Understanding the 4 Month Sleep Regression

How a four month old's sleep patterns begin to change.

Identifying the root issues behind baby’s sleep regression is the key to overcoming it.

As a new parent, you may be celebrating reaching the stage where your baby's sleep schedule is somewhat consistent, and if that's the case, you may not be familiar with the term 'sleep regression' yet. But it's important that you understand what the 4 month sleep regression is before it hits your home.

If you have been following the Babywise sleep method laid out in "On Becoming Babywise", then you're well aware it provides parents with resources that help most babies sleep through the night for 8-9 hours by 12 weeks old (regardless of whether they are formula or breastfed).

Unfortunately, shortly after many parents celebrate this newfound success, they find themselves confronted with a baby who, again, begins waking during the night. What went wrong?

It turns out we can blame this sleep disturbance squarely on baby’s age. Babies around four months old (or for some, three or even five months old) have unique sleep disturbances based on their development.

Welcome to the (very common) Four Month Sleep Regression.

A Typical Four Month Old Baby’s Sleep

On Becoming Babywise describes four month olds as beginning to extend their morning wake times and complete five feed-wake-sleep cycles throughout a typical day. This means that your four month old is likely taking three 1.5-2 hour naps with a possible catnap around dinnertime.

Whereas newborns quickly fall into a deep sleep and are often difficult to wake (even at feeding times) a four month old begins to develop more mature sleep patterns. Babies who are four months old start to mirror adult’s sleep cycles; moving from deep to light sleep and back again.

Although shorter than your typical sleep cycle, a baby’s 45 minute cycle means that he’ll wake slightly to reposition himself and may look for familiar helps to fall back into a deep sleep. When baby wakes more fully between cycles or is unable to return to sleep, a regression occurs.

Signs of the Four Month Sleep Regression

A regression is any loss of a previously acquired skill.

If your baby was sleeping soundly throughout the night, interruptions may be confusing, frustrating, and (of course) tiring.

Your four month old may be going through a sleep regression if:
● he is waking more often throughout the night
● is increasingly fussy overnight,
● is consistently waking early from naps
● is suddenly famished overnight

By the time your baby is four months, you likely have a rhythm to your days. You have a consistent schedule and can generally pinpoint how often baby eats, how long baby is awake for, and what her typical sleep patterns are.

Any interruption to your normal routines will stand out.

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Understanding the Roots of Baby Sleep Regression

While there are many factors that influence the four month sleep regression, several stand out as most-likely scenarios:

Baby Sleep Regression Root Issue #1:
Baby is Unable to Achieve Deep Sleep

Baby used to be primarily in a deep sleep throughout the night but as he matures he begins cycling from light to deep sleep. During periods of light sleep it is much easier for baby to fully arouse himself.

Be conscious of what external stimuli may be cuing baby to wake up before it’s time. During naps it may be as simple as too much sunlight entering the room. In the evening or early morning hours household noises may inadvertently cue baby that it’s time to wake.

If your four month old consistently wakes after a 45 minutes of sleep or every 1-2 hours overnight he is having trouble achieving a deep sleep.

Your Sleep Regression Solution: Carefully watch, and even take notes, on your baby’s sleep patterns for several days. Look for commonalities about when baby is waking and list possible reasons why. It’s likely that something simple such as a white noise maker or light-blocking curtains may make the difference for your little one returning to a deep sleep.

Baby Sleep Regression Root Issue #2:
Baby is Unable to Self-Soothe

During a sleep regression is when you’ll learn the most about what sleep assistance your baby relies on.

Nursing your baby to sleep, swaddling him at nighttime, using a pacifier, or putting baby to sleep in a swing are all various sleep helps you’re providing. While some of these are beneficial (such as swaddling), others can be detrimental to baby’s ability to self-soothe.

Just as you and I may wake several times in the course of a night, change positions, and fall back asleep, baby also needs to be learn this skill. If you find yourself needing to help baby return to sleep by reinserting a pacifier, consistently using a baby swing, or nursing baby until he’s completely asleep, baby is unable to effectively self-soothe.

Your Sleep Regression Solution: It’s time to assess what assistance you’re providing baby. Take a few nights and list what ways you help baby fall back to sleep. Continue providing those sleep aids for now but make note of each way you’re assisting.

As you begin to see patterns of what you’re doing, search for a natural transition from you providing baby help to baby learning to self-soothe. For example, if baby only falls back to sleep after the pacifier is inserted, consider letting baby fuss for a few minutes to see if he can reinsert his own pacifier. Consider putting extra pacifiers in the crib. Or try a WubbaNub Pacifier at night so baby has something bigger to grasp as he tries to insert his pacifier.

Baby Sleep Regression Root Issue #3:
Baby is Requiring More Calories Throughout the Day

While four months isn’t a typical age for a growth spurt, some babies wake up hungry. If your baby was consistently sleeping throughout the night without needing overnight feedings, a hungry baby may be a surprise.

Your Sleep Regression Solution: A hungry baby could just be the result of a day your schedule was different. On the following day, make sure baby is getting feeding consistently on his typical schedule and make note if the sleep disturbances continue.

If baby continues to wake up hungry overnight, your baby may be ready to start solid foods. Check with your pediatrician about beginning baby on solids to help him fill up throughout the day instead of reverting back to overnight feeding sessions.

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Baby Sleep Regression Root Issue #4:
Baby is Feeling Unwell

A four month old is at a prime age to begin teething. Sleep disturbances within this age range can often be explained by baby feeling unwell. Teething can cause pain, fever, and may even contribute to uncomfortable diaper rashes.

Your Sleep Regression Solution: If your baby is waking at night or nap and cries out in pain, he could be feeling unwell. Check baby’s temperature and look for signs of teeth, such as inflamed gums and increased drooling. Monitor baby closely and consult your pediatrician if you are concerned baby is unwell.

Overcoming the Four Month Sleep Regression

Perhaps none of these root issues address your scenario. Every baby is different and each parenting situation unique.

If your baby is struggling with the four month sleep regression, consider waiting. Some babies at this age become bothered, will wake up more than usual, and then will move past the sleep interruptions without needing interventions.

The best thing you can do is educate yourself on baby sleep regression while paying close attention to the individual needs and cues of your child. After all, no-one knows your child better than you as their parent.

For more information about four month olds and sleep, check out:
Isolating the Source of Your Baby’s Sleep Problem
The Waking-Early Nap Challenge
Teething and Maintaining Sleep Routines
Baby Sleep Transitions: When to Drop a Nap


Jess Wartinger

Jess Wartinger

Jess Wartinger resides in rural New York with her husband and five children. Formerly an early elementary teacher, Jess currently spends her time loving her kids and holding down the fort at home.


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