Should Your Baby be Sleeping Through the Night?

I will admit from the start that this topic is a HUGE trigger for me, personally. And it has become a very big pet peeve. Does anyone else relate? When I had babies and would hang out with other parents of babies, the topic would ALWAYS come up. “How are the babies sleeping?” or “Is your baby sleeping through the night, yet?”

I didn’t want to be asked, and would go to some trouble to get out of the conversation, because I had a sense that I should be ashamed of my answer. My babies did not sleep through the night. 

 

Are Babies Supposed to Sleep Through the Night? 

Since then, I’ve come to work at Breastfeeding Success, and have learned so much more about the biology of infant and newborn sleep and especially how that relates to breastfeeding. What I’ve learned is that babies are not biologically designed to sleep “through the night”, and that there are good reasons for this. 

 

Babies Have Different Sleep Cycles

Adult sleep cycles vary from 90-120 minutes in length. This doesn’t mean you only sleep for that long. It just means you go through each of the sleep stages during this time. So you spend some time in light/active sleep, deep sleep, and REM. These are all important for your health, and they happen many times during the night. So an adult might go through 4-6 of these cycles during a normal night’s sleep. 

Babies spend a lot more time in REM sleep, and they also have shorter sleep cycles of 45-50 minutes. This generally means they don’t sleep as deeply, and they wake more often. 

 

Babies Do Not Have Circadian Rhythms

Circadian rhythms are how our body systems adjust to light and dark. There are very physiological changes that happen in the human body based on daylight and dark. Body temperatures change, appetite and digestion are affected, hormone release is regulated by this, and so are sleep patterns. This makes sense from an evolutionary perspective. Humans can’t see in the dark. We are not nocturnal animals, so night is the best time to get safe, quiet, still, and rest. Our body systems slow down and we make hormones to help us fall asleep and recover and rest. 

Newborns are just starting to be exposed to sunlight. While in the womb, it was all dark all the time, so they didn’t develop these physical rhythms. They had a constant body temperature, a steady stream of oxygen and nutrients from their mothers’ body, and their parents’ movements and heart beat to lull them to sleep. A lot of times, pregnant folks notice that their babies are less active when they are up and moving, and tend to get more active as soon as they try to lay down to fall asleep! 

You might notice that your newborn seems to have their days and nights switched. This is because they developed that habit in the womb. Once born, newborns start the process of developing circadian rhythms, but this can take time. 

It’s a good idea to let babies be exposed to natural daylight and dark as much as possible to help them develop. Keep the windows open and go outside during the day. Keep lights off or very low at night.

 

Babies Have Tiny Bellies

Babies are born with bellies about the size of a marble. It will grow quickly over the first few weeks, but even then it’s small. That means it doesn’t take a lot of milk to fill it, but it also empties quickly. It’s critical for their growth and development to eat often. It’s also how your milk supply develops. At first there is only a small amount, about the amount needed to fill a marble-sized belly! Over time, as the baby’s belly grows, the milk supply will need to grow with it. Your milk supply grows by having a baby at the breast a lot. This is how your body knows to keep making more milk. This means you will need to feed your baby day and night. As the baby’s belly grows, they will get more milk at each feeding and will gradually be able to lengthen the amount of time between feedings. But be patient, because only your baby can know whether they need to eat or not. Some are very fast eaters, others are slower. Some milk has a higher fat or calorie content, while some has less which will mean a baby needs to eat more often. 

 

What Does “Sleeping Through the Night” Mean? 

An “official” definition of “sleeping through the night” doesn’t seem to exist. However, experts do seem to be in agreement about what it DOES NOT mean. It does not mean sleeping from 7pm-7am without waking. Most experts describe a normal longest stretch of sleep at night as being anywhere from 4-8 hours. This depends on the baby’s age, and it’s generally agreed that these longer stretches of uninterrupted sleep can start as early as four months for breastfed babies. A formula fed baby might sleep longer stretches earlier. What a parent might expect is that their four month old might sleep four or six hours at a time, and that it will start to get longer and longer as the baby grows. You might also expect that at around six months of age, you’ll see some changes. Sometimes babies start waking more often at big developmental milestones. At six months, a lot of babies go through “separation anxiety”. This means they might need some extra reassurance during the night, and that can be totally normal and temporary. At any point, a baby might get sick or start crawling or climbing or walking or getting a new tooth! These things can also affect how a baby sleeps. It’s so important to remember that there is not one right way for your baby to sleep, and they are supposed to change. If your baby doesn’t meet some arbitrary ideal, it does not mean there is something wrong or that you are doing something wrong. Sleep parenting takes some patience and flexibility, and trust that your baby is normal, you are doing a great job, and things will work out. If you want some extra reassurance and support, we have a fantastic class about infant sleep for parents who want to know more. 

 

How Sleep Works – Sleep Phases and Stages | NHLBI, NIH

Circadian Rhythms | National Institute of General Medical Sciences

Infant sleep and its relation with cognition and growth: a narrative review – PMC

Getting your baby to sleep through the night: The good (and maybe not-so-good) news – Harvard Health