The short and long term consequences of controlled crying are under the spotlight, with new Australian research suggesting no harm results from the practice.
The study, led by Flinders University sleep expert psychologist Michael Gradisar, found controlled crying - where the child is left to cry for gradually increasing periods of time before being comforted - and other sleep training methods were unlikely to cause the behavioural, emotional or parent-child attachment issues many parents fear.
Dr Gradisar said while it was natural for parents to worry about their child crying at bedtime, his study of 43 infants who remained troubled sleepers beyond six months of age showed controlled crying improved sleep without having any detrimental effects on the child or family.
"We're hoping these results will add another element to how parents view their responses and how they manage their own and their babies' sleep behaviour," Dr Gradisar said.
However opponents of controlled crying were critical of the study and pointed to the fact it only involved a small number of babies aged between 6 and 16 months.
Baby sleep expert Pinky McKay told Essential Baby she feared the study would make parents whose newborn babies were not sleeping well feel like they were failing.
"I think we would be much better off supporting mothers and families and finding out why these babies are waking and crying rather than making them sound like an inconvenience," the certified lactation consultant and author of Sleeping Like a Baby said.
"There could be any number of reasons the babies are crying. I just don't understand why we would suggest those needs should be ignored for the sake of an extra 13 minutes of sleep."
The infants in the study aged six to 16 months had been identified by their parents as troubled sleepers. They were separated into three groups, each of which tried a different sleep education technique.
The first group used graduated extinction, a method which babies are left to cry for short, set timeframes over several nights.
The second group used the "gentler" bedtime fading technique, which delays the infant's bedtime by 15 minutes so the child becomes more tired by bedtime.
The third group in the study was the control group, which was given sleep information.
Dr Gradisar said the infants whose parents used the graduated extinction method on average fell asleep 13 minutes earlier and woke up less often during the night than those in the control group.
Meanwhile, there was no significant difference reported between the stress levels of parents and babies based on saliva testing for stress hormones.
The babies in the bedtime fading group fell asleep 10 minutes earlier than those in the control group.
However Dr Gradisar said there was no change to the number of times a night the infant woke compared to the third group.
A follow-up with parents 12 months on established that there were no significant differences in emotional or behavioural problems - or in attachment styles between parent and child.
Ms McKay was also critical of the method used to assess the impact of controlled crying on the long term development of a child.
"Twelve months really isn't a very long time to make a finding like that," she said.
"Also, parental attachment is a very hard thing to measure, and parents are known to be very subjective."
Bed-sharing was not included in the study due to safety concerns, though room-sharing could be another technique for parents wanting to introduce sleep training, Dr Gradisar said.