A common misconception of sleep training that some parents have is that it causes stress in babies.

This deters many parents from giving sleep training a try. The hesitation is understandable because most parents would rather have sleepless nights than do anything that might negatively harm their baby.

However, this wrong information comes primarily from a study done in 2012 by researcher Wendy Middlemis from University of North Texas’s College of Education. She studied 25 pairs of mothers and infants currently enrolled in a sleep training program. The babies were four to ten months old.

The mothers spent the day with their infants and then helped prepare them for naptime and bedtime. They stayed in the hallway outside the room where they could hear their babies but were out of sight. Hospital nurses put the infants down in their cribs and let them cry without comforting or soothing them. This study was repeated for four days.

Middlemis then measured the cortisol levels of the mothers and babies on the second and fourth nights. Cortisol is a hormonal marker of stress. The study tested the cortisol levels right before bedtime and then 20 minutes after the babies had fallen asleep. She concluded that infants experienced physiological distress, as shown through the increase in cortisol, and that sleep training leads to a mismatch between mother and infant cortisol levels.

However, this research is flawed, and many people have pointed out that it does not give conclusive evidence for its claims. There are several reasons for this. First, there was no control group, which is the standard in conducting a scientific study. She did not compare the results of the sleep-trained babies compared to babies who were not being sleep trained. Because of this, the study cannot conclude that it was the sleep training that caused the infants’ elevated cortisol levels. It could have also been caused by being in unfamiliar surroundings (a hospital and not at home) and being put to sleep by a stranger (the nurse).

This study also has other issues. The study’s small sample, only 25 babies, and only two days of cortisol measurements is not enough evidence to draw general conclusions. More importantly, the study does not represent the typical sleep training experience. If it was meant to study the effects of sleep training, the babies should have been at home with their parents acting as the primary caregivers putting them to sleep.

Aside from this, it is expected that a child going through an adjustment or new situation will experience a spike in cortisol. We can assume that this increase in cortisol can happen in many other conditions – meeting new caregivers, a doctor’s visit, or even joining a new playgroup. These everyday situations include learning how to sleep independently. These reasons are why this study is not a reliable basis for the effect of sleep training on babies.

So, to answer the question, “Does sleep training cause stress?”

The short answer is no, it doesn’t. Further proof of this is five-year studies that suggest that sleep-trained children have no attachment, emotional, or mental health differences compared to those who have not been sleep trained. Some studies even suggest an increase in secure attachment behaviors after sleep training. This is most likely because parents are less tired, have gotten more sleep, and generally have more patience to care for their babies.

If sleep training sounds right for your family, get in touch with a sleep training expert who can guide you through helping your child sleep independently. Rest assured that sleep training does not cause undue stress on your baby and having a well-rested baby will result in a happy and healthy family.

If your baby is struggling with sleep and you’re wanting to explore options to improve it, please use the link below to book a Free 15 minute discovery call with one of our team members. Louise and Hannah have helped over 1500 families in Singapore and beyond achieve improved sleep for their baby’s. And we’d love the opportunity to help you too!