Learning how to self-soothe is a vital skill in learning how to develop good sleeping patterns during infancy, the authors explained.
Researchers from Temple University wrote in the journal Developmental Psychology that the most common concern parents report to their pediatricians is what to do if their infant wakes up in the middle of the night.
The authors say that their findings can provide parents with "some scientific facts to help with that decision".
Psychology professor, Marsha Weinraub and team believe than in the vast majority of cases, the infant should be left to self-soothe and go back to sleep without any help.
Weinraub, an expert on child development and parent-child relationships, said:
"By six months of age, most babies sleep through the night, awakening their mothers only about once per week. However, not all children follow this pattern of development."
Weinraub and team set out to measure the patterns of night-time sleep awakenings in babies aged from 6 months to three years. They found that there are two groups of babies/toddlers:
- Sleepers - they sleep through the night without waking up. At the most, they wake up during the night just once a week.
- Transitional Sleepers - these wake up during the night much more often, sometimes seven nights per week.
Researchers suggest that most babies may be best allowed to self-soothe and fall back to sleep when they awake crying.
The researchers asked the parents of 1,200 babies to complete questionnaires on their child's awakenings when they were 6, 15, 24 and 36 months old.
The sleepers - at the age of six months, two-thirds of the babies did not wake up during the night - they were sleepers. At the most, some of them might wake up in the middle of the night just once per week. Other studies have had similar findings. Researchers from the University of Canterbury, New Zealand found that by the age of 5 months, over half of all infants were following their parents' sleeping times, and sleeping through the night.
The transitional sleepers - one third of them woke up seven nights per week when they were six months old. This figure dropped to two nights per week at the age of 15 months, and to just 1 night by the time they were two years old.
The majority of transitional sleepers were:
- Had "difficult temperaments", with such reported traits as distractibility and irritability
- Much more likely to be breastfed
- More likely to have depressed mothers
- More likely to have mothers with greater maternal sensitivity. However, according to Penn State researchers, parental emotional receptiveness can reduce sleep disruptions and help toddlers and infants sleep better.
Their findings suggest two things
- Infants with genetic or constitutional factors, such as those with "difficult temperaments", seem to have sleeping problems early on in life. Weinraub said "Families who are seeing sleep problems persist past 18 months should seek advice."
- Babies need to learn how to fall asleep unaided. If a mother tunes into these awakenings during the night, or if the infant is used to falling asleep while being breastfed, they might not be learning how to self-soothe. Knowing how to self-soothe is a vital skill for regular sleep, the authors wrote.
How strong is maternal depression linked to infant awakenings?Further research should be carried out on how the mechanism by which maternal depression is associated with infant awakenings, Weinraub said.
Mothers who have depressive symptoms when their child is 6 or 36 months old, may well have been depressed for a while, including during or even before pregnancy. This prenatal depression might have affected neural development and sleeping patterns.
Maternal depression can also be exacerbated by sleep deprivation, the authors added. Australian researchers said that there are training methods for infant sleep that are safe for the baby, improve their sleep patterns, and help improve maternal depression symptoms over the short term.
"Because the mothers in our study described infants with many awakenings per week as creating problems for themselves and other family members, parents might be encouraged to establish more nuanced and carefully targeted routines to help babies with self-soothing and to seek occasional respite.
The best advice is to put infants to bed at a regular time every night, allow them to fall asleep on their own and resist the urge to respond right away to awakenings."