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Developmental biology - Infant Development

Baby Not Sleeping All Night? - No Problem!

Parents shouldn't worry if their infant doesn't sleep through the night by a year old...

A Canadian study of close to 400 infants found no association between interrupted sleep and later developmental problems. New parents often expect their baby to start sleeping through the night by around six months of age. Indeed, they often receive messages from paediatricians and others about the importance of early sleep consolidation. But authors of a study in the December 2018 issue of Pediatrics found that a large percentage of healthy babies don't reach that milestone by six months of age — or even at a year old.
The McGill University led research team also examined whether infants who didn't sleep for six or eight consecutive hours were more likely to have problems with psychomotor and mental development, and found no association. Nor did they find a correlation between infants waking up at night and their mothers' postnatal mood.

Study details

Researchers analyzed information from the Maternal Adversity, Vulnerability, and Neurodevelopment longitudinal birth cohort study, which recruited participants from obstetric clinics in Montreal, Québec and Hamilton, Ontario. Researchers defined "sleeping through the night" as either six or eight hours of sleep without waking up. Sleep was measured for 388 infants at six months old, and 369 infants at a year old.

At six months of age, according to the mothers' reports, 38 percent of typically developing infants were not yet sleeping at least six consecutive hours at night. More than half (57 percent) weren't sleeping eight hours. At twelve months old, 28 percent of infants weren't yet sleeping six hours straight at night, and 43 percent weren't staying asleep eight hours.
Researchers did see a difference between sleep patterns of boys and girls. At six months old, a slightly higher percentage of girls (48%) slept for eight hours straight versus boys (39%).

However, they found no correlation between infants waking up at night and their mothers' postnatal mood. But, they did discover that babies who didn't sleep for six or eight consecutive hours had a significantly higher rate of breastfeeding, which offers many benefits for babies and mothers.

A "gold standard" that may need to be revised

Sleeping through the night somewhere between six to twelve months is generally considered the "gold standard" in Western nations. Indeed, behavioral sleep training is popular among parents and professionals to encourage children to sleep. But, lead researcher, Marie-Hélène Pennestri, hopes that the results of the study will allay some parental worries:
"Our findings suggest parents might benefit from more education about normal development of — and wide variability in — infants' sleep/wake cycles instead of only focusing on interventions. Especially for those who feel stressed about delaying their response to infants' crying. Her sleep deprivation is often invoked to support intervention. But, it may be her expectations about being awakened at night, along with baby's total number of hours slept over the course of a day, are better predictors of maternal well-being. It is something that will be considered in future studies."

Marie-Hélène Pennestri PhD, Assistant Professor, Department of Educational and Counselling Psychology, the Sleep Clinic at Hôpital en santé mentale Rivière-des-Prairies (CIUSSS-NIM)

OBJECTIVES: Contrary to the importance of total sleep duration, the association between sleeping through the night and development in early infancy remains unclear. Our aims were to investigate the proportion of infants who sleep through the night (6- or 8-hour sleep blocks) at ages 6 and 12 months in a longitudinal cohort and to explore associations between sleeping through the night, mental and psychomotor development, maternal mood, and breastfeeding.

METHODS: At 6 and 12 months of age, maternal reports were used to assess the longest period of uninterrupted infant sleep and feeding method (n = 388). Two different criteria were used to determine if infants slept through the night: 6 and 8 hours of uninterrupted sleep. Mental and psychomotor developmental indices (Bayley Scales of Infant Development II) and maternal mood (Center for Epidemiologic Studies Depression Scale) were measured at 6, 12, and 36 months of age.

RESULTS: Using a definition of either 6 or 8 hours of uninterrupted sleep, we found that 27.9% to 57.0% of 6- and 12-month-old infants did not sleep through the night. Linear regressions revealed no significant associations between sleeping through the night and concurrent or later mental development, psychomotor development, or maternal mood (P > .05). However, sleeping through the night was associated with a much lower rate of breastfeeding (P < .0001).

CONCLUSIONS: Considering that high proportions of infants did not sleep through the night and that no associations were found between uninterrupted sleep, mental or psychomotor development, and maternal mood, expectations for early sleep consolidation could be moderated.

Marie-Hélène Pennestri, Christine Laganière, Andrée-Anne Bouvette-Turcot, Irina Pokhvisneva, Meir Steiner, Michael J. Meaney, Hélène Gaudreau, on behalf of the Mavan Research Team.

Co-authors Mark Sansom, PhD, professor of biochemistry at University of Oxford and Shanlin Rao, a graduate student in his lab, carried out molecular dynamics simulations on the different conformational states of the serotonin receptors for this study.

The authors thank the MAVAN research team. Thanks to Margaret McKyes for linguistic editing..

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Nov 21, 2018   Fetal Timeline   Maternal Timeline   News   News Archive

Babies who didn't sleep for six or eight consecutive hours had a significantly higher rate of breastfeeding, which offers many benefits for babies and mothers. Credit: indiatimes.com

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