Written and reviewed by Susie Warner

About Susie

Susie is a university-qualified Child and Family Consultant specialising in paediatric sleep and feeding. With over 20 years of experience supporting babies and families, through both her businesses, Happy Baby Consultancy and Lil’Koee, Susie has spent her career helping parents navigate the often-overwhelming world of 21st century parenting. Susie’s focus, despite all the noise, has always been clear: supporting parents, simplifying information and empowering families to feel more confident navigating two of the most emotional parts of early parenthood: feeding and sleep. Susie has also undertaken paid content collaborations with LittleOak.

Baby sleep can come with a lot of questions, and often, even more conflicting answers. From understanding wake windows and the four-month sleep regression to white noise, sleeping through the night and recognising infant sleep cues, it can be a tricky space to navigate for parents. 

How long should my baby's wake windows be?

This is a very common questions as a result of a lot of conflicting information regarding what an “awake window” should be for babies under 2 years old. Every day when I talk to parents the one key aspect impacting their little ones sleep is the timing variable. 

“Sleep pressure” is a relatively new 21st-century phrase that has become common in parenting conversations. In essence, it can encourage parents to keep a baby awake for longer so they are tired enough to fall asleep easily.

However, this approach can be the reason a baby is not sleeping well. Innate sleep is biologically driven, and when a baby is kept awake beyond what their body can comfortably manage, they can become increasingly unsettled and difficult to settle.

As babies become tired, their ability to regulate themselves can change. If they are not given the opportunity to wind down and regulate before becoming overtired, parents may see catnapping, frequent overnight waking or early morning starts.

Rather than focusing solely on the clock, I encourage parents to consider how long their baby has slept and then adjust the next awake period accordingly.

The table below provides a general guide for adjusting awake windows throughout the first 24 months.

What are the most common baby sleep cues and signs of tiredness?

The universal tired cue I look for is staring.

When the brain begins to reduce the amount of sensory information it is processing from the environment, a baby may reduce their blinking and appear to stare into space. This is one of the earliest and most useful cues for parents to respond to.

Other individual tired cues can include:

• Yawning
• Pulling the ears
• Rubbing the eyes
• Becoming quieter or less engaged

As tiredness increases, you may begin to see red eyebrows, increased noise and eventually crying. At this stage, the balance may already have shifted towards a baby becoming increasingly difficult to settle, so learning your baby's early cues can be incredibly valuable.

When do babies start sleeping through the night?

There is no magic age when every baby suddenly starts sleeping through the night. This will vary from family to family. Biologically it is possible from 6-8 weeks onwards.

However, sleep is influenced by many factors, including a baby's feeding journey, their sleep environment, whether they have been given opportunities to develop biological sleep patterns from birth, or whether their daily routine supports their underlying sleep biology.

There is so much information available through social media and online parenting advice that it can sometimes distract parents from the basics of infant biology.

If a baby is still experiencing significant night waking after 12 months, I would encourage parents to seek support and look at what may be contributing to their sleep patterns.

What is the four month sleep regression, and why does it happen? 

A “sleep regression” is another relatively new term used to describe a sudden change in a baby's established sleep pattern. Parents may notice more frequent waking or that their baby appears to have stopped linking sleep cycles as they previously did.

From my experience working with infant sleep for more than 20 years, I believe it is important to look at what else has changed around this age rather than automatically assuming that a regression is inevitable.

At around four months, babies are going through significant developmental and biological changes. Their feeding needs, sleep requirements and awake periods can all shift.

I often encourage parents to go back to the basics: think tummy and timings.

Hunger is a powerful biological drive, and babies need adequate nutrition to support growth and development. Iron is also an important consideration during infancy. When iron stores drop around 4 months this also reduces oxygen saturation crossing the blood brain barrier. Their brain is in a major growth phase therefore, it can start signalling its struggling. When the messaging about solids was moved to 6 months we all of a sudden had a new “issue” around sleep.

