The first dilemma facing many new parents is: do I let my baby cry at night or do I run to lift and comfort him?
A new study in the United States found what it says is scientific evidence of why it is better to let them cry "until the dream overcomes them".
Many babies at six months of age begin to sleep through the night, and usually awaken their parents once a week.
But not all children follow this pattern of development. And some continue to present a dream interrupted for months.
In fact, as researchers say in Developmental Psychology, these sleeping difficulties are one of the main concerns for parents to consult their pediatricians.
For the research, Marsha Weinraub, a psychology professor at Temple University and her team measured the sleep and wakefulness patterns during the night of a group of 1,200 infants between six and 36 months of age.
They asked the parents to keep track of the times their baby woke up on their 6th, 15th, 26th and 36th month.
The results showed that babies could be divided into two groups: sleepers and transient sleepers.
It was found that at 6 months of age, 66% of the sleeping babies did not wake up during the night or wake up only once a week, and then follow a similar path as they grow up.
But 33% of transient sleeping babies, when they turned 6 months old, woke up seven nights a week, at 15 months they woke up two nights a week and a night when they turned 24 months.
The researchers also found that most of the babies that woke up were male and many were being breastfed.
Learning alone to calm down
The babies were also subjected to temperament tests to measure factors such as irritability and distraction.
The results showed that transient sleepers had higher levels of temperamental difficulty.
According to Dr. Weinraub, an expert in child development, sleep problems at the beginning of life could have two explanations.
One is that perhaps there are genetic or biological factors, such as those reflected in a difficult temperament, that have an impact on the difficulty of sleeping.
And the other, Dr. Weinraub says, is that many babies have not learned by themselves how to fall asleep, especially when they are breastfed.
"When mothers adapt to this nocturnal awakening and / or if the baby has the habit of falling asleep during breastfeeding, then he is not learning how to calm down on his own, and this is essential to have a regular sleep" explains the researcher .
But the authors accept that there may be other factors, such as maternal depression, that also have an impact on the baby's sleep.
For example, it is not known if a mother who is depressed when the baby is six or 36 months old was also depressed during pregnancy and this could have had an impact on the neural development of the baby and therefore on their sleeping problems.
Or, on the other hand, the mother's depression could be exacerbated by the lack of sleep caused by the baby's nocturnal interruptions.
More studies
To find answers to these questions, says Dr. Weinraub, more studies will be needed.
For now, he says, "we recommend that parents establish a thorough and carefully prepared routine to help the baby calm down," says the psychologist.
"The best advice is to place the infants in their bed at a regular time each night, let them fall asleep on their own and resist the urge to respond immediately to their cries."
"Families that continue to experience sleep problems after the baby turns 18 months should consult an expert" adds the researcher.