Co-Sleeping + Biological Needs of Our Babies
One of the earliest pressures new mothers encounter is the suggestion to let their baby “cry it out”, as a way of teaching independence or ensuring better sleep for the family. However, both clinical research and maternal instinct demonstrate that babies are not designed to cry in isolation.
Their cries are a biological signal, designed evolutionary hold their caregiver close.
Infant Stress Response
When an infant cries, their nervous system enters a state of distress.
Studies show that being left alone without comfort elevates cortisol levels, a stress hormone that influences brain development and long-term stress regulation. Research published in Early Human Development found that babies left to cry without response continue to experience high cortisol even after they have stopped vocalising, a physiological sign that their body has entered resignation, not calm (Middlemiss et al., 2012).
This is often mistaken for “self-soothing,” yet newborns and young infants are not neurologically capable of self-regulation.
’Quiet’ is in fact a stress response that has been silenced, not resolved.
Co-Regulation
When a parent responds, by holding, feeding, or simply offering presence, the child’s stress response is nurtured.
Their nervous system settles through co-regulation, where the parent’s steadying presence communicates safety.
Over time, these repeated experiences build the neural architecture for resilience, emotional regulation, and secure attachment.
Mary Ainsworth’s pioneering attachment research showed that infants whose cries were met with consistent responsiveness grew into children who were more independent and socially confident. Dependence in infancy is the foundation for healthy independence later.
Co-Sleeping
Co-sleeping, when practiced safely, extends this principle of responsiveness into the night. Human infants are born neurologically immature compared to other mammals and rely on proximity to their caregivers to regulate their breathing, heart rate, and temperature.
A landmark study by McKenna and Mosko (1994) demonstrated that when infants slept in close contact with their mothers, their sleep cycles became more synchronised, their arousal patterns more protective against SIDS, and breastfeeding frequency more easily sustained.
Rather than disrupting rest, this closeness creates physiological stability for the baby while allowing the mother to respond instinctively with minimal disturbance to her own sleep.
Attachment & The Developing Brain
Attachment theory continues to affirm that a baby’s sense of security comes not from being pushed into early separation, but from being consistently reassured that their needs will be met.
Neuroscientist Allan Schore’s work on early brain development emphasises that repeated moments of attuned care shape the infant’s right brain; the core of emotional regulation and resilience.
When we respond to cries, when we hold our babies through the night, we are shaping their neural pathways for trust and safety.
The cultural pressure to train babies into silence through “cry it out” methods misunderstands what true self-regulation is.
Regulation is learned in relationship; our baby’s nervous system develops stability through thousands of cycles of co-regulation with a responsive caregiver.
Only through this repeated pattern does the child gradually develop the capacity to soothe themselves later on.
Ignoring your babies cries may eventually create silence, but it is a silence rooted from withdrawal and disassociation, not of peace.
Responding to our babies’ cries and keeping them close during the night is not indulgence, weakness, or creating “bad habits.” It is deeply aligned with biology, supported by decades of research, and essential for long-term wellbeing.
It nurtures trust, protects developing brain development, and gives children the secure foundation they need to one day step into the world with confidence.
Presence, not distance, is what builds resilience.
With Gratitude,
Alicia (BHSc Clinical Nutrition)
