“Is your baby sleeping through yet?”
It is one of those questions people seem to start asking surprisingly early. Sometimes it is just conversation, but when you are the one getting up several times a night, it can land differently. If other babies in your antenatal group are apparently sleeping from seven until seven while yours still wakes at midnight, two, four and five-thirty, it is very easy to start wondering whether something has gone wrong.
The difficulty is that “sleeping through the night” does not have one agreed meaning, and the way we use the phrase in everyday conversation is often very different from the way it has been used in research. A parent may hear it and imagine ten or twelve uninterrupted hours. A researcher may be talking about six. Your friend may say her baby sleeps through because they feed once at 5 a.m. and both go straight back to sleep. Someone else may mean that their baby no longer needs them during the night, even though the baby almost certainly still moves between different stages of sleep and has brief periods of waking.
So before deciding when babies should sleep through the night, it helps to work out what we are actually asking.
What does “sleeping through” actually mean?
In sleep research, several different definitions have been used. One influential longitudinal study followed 388 babies and looked at whether they could sleep for six or eight consecutive hours at six and twelve months. These were the researchers’ definitions of sleeping through the night; they were not asking whether the babies slept from bedtime until morning without waking.¹
And quite a lot of healthy babies did not meet even those definitions. At six months, 37.6% had not yet slept for six uninterrupted hours and 57.0% had not slept for eight. At twelve months, 27.9% still did not regularly manage six hours and 43.4% did not manage eight.¹ That is worth sitting with for a moment, particularly if you have been given the impression that a six-month-old who still wakes at night is unusual.
There is another complication too. Sleeping through is not necessarily a milestone that a baby reaches once and then keeps forever. A baby may give you an astonishing eight-hour stretch one night and wake three times the next. They may sleep beautifully for several weeks and then start waking again when feeding changes, development accelerates, they are ill, their daytime sleep changes or life simply becomes more interesting. BASIS, the infant sleep information source developed from research at Durham University, makes this point explicitly: many babies who have already “slept through” later return to waking at night.²
If you have ever announced triumphantly that your baby has finally started sleeping through and then immediately had the worst night in three months, you will already be familiar with this phenomenon.
Night waking is part of normal infant sleep
Babies do not sleep like small adults. Their sleep changes enormously during the first years of life, and there is also striking variation between babies of exactly the same age.
A systematic review of observational studies examining normal sleep from infancy through childhood found wide variation not only in total sleep duration but also in night waking, nap patterns and the longest period of continuous sleep.³ Some babies consolidate their night sleep relatively early; others take considerably longer. Even beyond the first birthday, waking during the night can remain part of normal sleep.
This does not mean that every pattern of night waking must simply be endured or that frequent waking can never have a medical or practical cause worth investigating. If something has changed suddenly, your baby seems uncomfortable or unwell, breathing concerns you, feeding or growth is an issue, or your instincts tell you that something is not right, that deserves attention.
But waking itself is not evidence that your baby has failed to learn how to sleep.
What about babies who really do sleep twelve hours?
They exist. I have worked with families whose babies naturally began sleeping very long stretches surprisingly early, and I have worked with families whose babies were still waking several times a night much later. One of the easiest traps in baby sleep is to look at those two babies and assume that the difference must have been created by what their parents did.
Sometimes what we do matters, of course. Sleep timing, daytime sleep, light exposure, feeding, activity, the sleep environment and the way a baby is helped back to sleep can all influence how nights unfold. If a current arrangement is exhausting everyone, there may be useful things to explore.
But babies also arrive with different temperaments, different sensitivities and different patterns of sleep regulation. The baby who sleeps a long uninterrupted stretch is not necessarily the product of superior sleep parenting, just as the baby who wakes frequently is not evidence that somebody has created “bad habits”.
This is particularly important when parents compare babies. You usually know everything about your own difficult night and almost nothing about somebody else’s. “She sleeps through” may turn out to mean that she wakes at five for a feed. It may mean that she wakes briefly and settles again without signalling. It may genuinely mean twelve uninterrupted hours. All of those babies can be normal.
Does a baby need to sleep through for healthy development?
This is where the research is reassuring. In the longitudinal study I mentioned earlier, researchers did not find an association between failing to sleep for six or eight uninterrupted hours and poorer mental or psychomotor development. Babies who were not sleeping through at six or twelve months were not showing worse developmental outcomes simply because their sleep remained interrupted.¹
That does not mean sleep is unimportant. Of course it is. Babies need adequate sleep across the day and night, and chronic sleep disruption can matter for the whole family. But total sleep and an uninterrupted eight-hour block are not the same thing. A baby can wake, feed, receive some help and return to sleep while still getting perfectly adequate sleep overall.
The study also found that babies who were breastfeeding were less likely to meet the six- and eight-hour uninterrupted sleep definitions.¹ That should not be particularly surprising. Feeding remains one of the reasons babies wake and seek you during infancy, and human milk is digested relatively quickly. It certainly does not mean that breastfeeding is causing a sleep disorder.
But I am exhausted
This matters just as much as understanding what is normal. There is a strange leap that sometimes happens in conversations about biologically normal infant sleep: once we establish that waking is normal, it can sound as though the parent is therefore expected to be perfectly fine with waking six times a night for the foreseeable future. Those are two completely different questions.
Your baby’s sleep can be developmentally normal and still be incredibly hard for you.
If you are barely functioning, we do not have to turn your baby into a problem before we are allowed to look for ways to make nights easier. We can look at the whole picture: how much your baby sleeps during the day, when sleep happens, whether there are long awake periods at night, how feeding is going, how quickly your baby returns to sleep, whether somebody else can help, and whether the way nights are currently organised is sustainable for your family.
Sometimes relatively small changes make nights noticeably easier. Sometimes the biggest change is not in the number of wakings but in how much work each waking requires. And sometimes what you need most urgently is not a new settling technique for your baby but a realistic way for you to get more sleep. Normal does not automatically mean easy.
So when should my baby sleep through the night?
There really is no age at which every healthy baby should suddenly begin sleeping from bedtime until morning without needing you. Sleep generally becomes more consolidated as babies grow, and longer stretches become more common across the first year. BASIS notes that by around three months some babies begin sleeping through a night-time feed and may manage a stretch of about five hours; by around five months, about half may have slept an eight-hour stretch on at least some nights. But sleeping all night, every night is a different matter, and many babies do not do that until much closer to their first birthday. Some continue waking beyond it.²
So if your baby is six months, nine months or twelve months old and still wakes at night, the waking alone does not tell me that there is a problem. I would want to know much more: what the whole twenty-four hours looks like, how often your baby wakes, how long they remain awake, what they need from you, whether this pattern has changed, and perhaps most importantly, how it is affecting you. That gives us much more useful information than whether we can tick a box marked sleeping through.
References
- Pennestri MH, Laganière C, Bouvette-Turcot AA, et al. (2018). Uninterrupted infant sleep, development, and maternal mood. Pediatrics, 142(6), e20174330.
- BASIS – Baby Sleep Information Source. Normal Infant Sleep. Durham University.
- Galland BC, Taylor BJ, Elder DE, Herbison P. (2012). Normal sleep patterns in infants and children: a systematic review of observational studies. Sleep Medicine Reviews, 16(3), 213–222.