Four months is also not the time to drop a nap. Babies are experiencing a significant growth and developmental period and still need plenty of day sleep.

When a baby's sleep pattern changes, I encourage parents to see it as communication that their biological needs may have shifted rather than simply accepting that they are going through a “regression.”

Should I comfort my baby every time they cry or fuss in their cot? 

Babies can be surprisingly noisy sleepers. During active sleep, they may move, grunt, make noises and even appear unsettled. If your baby's eyes are still closed, they may simply be transitioning between sleep cycles. Giving them a moment to see whether they can settle themselves can sometimes be helpful.

If the noise escalates, however, it is absolutely okay to go in and provide calm, supportive assistance while they remain in their sleep environment.

It's also important to consider why a baby is becoming unsettled.

Fussing can sometimes be associated with an awake period that has gone on too long. Watch closely for early tired cues, such as staring. Once you begin seeing signs such as red eyebrows and increasing noise, a baby may be become increasingly difficult to settle due to an adrenalin surge. Their hunger instinct will also win and stop a baby being able to settle. Always ensure bub has a full tummy and all their calories required for their weight have been consumed.

Is the "cry it out" method harmful to babies?

Ideally, I don't believe a baby should be placed in a situation where they are required to cry alone for an extended period of time in order to change sleep behaviours.

There are gentler approaches that can help parents change sleep patterns and behaviours without leaving a baby to cry for prolonged periods. They need to be shown they can do it so they can do it well.

I often say to parents: “I don't sleep train babies.” Babies don't need to be trained to sleep. Sleep is a biologically driven process that is fundamental to survival, growth and healthy development.

My approach is to teach parents how to establish positive sleep behaviours and create the best biologically supportive conditions through “Tummy and Timings” (Full tummy and not overtired by knowing how to adjust awake windows) for their baby to sleep well, both now and for their long-term neurological development.

Is it bad to feed or rock my baby to sleep? 

Feeding or rocking a baby to sleep isn't necessarily “bad”, but it can create an association where the baby begins to believe they need that external assistance in order to fall asleep.

Sleep itself is biological. We have internal cues that drive us towards sleep because achieving deep sleep is essential for human survival and development. Deep sleep cannot be achieved fully if external assistance (parental behavioural props) overrides a baby’s internal drive to switch off all external senses.  When a particular external stimulus becomes part of the sleep process every time, a baby may begin to wait for that stimulus rather than responding to their own sleep cues.

This can become frustrating for both parents and babies if the parent later decides they need to change the pattern. Therefore, it’s about understanding the ‘story or interaction’ a baby is learning about sleep and making sure that supports their biological ability to achieve it well.

Does white noise help babies sleep? 

As a paediatric sleep specialist, I do not recommend white noise.

Babies are biologically wired for sleep as it is an essential part of human survival and development. We are not biologically designed to require a machine to cue us to sleep.

One way to understand this is through our senses.

When we are awake, we are constantly processing sensory information, what we see, hear, taste, smell and feel. During deep sleep, the brain changes how it processes this information so that restorative and neurological sleep can occur. White noise stops auditory input from disengaging therefore leaving the brain in a more wakeful state.

A common example is why we need a smoke detector to wake us in the event of a house fire: during deep sleep, we do not respond to our environment in the same way we do when awake.

I therefore prefer babies to become accustomed to normal everyday household sounds rather than requiring a specific sound machine in order to go to sleep. When babies rouse because the white noise has been stopped or turned off, correlates to them staying in a light sleep state and therefore achieving less deep neurological sleep.  Removing white noise improves sleep hygiene and can also make life more flexible.

Do babies need blackout blinds or a dark room to sleep?

Darkness plays an important role in the body's sleep biology, which is one reason we naturally associate darkness with nighttime sleep. Darkness also helps produce our necessary sleep hormones such as melatonin.

I often recommend blackout blinds, particularly when working with early morning waking during summer. A darker room can also reduce sensory stimulation during naps.

