Evolutionary biology and cross-cultural studies tell us that infant sleep doesn't have to be hard (once you know how)

Most human cultures don't pay a lot of attention to their babies' sleep

Most cultures of the global majority have not experienced the kind of infant sleep distress that is so common today in the West.

In the late 1980s I went out into the Australian desert and stayed for a week with a group of First Nations People. I was a young doctor working in an urban Aboriginal and Torres Strait Islander Community Health Service, at a time when I was starting to think about having children of my own.

Out there amidst the spinifex, babies were always close to a loving adult's body. Toddlers roamed under watchful eyes or were lugged around on the hips of an older child. I noticed how these little ones fell asleep whenever their sleep pressure was high during the day, without fuss. They dropped off easily, either at their mother’s breast or nodding off on someone’s shoulders or hip. No-one made any effort to stay quiet or to keep them asleep. They slept in someone's lap or were lain down on a mat or cloth within reach, as their families sat cross-legged in the shade of the ghost gums noisily conversing, laughing, calling out, working with their hands to prepare food or repair things or make cultural objects.

Babies and toddlers started the day with the rest of the camp as the sun rose, and settled to sleep with the grownups at night, unless they’d already dropped off. They received the breast frequently, whenever they became even the slightest bit upset, or whenever the mother thought she'd like to offer. They were constantly surrounded by the extraordinarily rich and diverse sensory experiences of the outdoor world and of life in the midst of a group of people and kids. It was unusual to hear a baby cry for long.

It seemed to me that sleep was easy for the First Peoples' babies and toddlers I encountered in this more traditional context because they were satiated with milk, and satiated with unbelievably rich and changing sensory nourishment. They lived in the midst of their community’s shared circadian rhythms, were dialled down most of the time, and slipped in and out of sleep when the sleep pressure was high enough. No-one paid much attention to an infant's sleep.

A child's development isn't negatively impacted by a lack of sleep routine or the carers' failure to 'teach' babies to sleep in cultures different to the West. The intergenerational impact of colonisation takes its toll in other terrible ways in countries which have been colonised by Western powers in the last few centuries, but the lack of focus on babies' sleep in traditional cultures does not cause sleep or developmental problems later in childhood. On the contrary, from an evolutionary and cross-cultural perspective, baby and toddler sleep has been like breathing or making stomach juices for most of humankind, not something you have to worry about.

I believe that it's our widespread cultural anxiety and rules about infant sleep in the West which make baby and toddler sleep much harder than it needs to be, and which may cause problems in a small number of more vulnerable families down the track.

Creating a new approach to infant sleep using evolutionary and cross-cultural lenses

I’ve spent many years thinking about how to make the lessons I've learnt from First Nations Peoples, cross-cultural studies and evolutionary biology relevant for families’ lives in Western societies, drawing on the best of contemporary science. As a generalist doctor who has worked with families in the clinic most of her professional life, I've been focused on how to translate research into a pragmatic infant sleep program that works in the real lives of 21st century families, even when they are surrounded by the dominant Western beliefs about sleep and infant sleep training.

When I presented an early version of The Possums Sleep Program at a conference in 2011, a colleague stood up and spoke to the delegates. She protested that "modern women need to return to paid work, so they can't sleep with their babies or feed them all night like !Kung Bushmen". I completely understood what my colleague meant. I too feel very protective towards contemporary new mothers, who are often socially isolated and burdened with excessively high levels of occupational fatigue.

But this health professional's concern was framed within 1950s' stereotypes about non-Western cultures. I hadn't mentioned the existing cross-cultural studies concerning the !Kung. Her concern was shaped by the belief, again originating in the 1950s and 1960s, that sleep training makes life easier for parents, which it mostly doesn't. She confused developmentally normal night waking with excessive night waking, which everyone did at the time.

Contrary to my colleague's beliefs, human sleep and human sleep architecture have evolved to be highly social, flexible and adaptive. Waking in the night is normal for Homo sapiens, whether we are caring for babies and toddlers or not. My colleague's conviction that a woman needs unbroken nights in order live well and perform cognitively also rested on another out-of-date belief, that breastfeeding and cosleeping make life harder for women. Now the science confirms that these evolutionarily-aligned practices make sleep easier.

We live in a time of staggering global challenge, caused by the Western world's belief in our right to exert control over and exploit the environment. This worldview has extended to the wilderness of a baby, a little human shaped by evolutionary biology to expect a certain set of conditions, both from the environment and from the humans around her. But she arrives into a health system whose infant care practices often don't match her biological expectations.

This evolutionary mismatch makes life much harder than it needs to be for her, and therefore for her family. Social isolation is a serious problem for primary carers of babies and toddlers, and needs to be addressed - but trying to change the biology of the little one's sleep is not the answer.

I have the view that before all else, parents need to enjoy their babies and toddlers. This is best for the little one's developing brain, and best for parental wellbeing. We need to find new ways to support families who are challenged by their baby's or toddler's sleep, for the sake of our shared human future on this small blue planet.

That's what I've aimed to do with The Possums Sleep Program. It really is possible for your little one's sleep to become easy (or at least to become more manageable). Often we have to repair excessive night waking first. It just takes trying out some new things, experimenting, and seeing what you think.

Recommended resources

What is sensory motor nourishment and why does it help with baby sleep?

Filling your baby's sensory tank

Why baby wearing makes life easier (not harder)

What your baby needs for best possible motor development

The holistic NDC or Possums 8-step approach to supporting baby's motor development

The NDC evolutionary perspective on positional plagiocephaly, motor development and sleep

Acknowledgement

I acknowledge the traditional owners of the land upon which I've created The Possums Baby and Toddler Sleep Program here in south-east Queensland, the Yuggera and Turrbal peoples, whose babies and toddlers have been sleeping easily and soundly in the midst of their families, close to loving adults’ bodies, for anywhere up to 65,000 years.

Selected research

Crittenden AN, Samson DR, Herlosky KN. Infant co-sleeping patterns and maternal sleep quality among Hadza hunter-gatherers. Sleep Health. 2018;4(6):527-534.

Hamilton A. Nature and Nurture: Aboriginal Childrearing in North-Central Arnhem Land. Canberra: AIAS; 1981.

Rudzik AEF, Ball HL. Biologically normal sleep in the mother-infant dyad. American Journal of Human Biology. 2021;33(5):e23589

Samson DR. The human sleep paradox: the unexpected sleeping habits of Homo sapiens. Annual Review of Anthropology. 2021;50:259-274.

SNAICC. Growing up our way: practices matrix. North Fitzroy, Melbourne: Secretariat of National Aboriginal and Islander Child Care, 2011.