BMI and related growth velocity. And except naps proportion, other five sleep parameters all presented positive influences on physical growth. For instance, as to infants’ weitght, with the number of nightwakings or naps increased by one time, or sleep efficiency increased by 5%, infants’ weight increased by 22.5g,40.6g, and 63 g respectively, while decreased by 56g with nap proportion added by 5%. On infant’s length, the average values increased by 0.1cm,0.0cm, and 0.1cm respectively with the increasing nocturnal sleep efficiency, physical activity level or number of naps, and also reduced by 0.2cm when the nap proportion added. As regard to cognitive development, sleep efficiency increased by 5%, the Mental Development Index(MDI) increased by 0.4 on average. On the contrary, MDI decreased by 1.5 on average with the number of naps increased by one time, and Psychomotive Development Index(PDI) decreased by 0.7 with the nap proportion added by 5%. The influences of other sleep parameters on infantile cognitive development were not statistically significant.4. As regard to parental caring behaviors, the routine activities performed 1 hour before sleep were feeding milk of 90.0%, bath of 53.6%, parent-child interactivity of 34.9%, massage of 21.0%, and feeding solid food of 7.1% on average.57.2% of infants were placed in bed when fully asleep.82.6% of infants falled asleep with the accompanying of parents or being patted or swayed by parents.73.5% of infants falled asleep while milk feeding. Only 18.7% of infants falled asleep by themselves. More than a half of the infants sleep with the lights on. With respect to sleep location,62.3% of infants co-sleeped with parents,31.8% sleeping in their own crib but sharing room with parents, and 1.6% sleeping in their own crib and own room. During nocturnal sleep,87.1% of infants used paper diaper on average. Infants’gender and temperament characteristics, parents cultural degree and emotional status, and family incomes had significant influences on parental sleep-related caring behaviors. The families that infants ’father’s cultural degree was low, accompanied with depression tendency, were more likely to take unhealthy rearing behaviors.5. The association analysis between parental caring behavior and infant sleep/wake patterns shown that bath per-sleep, falling asleep by himself, falling asleep with parents’presence or being patted or swayed, the mental state when being placed to bed, sleep location and types of diaper used during nocturnal sleep were major influence factors of infant sleep/wake patterns. For instance, infants having bath before sleep had higher sleep efficiency by 0.7% on average. Compared with infants co-sleep with parents, infants sleeping in his own room or sleeping in parents’room but his own crib had 0.57 and 0.20 less times of nightwaking respectively, the duration of longest uninterrupted sleep period were 24 minutes and 7 minutes longer respectively, and the sleep efficiency were 2.78% and 0.81% higher respectively. Similarly, compared with infants who were placed to bed after fully asleep, infants placed to bed when fully awake or when drowsy had 0.19 and 0.10 less number of nightwaking respectively, and the duration of longest uninterrupted sleep period increased by 12 minutes and 6 minutes respectively. Infants falling asleep when being accompanied or patted by parents had shorter duration of longest uninterrupted sleep period, and infants who falled asleep alone by themselves had 1.21% higher sleep efficiency.[CONCLUSIONS]1. Infantile sleep/wake pattern undergo obvious changing during the first 6 months after birth. Boys present relative weak ability to maintain an uninterrupted sleep, and lower sleep efficiency compared with girls. Compared with previous results from other countries, most of infants included our study seem to delay achieving an uninterrupted sleep, and also present longer of sleep latency during the first 6 months of life. The difference shown above could be the demonstration of cultural difference or could be resulted from the study methods, sample size or the instruments selected by different researches.2. The high nocturnal sleep efficiency and good ability of uninterrupt sleep present beneficial to infants’s phycial growth and cognitive development. Appropriate numbers of nightawaking are also necessary for infants’physical growth. However, the effects of diurnal sleep/wake patterns on infants physical growth are inconsistent with that on conginitive development, which remains to be further confirmed.3. The reference data and curve of infants’sleep/wake patterns obtained in this study are based on both healthy physical growth and cognitive development. We hope it will benefit our infants sleep health care to promote the positive developments of infantile sleep.4. Bathing before sleep, placing infant to bed when fully awake or drowsy, having infant sleeping in his own crib regardless of in a shared room or in his own room, using diaper during nocturnal sleep as well as avoiding unhealthy soothing behaviors such as falling asleep while being accompanied or patted by parents or feeding milk, all these caring behaviors will be helpful to promote a healthy sleep/wake pattern of infants.5. In the field of pediatric sleep research in China, this study was firsty combined using subject and object methods in the home environment condition to study infant sleep. Also our study covered the largest sample size among similar studies so far. This study not only provide rich experiences for future further infantile sleep related researches in China, but also update the relevant data accumulation in this field. |
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