Granny's Guide to understanding infant sleep

By Yvette O'Dowd

Your baby is not going to sleep through the night and that’s because they aren’t supposed to!

It's a hard fact to process in a society which values infant sleep and makes parents feel they have failed when their babies continue to wake in the night. But you can no more train a baby to sleep all night than you can train them to walk or ride a bike. It is developmentally normal for babies to repeatedly wake at night to breastfeed and to need parental contact and support to return to sleep.

By the time babies are 3 months old, some (but not all) begin to start settling By the time they are 5 months old, half of them may have started to sleep for an eight-hour stretch on some nights. Generally, though, babies do not sleep all night, every night, until they are more than a year old. One study investigating infant sleep duration found that 27% of babies had not regularly slept from 10pm to 6am by the age of 1 year. 13% of babies had not regularly slept through for 5 hours or more by the age of 1 year

Research using infrared video recording has provided evidence that, although sleep periods lengthen with age, infants continued to wake up during the night during the first year of life. Researchers used video and parental questionnaire data to examine one hundred infants’ sleep patterns at 5 weeks and 3 months of age. They found that a quarter of infants woke and resettled themselves at night, most often without parental awareness.

Circadian rhythm and the newborn human

It is normal and natural then for your newborn to have no discernible day/night pattern to feeding and sleeping. They lack the hormonal control to establish one. And it is not something they can be taught, no matter how much parents try and self-styled "sleep trainers" promise. Sleep duration is not a learned behaviour.

Breastfeeding is a relationship between a baby and their mother. But it is also a relationship between a baby and the breasts. A complex system of hormones guides your baby in many ways which might surprise you.

Nighttime milk is different to daytime

Your baby is born without an independent circadian rhythm, the day/ night clock which regulates our sleep/wake cycle in sync with the sun. While the maternal body clock supports the infant in the womb, their own system only begins to function from around 3 months.

Melatonin, cortisol, body temperature, movement, blood pressure, digestion, and consolidated sleep are all part of the circadian rhythm. The newborn infant develops the components of circadian rhythm postnatally. A rhythm of cortisol develops at 8 weeks of age, melatonin and sleep efficiency develop at approximately 9 weeks, and body temperature rhythm and that of circadian genes develop at 11 weeks.

Cortisol is a hormone our bodies increase as the sun rises and our brains respond to light. It wakes us up and keeps us alert. Breastmilk levels of cortisol are higher in the morning than at night. This signals to your baby that it is time to wake up and start the day.

Morning levels are approximately 4 times higher than levels present in breast milk produced in the evening (around 6pm). And they are about twice as high as levels present in milk expressed during the night (Pundir et al 2017; Italianer et al 2020).

Melatonin is the hormone our body relies on to wind down for sleep at the end of the day, as the sun sets and darkness sets in. In breastmilk it begins to rise in the evening and peaks at midnight.

It is possible the infant brain is guided to develop their own circadian rhythm through natural cycles of these hormones. Researchers in China have documented dramatic changes across a 24-hour period.

They tested the breast milk of 98 lactating mothers, and compared milk melatonin levels at 3pm, 9pm., and 3am.

On average, melatonin levels at 9pm were nearly 3 times as high as melatonin levels at 3pm. And the breast milk pumped in the middle of the night? At 3am?That’s when melatonin concentrations were at their peak — nearly 10 times higher than melatonin levels in milk collected during the afternoon.”

Nighttime breastmilk is a bedtime drink

Tryptophan, an amino acid which helps us fall to sleep for the night, is found in breastmilk. Adults and children benefit from tryptophan in foods which help make us sleepy and breastfed babies are just the same. Tryptophan is also necessary to synthesise melatonin and serotonin. Ingestion of tryptophan in infancy leads to more serotonin development, creating the potential for life-long well-being.

“Tryptophan is a precursor to serotonin, a vital hormone for brain function and development. In early life, tryptophan ingestion leads to more serotonin receptor development (Hibberd, Brooke, Carter, Haug, & Harzer, 1981). Nighttime breastmilk also has amino acids that promote serotonin synthesis (Delgado, 2006; Goldman, 1983; Lien, 2003). Serotonin makes the brain work better, keeps one in a good mood, and helps with sleep-wake cycles (Somer, 2009). So it may be especially important for children to have evening or night breastmilk because it has tryptophan in it, for reasons beyond getting them to sleep.”

