Sleep training is a stressful period in many parents’ life. However, there are several misconceptions about whether the stress caused in babies during sleep training is harmful to their health or not. Some parents fear that leaving their infant cry while trying to teach her how to soothe herself to sleep may bring neurological damage because they have heard that stress can flood the brain with cortisol, altering development and killing neurons.  

The truth is that no parent likes to hear their baby cry. It is something that makes usparents, feel stressed; let alone the baby. But, there is more than meets the eye here. Do we really know how stressful sleep training it (if at all)? Does it really affect the infant’s brain in adverse ways?   

To be able to speak the truth about this situation, it is crucial that we set things straight because there is a lot of misinformation out there on stress in general. You see, all the research supporting that letting a baby cry is damaging to their brain refers to children that have been subjected to chronic abuse or neglect and babies that lack strong attachment figures. These are all examples of toxic stress.  

Categorising Stress  

There are numerous studies talking about adverse experiences and the effects they have on the brain. According to The National Scientific Council on the Developing Child, there are 3 levels of stress: 

  1. Positive stress 

Positive stress is an imperative part of healthy development. It refers to short-lived situations that include dealing with frustration, such as when receiving an immunisation shot or on the first day at a child care centre. They are characterised by mild increases in hormone levels and heart rate. In case of a baby, with the caregiver’s support and buffering, the child quickly deals with the stressor and the stress response system returns to baseline status. Overall, positive stress is an element that promotes a child’s normal development and provides excellent opportunities to learn and practice positive, adaptive responses to negative experiences.   

  1. Tolerable stress  

Tolerable stress calls the body’s stress response system to be even more alert than in positive stress responses. It is the kind of stress experienced during situations that involve a longer-lasting, greater level of grief or difficulty, like the death of a family member, a natural disaster or a serious illness. However, with the support and protection of an adult, the risk that such experiences lead to long-term consequences for learning and health, along with psychological harm, is significantly reduced. It has been found that the brain and other organs of the body quickly recover after tolerable stress responses. So, what makes this form of stress categorised as tolerable in children significantly relies on the extent to which the relationship between the child and the parent helps the child cope with the stressor and regain control of herself.  

  1. Toxic stress 

This is the most dangerous and health-affecting form of stress response. Toxic stress can occur when a child experiences long-lasting or more frequent or stronger (difficult) events without enough support from a nurturing adult. It is most common among cases of maternal depression, drug abuse, child abuse, and neglect, among others. When under toxic stress, the body’s stress response system kicks in rapidly and the body is unable to restore hormonal balance. If this goes on for prolonged periods of time, especially during milestone developmental stages, it could disrupt a child’s development and lead to impaired learning and memory, as well as stress-related mental and physical illness, including neurological damage and permanent changes in the function of the brain. During the child’s later developmental stages, toxic stress can affect her decision-making, mood, ability to learn new skills, and impulse control.  

So, the question here is where does sleep training fall? Are you more likely to relate it to being raised by a person that abusing drugs, coping with a divorce between two people you love dearly, or getting a child vaccinated (or starting school)? Will you classify sleep training stress under toxic, tolerable or positive stress category? 

In the majority of families, sleep training is miles away from the sad situations that cause toxic stress (or even tolerable stress). In fact, most moms and dads find out that sleep training is a brief process that lasts a few nights, and up to a couple of weeks if sleep training is done more gradually. If it causes more than a few weeks of prolonged crying, though, you should reconsider your strategy and find a new method to help the little one.  

Babies’ Response to Positive Stress 

Every time we experience stress, the body activates a mechanism to help us calm down. One of the ways our own system tries to balance things for us again is through activating the HPA (Hypothalamic-Pituitary-Adrenocortical) axis, which results in the production of cortisol – a hormone that is vital for our survival as it allows us to recover from stress and cope with the stressor.  

Babies’ HPA axis is extremely reactive at birth. This means that an infant will have an increased cortisol production during situations like a physical exam, a bath or a heel stick. One study gave newborns a mock exam for two consecutive days. On the first day, the babies cried and had elevated cortisol levels during the exam. Interestingly, on the 2nd day, when they also underwent a similar physical exam, the babies did cry as much as they had the previous day, but their cortisol levels did not show any increase. Somehow, their brain realised that the particular experience was re-lived and was able to recover (and learn) from the experience. Next time, they would be able to cope with the same “stressor” (in our case, the physical examination) even more effectively. This illustrates a positive stress response and also shows that crying and increased cortisol do not always go hand in hand.  

Undeniably, crying is an infant’s way of communicating. Nevertheless, don’t think that it only expresses despair. As a matter of fact, crying can be a self-soothing behaviour that may reduce the activity of the cortisol response and release tension. Therefore, being supportive towards the baby and lovingly allow her to practice stress coping as part of learning a new skill, you actually do your child a good thing that promotes her healthy development.  

Why Control Crying is Okay 

The key to bearing the beneficial effects of positive stress is to allow the parent to buffer the tension until the baby learns how to deal with stress. And, by tension, we mean temporary, short-lived stress – not frequent or prolonged activation of stress hormones. For that reason, knowledgeable baby sleep consultants that respect their job will never ask a parent to leave their baby alone to cry for hours non-end every night. Instead, we focus on gentle approaches that gradually allow the baby to develop its own soothing mechanisms and eventually fall to sleep on her own (and sleep through the night).  

Note: It is very easy to misunderstand the wording, which is a huge part of the problem here. You see, prolonged crying can indeed have negative impacts like the ones mentioned above. However, when advising parents to let their baby cry a couple of hours over a few nights, this is NOT prolonged crying. It is part of a healthy, essential process the child has to go through so that she learns to self-settle, and for the various other benefits we have already talked about.   

Quoting Interesting Facts  

  • Babies with fragmented sleep have higher cortisol levels in the morning and are more likely to break into tears or become upset in response to small challenges and stressors at daycare.  
  • Babies whose mothers are depressed due to sleep deprivation have higher cortisol levels (chronically) in preschool and adolescence.  
  • The cortisol in babies between 3-6 months old that play with a sensitive parent drops compared to when playing with an insensitive parent. If a parent’s ability to respond with love and support to the child’s needs is affected by sleep deprivation, the child’s exposure to cortisol could increase.  

As you, loving mothers, can see, sleep training your baby is not an act of selfishness. It is a perfectly reasonable and approved way to help you be an even more responsive parent and give you the chance to cope with the stressors of life better.  

Some Final Thoughts 

Sleep training involves decreasing both some crying and parental involvement. Learning to fall asleep on their own does not come easy for many babies. However, being there for your infant in a nurturing, soothing way will help her adjust her biological clock and figure out how to self-soothe to sleep.  

Childhood stress should be put in context. Yes, making changes to her bedtime routine is stressful for her. Nut, it is important to recognise that this is temporary stress and has nothing to do with toxic stress that is the root of so many serious problems, health and mental ones. That aside, toxic stress is caused by long-term exposure to a stressor with a lack of necessary support to cope with it. Sleep training stress lasts briefly and, to be honest, is not all that different than starting Kindergarten.