Why does My 4 Month Baby Cry in His Sleep? Sleep Guide

Understanding Why Your 4-Month-Old Baby Cries in Their Sleep

Babies crying in their sleep is a common concern for many parents.

Especially when it comes to a 4-month-old baby, it can be a bit of a mystery, causing many sleepless nights and worrying days.

But fear not, as it’s a relatively common occurrence and can often be addressed with the right knowledge and approach.

Sleep Cycles of a 4-Month-Old Baby

To comprehend why your baby might be crying in their sleep, it’s crucial to understand their sleep cycle.

A baby’s sleep cycle is much shorter than that of an adult.

It usually lasts about 50 minutes for newborns and extends to about 1-2 hours by the time they’re a year old.

A full sleep cycle includes both lighter (REM or rapid eye movement) and deeper (non-REM) stages of sleep.

During the transition between these stages, or at the end of a sleep cycle, babies partially awaken and may cry or fuss.

Reasons Your 4-Month-Old Baby Cries in Sleep

Sleep Regression

At around 4 months, babies undergo a significant developmental milestone known as sleep regression.

During this phase, your baby’s sleep pattern changes, becoming more like an adult’s.

Their sleep is divided into more, and longer cycles of light and deep sleep.

This can lead to more frequent awakenings and a greater likelihood of crying.

Dreams and Nightmares

While it’s tough to confirm if babies dream, rapid eye movement (REM) sleep, the stage associated with dreaming in adults, makes up a significant portion of a baby’s sleep.

So, it’s possible that dreams or even nightmares could cause your baby to cry in their sleep.

Growth Spurts and Discomfort

Growth spurts often coincide with increased fussiness, and these can occur around the 4-month mark.

Your baby may be experiencing growing pains or general discomfort.

This physical discomfort can interrupt their sleep, leading to crying.

Hunger or Thirst

Babies, especially those going through growth spurts, may need nighttime feeds.

If your baby is used to eating or drinking during the night, they may cry in their sleep out of hunger or thirst.


Around this age, some babies may start teething.

The discomfort from the gums can cause your baby to wake up crying.

How To Soothe a Crying Baby

Maintaining a Consistent Sleep Schedule

Consistency can help your baby understand when it’s time to sleep.

Establish a regular bedtime routine that includes calming activities such as a warm bath, a gentle massage, or reading a book.

Responding to Their Cries

You know your baby best.

Some babies are comforted by a gentle pat or some soft words, while others might need to be picked up and cuddled.

However, try to keep nighttime interactions calm and quiet, so your baby understands it’s not time to play.

Feeding and Changing Diapers

Ensure your baby is well-fed before bedtime and that their diaper is clean and dry.

A hungry baby or a wet diaper can cause discomfort leading to sleep disruptions.

Creating a Sleep-friendly Environment

Ensure the sleep environment is comfortable, quiet, and dark.

Consider using a white noise machine to mask any potential disruptive sounds.

The temperature should be kept at a comfortable level, as a room that’s too hot or too cold can disrupt sleep.

While it might be distressing to hear your baby cry during their sleep, remember it’s usually a normal part of their development.

If the crying continues excessively or you notice other symptoms such as fever, loss of appetite, or changes in behavior, it’s advisable to consult a healthcare provider to rule out any potential medical issues.

Remember, each baby is unique and what works for one might not work for another.

Patience, observation, and a process of trial and error will go a long way in solving the mystery of why your 4-month-old baby is crying in their sleep.

Sleeping Positions and Baby Safety

A baby’s sleeping position can also affect their sleep quality.

The American Academy of Pediatrics recommends that babies should always be placed on their backs to sleep.

This position reduces the risk of sudden infant death syndrome (SIDS) and can help your baby sleep more soundly.

An overtired baby can also have trouble sleeping and might cry.

Make sure your baby is getting enough sleep during the day and isn’t staying awake for too long.

External Factors

Consider external factors that may be affecting your baby’s sleep.

This can include loud noises, a room that’s too light, or even an uncomfortable crib or mattress.

A baby monitor can help you keep an eye (and ear) on your baby’s sleep habits and environment.

If your baby tends to cry at the same time every night, they might be experiencing what’s known as the “witching hour.”

This is a period, usually in late afternoon or evening, when a baby can be more fussy or cry more.


By around 4 to 6 months, many babies start learning to self-soothe.

This means they can calm themselves down and go back to sleep without your help.

If you always rush in at the first whimper, your baby may not learn to self-soothe.

If your baby’s cries escalate or if they seem in distress, definitely go to them.

But if they’re just fussing, give them a few minutes to see if they settle back down on their own.


Pacifiers can be a useful tool for helping babies soothe themselves back to sleep.

However, they should never be used as a replacement for meals, and should be used sparingly to avoid dependency.


Swaddling can mimic the warm, cosy feeling of the womb, and can soothe a fussy baby.

However, make sure your baby isn’t swaddled too tight, as this can cause discomfort.

While these tips can help you manage your baby’s sleep crying, always trust your instincts.

You know your baby best, and if something doesn’t feel right, it’s worth getting it checked out.

Remember, you’re not alone in this.

Many parents have faced the same struggles and worries.

Don’t hesitate to reach out to other parents, your pediatrician, or a sleep consultant for support.

Frequently Asked Questions

Q1: My baby seems to be having nightmares. Is this possible at 4 months old?

A: Although it’s difficult to know for sure since babies can’t tell us what they’re dreaming about, most experts believe that babies start having dreams and possibly nightmares at around 6 months old. However, if your baby seems particularly distressed during sleep, it’s worth bringing it up with your pediatrician.

Q2: Should I always comfort my baby when they cry in their sleep?

A: If your baby is crying softly or whimpering in their sleep, it’s generally recommended to wait a few minutes to see if they settle back down on their own. If the crying becomes more intense or lasts longer than a few minutes, it might be a sign that your baby needs comfort or has a need that should be addressed (like a diaper change).

Q3: How can I differentiate between normal sleep crying and a sign of illness?

A: Normal sleep crying typically resolves on its own and doesn’t wake the baby completely. If your baby’s sleep crying is accompanied by other signs of illness, such as fever, vomiting, lack of appetite, or lethargy, or if it’s unusually intense or prolonged, it’s a good idea to consult with your pediatrician.

Q4: Can sleep crying be a sign of teething?

A: Yes, sleep crying can sometimes be a sign of discomfort due to teething. If your baby is around the age where teething begins (usually between 4 and 7 months) and is showing other signs of teething like drooling, gnawing on things, or swollen gums, this might be the cause of the sleep crying.

Q5: Is sleep crying a sign of sleep regression?

A: Sleep regression is a period when a baby or toddler who has been sleeping well suddenly starts waking up at night and having shorter naps, or skips naps altogether. If your 4-month-old baby has been sleeping well and suddenly starts waking up crying, it might be due to the 4-month sleep regression.

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