In the animal kingdom, certain behaviors are instinctual and natural. Polar bears thrive in the cold of the Arctic, sloths move slowly through the trees, and orcas live in the ocean. Similarly, human babies are biologically designed to sleep close to their mothers. This isn’t a matter of opinion—it’s simply a fact based on biology and human evolution.
Over time, however, cultural expectations have led to a shift in how infant sleep is approached, particularly in Western societies. These expectations, shaped by societal norms rather than the needs of babies, have distanced mothers from their infants during sleep. While babies can survive sleeping separately, research shows that thriving—physically, emotionally, and developmentally—often comes from shared sleep with their mothers.
Why Babies Need to Sleep Close to Their Mothers
Human babies are naturally wired to be close to their mothers, especially during sleep. This isn’t just a preference; it’s deeply rooted in biology. Babies are born with an instinctual need for proximity to their mothers, which supports critical physiological functions like regulating their breathing, heart rate, and body temperature.
Professor James McKenna, an expert from the Mother-Baby Behavioral Sleep Laboratory at the University of Notre Dame, has spent years studying the connection between co-sleeping and breastfeeding. His research shows that breastfeeding and co-sleeping evolved together as essential behaviors. When babies sleep close to their mothers, breastfeeding acts as a hidden regulator, ensuring that both mother and baby stay in sync throughout the night.
For infants, the need for closeness goes beyond simple comfort. Anthropologist Sarah Blaffer Hrdy has emphasized that, for species like humans, the mother provides a critical environment even after birth. This idea is supported by the concept of “exterogestation”—the understanding that human babies are born nine months early in terms of development and continue to gestate externally, meaning they need constant physical contact and care during their first months of life. As such, a mother’s presence during sleep is vital for her baby’s continued development.
How Sleeping Together Benefits Both Moms and Babies
One of the major advantages of shared sleep is its positive impact on breastfeeding. Studies have shown that when babies sleep in the same room or bed with their mothers, they breastfeed more frequently, which helps maintain a strong breastfeeding relationship.
Dr. Helen Ball’s research reveals that babies who sleep closer to their mothers nurse up to 70% more at night than those who sleep farther away. Another study from Brazil found that bedsharing at three months helped prevent early weaning, with 75% of bedsharing infants still breastfeeding at twelve months compared to 52% of those who slept separately.
Better Rest for Moms
Despite the common belief that co-sleeping leads to more nighttime interruptions, research shows that mothers who share sleep with their babies tend to get more rest. Breastfeeding mothers, in particular, experience lighter awakenings and fall back to sleep more quickly when bedsharing, leading to longer, more restorative sleep. A study by Dr. Kathleen Kendall-Tackett found that breastfeeding mothers reported more energy, better health, and lower levels of depression compared to mothers who used formula or mixed feeding methods. This is because co-sleeping allows mothers to meet their baby’s needs without fully waking up, leading to more overall rest.
Supporting Healthy Development
When babies sleep close to their mothers, they benefit from a stronger sense of security, which plays a crucial role in their brain development. Skin-to-skin contact, frequent breastfeeding, and the warmth of their mother’s presence provide essential sensory inputs that help to stimulate their rapidly developing brain. Research shows that babies who experience regular physical contact and proximity to their mothers tend to have better cognitive and emotional outcomes as they grow.
How Sleep Practices Have Changed Over Time
Historically, sleeping close to babies was the norm in most cultures around the world. For centuries, parents shared sleeping spaces with their infants to ensure their safety and meet their needs more easily, whether through breastfeeding or simply providing comfort. Different cultures have their own versions of co-sleeping, ranging from sleeping together in the same bed to placing babies in close proximity using hammocks or baskets. The common factor was that babies were always within arm’s reach of their caregivers.
However, around 500 years ago, things began to change in Western societies. Religious and cultural shifts played a significant role in this transformation. In Europe, church doctrines instructed parents to separate infants from adults during sleep to prevent accidental suffocation. At the same time, growing affluence made separate bedrooms more common, and the rise of individualism encouraged parents to foster independence in their children from an early age. Freudian psychology also reinforced the belief that children should not sleep in the same bed as their parents to protect them from exposure to adult sexuality.
By the 20th century, sleep training methods like the “cry it out” approach became popular, with the idea that babies needed to learn to sleep independently. This shift in sleep practices created the modern image of nurseries and solitary sleep, which many parents now view as a measure of good parenting.
Addressing Concerns and Criticisms About Co-Sleeping
While co-sleeping has been practiced for generations across many cultures, it has also faced criticism, especially in recent decades. One of the primary concerns raised by medical professionals is the risk of Sudden Infant Death Syndrome (SIDS) and accidental suffocation when babies sleep in the same bed as their parents. These safety concerns have led to recommendations against bedsharing from organizations like the American Academy of Pediatrics, which suggests that the safest place for a baby to sleep is in a separate crib in the same room.
However, it’s important to note that many of the risks associated with bedsharing can be minimized by following safe co-sleeping practices. Dr. Nils Bergman, a leading advocate for skin-to-skin contact between mother and baby, points out that the real danger lies not in the presence of the mother, but in environmental factors like smoking, alcohol, and unsafe bedding. By eliminating these risks, co-sleeping can be a safe and beneficial choice for many families.
Critics also argue that bedsharing may create dependence, making it harder for children to transition to independent sleep. However, research shows that while co-sleeping children may transition to solitary sleep a little later, they often exhibit greater independence and self-reliance during the day. For parents who are concerned about safety, co-sleeping within the same room without bedsharing is another option that offers many of the same benefits while reducing risk.
Embracing What’s Best for Babies and Parents
The decision about where babies should sleep is deeply personal, but it’s clear that sleeping close to their mothers offers significant benefits for both baby and parent. From promoting breastfeeding to improving sleep quality and supporting healthy brain development, co-sleeping aligns with the natural needs of human infants. While there are valid concerns around safety, following guidelines for safe sleep can help mitigate the risks, allowing families to make informed decisions that work best for them.
In a world where parenting advice can often feel overwhelming and contradictory, it’s important to trust biology and the evidence that supports the advantages of co-sleeping. By embracing practices that align with how babies are designed to thrive, parents can foster stronger connections with their children and ensure their development is supported in the earliest and most critical stages of life.