However, I don't believe babies need to sleep in a completely dark room for every nap. I actually encourage parents to allow their baby to experience naps out and about from a young age. This helps keep sleep flexible and means parents don't feel they have to stay at home every time their baby needs to nap.

What are your best baby sleep tips for overwhelmed parents?

• Go back to the basics: Reach out to a source that focuses on understanding infant biology rather than adding more noise and complicated strategies.
• Don't follow every piece of external advice: Social media can provide an overwhelming amount of information. Your baby is communicating with you all the time, and learning to read their individual cues is incredibly valuable. 
• Don't overthink everything: We are, fundamentally, simple creatures. We need food, sleep and shelter. Sometimes the clues to what is wrong re actually found in those basic needs.
• Remember that sleep is biological: Sleep isn't an emotional experience or something a baby needs to be "trained" to do. It is a fundamental biological requirement. 
• Help your baby regulate: Babies need to regulate in order to sleep well. How much regulation they require will depend on how well their fundamental "tummy and timings" needs are met. 

Most importantly, remember that you don't need to have all the answers. If your baby's sleep isn't working well, take a step back, look at the basics and seek support when you need it.

Frequently asked questions

How do I know if my baby’s naps are the right length?

A baby should wake from their naps refreshed and ready to move on with their day. They should be able to last their age-appropriate adjusted awake window and have no issues settling themselves for their next sleep opportunity. It's good to keep in mind that a shorter nap will result in a shorter awake window compared to a longer nap - their awake window is not a fixed length of time. For example, if they sleep 30 mins they will need to nap or go down for their night sleep sooner than after a 1.5 hour nap.

How many naps should my baby have each day?

This is age-dependent, but I do find parents are dropping naps too soon, and many babies end up overtired at bedtime, resulting in false starts, frequent overnight wakes or very early starts the next morning. Sleep is hormone-based, so the saying "sleep promotes sleep" is more accurate than "extend awake windows as the day progresses to create sleep pressure". Sleep pressure is adrenalin that needs to be expelled! 

How do I move from three naps to two?

Slowly is the key!! At around 8.5/9 months, most babies are showing signs that they are ready to extend their awake windows to approximately 3 hours after a 1.5 hour morning and afternoon nap, which allows for the opportunity to drop that pesky 3rd nap. If you drop to 2 naps too soon, it's likely you will see a disruption in their settling ability as well as their overnight sleep. 

Is it okay to co-sleep or bed-share?

There are more sensory disruptions when babies co-sleep or bed-share, meaning there is usually more arousal between cycles and more support required to link cycles. This disrupts the production of serotonin and melatonin; therefore, from a quality of sleep perspective, I recommend that a baby has their own safe sleep space. This allows all sensory input systems to switch off, resulting in a much deeper quality sleep profile which has long-term benefits. 

Should I use a sleep training method, and which one?

I explain to many parents on a daily basis that babies do NOT need to be sleep trained. They do not need to be "trained" to do something that is biologically necessary for basic survival and neurological safety. If a baby is not sleeping well, it will be due to a component of the parent's story that the baby is saying isn't working for them. After a discussion, it's usually evident their baby is hungry, overtired from lack of day sleep, or the parent's behaviours do not support biological interpretation from the baby. ie the parent is using an external prop (dummy, rocking, feeding to sleep) that overrides a baby's internal innate sleep cues. Before choosing a "method", reach out for individual support. 

How do illness, teething and travel affect sleep?

Any disruption to a baby's daily routine will likely impact their sleep. In terms of illness and teething, it's about treating pain and any sickness symptoms as much as possible to minimise the disruption, but if sleep slips, it's about getting back on track as soon as possible so a change in any behaviours doesn't stick. I always say one night to create a habit and three to break it. Travel is about having fun, knowing disruption is inevitable, hanging in there as best as possible and then jumping straight back into their usual routine once home again.