Why Soothe a Crying Baby?

Alright this one is a little bit more academic than my usual writing as it's my final essay for my Pediatric Sleep and Development Specialist training but I think many people will enjoy nerding out on this -

Why Soothe a Crying Baby?.

Infancy is a critical time of brain development, with a million neuronal connections happening every second. This significant season of growth for babies is optimized and shaped by the caregivers sensitivity, attunement, reliability and responsiveness to all of the baby's feelings and states - including and especially stress. A caregivers warm and attuned nurture of their babies stress helps foster a relationship of secure attachment, helping co-regulate the infant and optimally support their developing stress system, which is largely a right-brain architecture. An infant is unable to soothe themselves, as the complex cognitive and neurological structures needed for this process are not yet wired, so soothing a crying baby is the responsibility of the caregivers. Positive, tolerable and toxic stress all impact the developing brain in different ways, which this essay will analyse. We will also discuss how nurturing stress and fostering a secure attachment with a baby shapes their brains and buffers stress.

There are three main categories of stress: positive, tolerable and toxic. Positive stress is also called eustress, and is characterised by brief and mild stress responses to situations. These are things like nervousness before public speaking, a job interview or working hard at a new task or skill. It is the stress we have to normative-experiences and are enough to foster growth through challenges. Having a caring, responsive adult to help a child through this form of stress helps them recover.

Tolerable stress is characterized by exposure to non-normative situations that contain greater degrees of adversity or a threat than positive stress. Tolerable stress are events like the loss of a family member, an injury, serious illness, family breakdown or climate disasters. These can be tolerated in the context of being supported and comforted within a secure relationship. For babies this means that tolerable stress is buffered through the responsive and attuned nurture of a primary attachment figure. This helps babies develop adaptive coping mechanisms in a healthy way and learn to regulate emotional intensity and life’s hardship with resilience.

Toxic stress is the form that can have long lasting and harmful impacts on the developing neurobiology and attachment system of babies. It can result from frequent and prolonged activation of the body’s stress response system, without the regulating buffering and protection offered by a secure, present caregiver. Toxic stress is often associated with adverse childhood experiences (ACE). Repetitive and prolonged times of neglect due to family dysfunction, addiction, mental health or separation are some of the most common reasons babies experience toxic stress. In this sleep training context, I would also argue that non-responsive care during the night when a baby is dysregulated and needing co-regulation, is a form of neglect that has the potential to create toxic stress for the vulnerable infant brain. Infants who are not soothed, may register their environment and situation as unsafe and their stress response may continue to escalate into toxic stress. This prolonged dysregulation forms their developing brain to be hyper vigilant later in life and instead of resources going towards building optimal neural connections between the sub-cortical and cortical regions of the brain, their brains may put more effort into growing a larger amygdala than children who do not experience toxic stress.

Attachment theory, developed by John Bowlby in the 1950s, is defined as a neurobiological system that is hardwired into human infants and prompts them to attach with a primary caregiver to facilitate their survival. This is not only for physical survival but for emotional and psychological as well. Attachment research from the last 70 years confirms that early attachment has lifelong impacts on mental and physical health. The importance of a secure attachment relationship cannot be more important for the thriving of a child into adulthood.

Infancy is a critical and sensitive time of brain development, meaning that its growth is unmatched at any other stage of life and crucial connections are being formed to allow the infant to adapt to its environment while building internal working models of relationship to Self and others that will impact their lifelong connections and wellbeing. A secure attachment relationship is inextricably related to optimal brain development and infant mental health. As Allan N. Schore explains, there is a shared theoretical framework within the clinical sciences that recognises the importance of regulation (Schore, 2001). Ongoing interdisciplinary research is affirming that the regulation of affect (emotional states) is a central organizing principle of human development and motivation (Schore, 2001). A secure attachment is at its very basic a relationship of regulation and reliable psychosociobiological nurture. 

The right brain is dominant during infancy and is centrally involved in processing social-emotional information, facilitating attachment functions and regulating bodily and observable emotional states (affect). It also plays a critical role in controlling the vital functions that support an infant’s survival and allow them to cope with the positive, tolerable and toxic stress in active or passive ways (Schore, 2001). The development of these critical right brain regulatory functions is experience dependent and is embedded in the attachment relationship between the infant and primary caregiver (Schore, 2001). Negative or positive experiences shape the maturation of these brain structures and as Schore writes:

“This developmental psychoneurobiological model clearly suggests direct links between secure attachment, development of efficient right brain regulatory functions, and adaptive infant mental health, as well as between traumatic attachment, inefficient right brain regulatory function, and maladaptive infant mental health.” (Shore, 2001).

There is ample research, mostly in rat models, that during sensitive periods of development, the HPA axis is being impacted negatively by stressful situations such as prolonged separation, low maternal care and abusive care. Hyper-responsive ACTH and corticosteroid responses are elicited in the HPA axis of rats who are not supported with high-licking and grooming (high nurture equivalent behaviour for rodents) (Engel, Gunnar, 2020). Without a nurturing, present and responsive caregiver, their stress is not buffered and creates a-typical neurological development within the brain.

For infants, situations where their stress is not buffered by the support and protection of a secure attachment relationship, will create adaptations in their brains to help them cope - this can look like a hypervigilant HPA axis, as they need enhanced threat detection and reactivity to dangers they experience. Infants who have the regulatory safety of a secure attachment figure can borrow their caregivers brain to down-regulate their stress response. This is what is commonly called soothing. A parent or caregiver is soothing the infant's HPA axis and helping their autonomic nervous system go from a sympathetic to a parasympathetic state with their responsive and attuned care. Infant mental health is shaped by this process of reliable soothing. They also develop internal working models that are more positive and influence the quality of their relationships later in life. It is therefore always important to soothe a crying baby. Day AND night.

References 

Schore, A. N. (2001). Effects of a secure attachment relationship on right brain development, affect regulation, and infant mental health. Infant Mental Health Journal, 22(1-2), 7–66. https://doi.org/10.1002/1097-0355(200101/04)22:1<7::AID-

Melissa L. Engel, Megan R. Gunnar, Chapter Three - The development of stress reactivity and regulation during human development, Editor(s): Angela Clow, Nina Smyth,

International Review of Neurobiology, Academic Press, Volume 150, 2020, Pages 41-76, ISSN 0074-7742, ISBN 9780128167526,https://doi.org/10.1016/bs.irn.2019.11.003.