— University of Notre Dame early-childhood researcher, Darcia Narvaez, PhD

Nighttime breastfeeding matters

In the 20th century, feeding babies during the night was treated like a behavioural problem. An inconvenient habit needing to be stopped by parents refusing to attend to their infant’s feeding cues and signals. “Sleeping through the night” was seen as a desirable milestone.

It is surprising to discover that not only is breastfeeding through the night normal and natural but babies actually rely on those feeds for around 20% of their daily milk intake. continued next page...

Night time breastmilk is naturally higher in fat, important for growth and development. Denying babies the breastfeeds they need during the night might lead to low milk supply and poor weight gains. When babies are left to cry their cortisol levels increase and remain high even when they cease calling for their mother. Cortisol is also a stress hormone.

Night feeding is important for milk production

Not only are the hormones important for circadian rhythm different at night but the hormone prolactin which drives milk production is too. Prolactin peaks in the early morning hours around 2-5 a.m., while the lowest prolactin levels happen in the late afternoon to early evening. Just in time to be boosted by that cluster feeding. By morning, your breasts might feel fuller and you notice a higher volume of milk if you express, though this milk is lower in fat than it was 12 hours before.

Breast feeding helps babies and mothers return to sleep quickly.

Breastmilk contains a wonderful hormone called cholecystokinin (CCK). CCK induces sleepiness, both in the baby and the mother. When the baby sucks, CCK is released within the mother to help her rest and relax. While mothers sometimes describe breastfeeding as making them tired, what they are experiencing during a feed is sleepiness. This is why lying down to breastfeed and breastsleeping work so well to help mothers get the sleep they need. Mothers who breastfeed during the night get more overall sleep than formula feeding mothers, who can take up to an hour to fall back to sleep after getting up to prepare and give their baby a bottle.

Breastfeeding to sleep is a natural part of an infant's sleep behaviour. CCK release is caused by sucking and when food, especially fat, enters the stomach. There are actually two CCK peaks, one at the end of a feed, and the other higher peak between 30 and 60 minutes after the feed. This is why babies often wake after the first 40 minute cycle of sleep and return to the breast before having a longer sleep period.

Breastsleeping is nature's way of packaging all this so that mothers and babies maximise milk production and sleep during the dark hours. The baby feeds most frequently around sunset and in the hours mother and baby would naturally spend lying together in the night. Frequent removal of milk from the breast stimulates production and the baby takes nearly a quarter of their daily nourishment while the baby sleeps.

Nighttime breastfeeding helps suppress fertility and aids natural child spacing.

Raising a human infant takes dedicated care around the clock. Conceiving another pregnancy while still tending a dependent infant is risky for all involved. Babies born too close together compete with each other for care and put a high demand on the mother both physically and emotionally. So nature put some protective barriers in place against premature conception by suppressing fertility.

When an infant has unrestricted access to the breast day and night, a woman’s return to ovulation and menstruation typically occurs after her baby begins eating family foods in the second six months. Some families practise The Lactational Amenorrhea Method (LAM) for postpartum contraception. This is not infallible and mothers can conceive while exclusively breastfeeding.

Typical child spacing in humans is 3-4 years, allowing the infant to wean before a new pregnancy. Similar age gaps are also seen in gorillas and chimpanzees, who parent in communities like humans. Orang-utan mothers, who live solitary lives with their young, breastfeed each for around 8 years before they separate and she is ready to breed again.

Babies and breasts work together around the clock to maximise infant growth and brain development. Night waking is normal in the first years of life and nighttime breastfeeding helps babies AND mothers.

Being the parents of infants who wake often at night is demanding. If you have other children, paid work or study, chronic health issues or little practical support it can be overwhelming. If you feel like everyone else has babies who sleep all night, it might help to know that as many as 50% of parents admit to lying about how much sleep they get - to avoid judgement from others!

Yvette O’Dowd is not your typical grandmother! This mother of three and 'Granny' of three has been a breastfeeding counsellor since 1992. In 2014, Yvette established the Southern Natural Parenting Network, incorporating South Eastern Babywearing Group. With 11,000 members world-wide, the group supports parents interested in breastfeeding, babywearing, co-sleeping, baby-led weaning and modern cloth nappies and other aspects of gentle, natural parenting. www.facebook.com/SouthernNaturalParentingNetwork