Understanding the Four Month Sleep Regression

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The four-month mark feels like a huge milestone for parents when it comes to baby sleep. After living with a newborn who didn’t know night from day and tended to sleep in random, disorganized chunks, parents start to breathe deep sighs of relief when their baby’s sleep begins to get consolidated into longer chunks, with more sleep happening at night than during the day.

But sometimes babies have other plans. Enter the four-month sleep regression. Suddenly your peaceful dreamer seems to be waking up a whole lot more. They may be sleeping more fitfully or waking more frequently at night. Their naps may suddenly be shortened, and it may become more difficult to get them to fall asleep in the first place.

All of this leaves parents feeling confused, demoralized – and of course, utterly exhausted.

What Are Sleep Regressions?

As frustrating as it is for your baby’s sleep to suddenly go downhill, rest assured this sort of thing is normal. Blame it on the dreaded “sleep regression,” a period of poorer sleep for babies that is usually linked to developmental changes.

The first 12 months of your baby’s life involve many periods of rapid brain development, which can have an impact on their sleep. Sleep regressions also tend to coincide with growth spurts, which can happen at any time.

Perhaps the most difficult aspects of sleep regressions are that they seem to pop up out of the blue, just when you think that your baby’s sleep has improved. Don’t worry: you have not lost progress; once the sleep regression is over, your baby will continue to move toward more mature sleep patterns.

Sleep regressions are temporary and usually pass within a matter of weeks. Once they pass, both you and your baby will be catching those precious zzz’s again.

What Are Signs of the Four Month Sleep Regression?

The four-month sleep regression is perhaps the most challenging sleep regression because it’s your baby’s first one! So many parents get thrown for a loop because they expect their baby to start sleeping better at this point, not worse. But knowledge is power, and knowing how to recognize that you are in the midst of a sleep regression can be a sanity-saver.


The sleep regression starts around four-months-old but may happen a few days or weeks earlier, as it may coincide with an earlier growth spurt.


  • Your baby may wake more often at night or sleep more restlessly
  • Your baby may be extra hungry and fussy
  • Your baby may be more difficult to settle into sleep
  • Your baby may nap for shorter periods of time or resist naptime
  • Your baby may be generally more cranky and irritable

What Are the Causes?

Part of the frustration with the four-month sleep regression is that the causes aren’t obvious. Unlike when your baby is teething or sick, you can’t always tell from outside appearances what is happening with your child to make them so wakeful. Again, it all goes back to what is happening developmentally in their brains and bodies, and all the amazing ways they are growing, changing, and maturing.

During the four-month sleep regression or soon afterward, you may find that you have an entirely different baby than you did just a few weeks ago. That is because your four-month-old is becoming a much more social being, and is beginning to understand the world around them in new ways.

What’s Going on With Your Four-Month-Old

  • Your baby is much more social and may smile and coo at you
  • Your baby may become more upset when playtime ends
  • Your baby will start let you know when they are happy or sad, and their cries for each emotion will become more distinct
  • Your baby will study your face closely and follow objects as they move from side to side
  • Your baby is becoming stronger: they can hold their head up without support, start to roll from tummy to back, may push up to their elbows while lying on their belly, can hold a small toy in their hand, and may begin bringing their hands to their mouth

How to Cope

While it can be enormously helpful to know that the four-month sleep regression is normal, and represents some exciting developmental changes for your baby, that doesn’t mean it isn’t difficult (and did we mention exhausting?). Although there isn’t much you can do to eliminate the challenging turn your baby’s sleep has taken, there are things you can do to cope as a parent during this phase, and ways you can encourage healthy sleep habits for your baby.

Understand the Signs of Sleep Readiness

Sometimes parents miss the window of time when their baby is most likely to fall into sleep easily, and if that opportunity is missed, your baby will likely become wound up and less likely to fall asleep.

Try to put your baby to sleep as soon as you see signs that they are tired. Look for a baby who is rubbing their eyes, yawning, becoming less interested in the world around them, and starting to fuss.

Encourage Regular Naps

Parents sometimes believe that allowing their baby to nap during the day will equal less sleep at night, but nothing could be further from the truth. A baby who is well-rested during the day will be calmer and more likely to go down easily at night. At four months old, most babies are sleeping 14-15 hours total and taking between 3-4 naps per day.

Create a Sleep-Inducing Environment

When your baby was a newborn, they would pretty much fall asleep anywhere, even in a bright or noisy environment. Now that your baby is more aware of the world around them, they usually require a quieter, more peaceful sleep environment. At this age, you can establish bedtime routines that signal to your baby that it’s time to sleep. Here are some tips to consider.

  • A warm bath
  • Reading books
  • Rocking
  • Infant massage
  • Playing calming music
  • Dimming the light at least an hour before bed
  • Minimize engaging stimulation

Keep Realistic Expectations for Sleep at Four-Months

Although by four months your baby has started to regulate their sleep cycles much more than when they were newborns, most babies do not start sleeping through the night (defined as sleeping more than six to eight hours) until about six months old. Even then, only two-thirds of babies are doing so, according to Stanford Children’s Health. Knowing that most four-month-olds don’t sleep through the night — and that period of increased wakefulness caused by sleep regressions are common — can be assuring for parents who are concerned about sleep milestones.

When Will It End?

The question all exhausted parents have about the four-month sleep regression is: When it will finally be over? The good news is that although all babies are different, most sleep regressions only last a few weeks at a time. Before you know it, your baby will begin sleeping more soundly. You may find that they will sleep even better than they did previously because they have finished a period of developmental maturity, which often results in better sleep.

Is There a Medical Issue?

Many parents become concerned that a change in their baby’s sleep habits signals a larger problem that requires medical attention. It is always wise to trust your gut on these things, and if you believe there is something concerning happening to your baby, make an appointment with your doctor for an evaluation.

If your baby has been sleeping normally and suddenly begins waking more frequently or is having a harder time going to sleep, this is probably just your run-of-the-mill sleep regression. However, it is possible that your baby has a sleep disorder or medical condition that is interrupting their sleep.

According to Stonybrook University Hospital, the following conditions may be behind a sleep disorder affecting an infant: colic, food intolerances, airway abnormalities, gastroesophageal reflux, or enlarged adenoids.

When to Call a Doctor

There are some signs your baby may exhibit during sleep that warrant a call to your doctor, as described by the Cleveland Clinic.

  • Your baby is crying inconsolably and nothing will soothe them
  • Your baby is not breathing normally or gasping for air during sleep
  • Your baby is lethargic to the point where they become difficult to wake from sleep
  • Your baby does not want to engage in normal activities
  • Your baby is not interested in eating

Practice Safe Sleep Habits

Additionally, you want to make sure in all cases that you are practicing safe sleep habits with your baby. At four months, your baby should be:

  • Put to sleep on their back
  • Sleep on a firm surface (no couches or armchairs)
  • Be clear of any blankets, sheets, sleep positioners or toys that could cause suffocation, entanglement, or entrapment.
  • Swaddling and pacifier use is considered safe, and both can help encourage healthy sleep.

A Word From Verywell

Baby sleep is stressful and wearying enough as it is, so when you are faced with a sleep regression, it is natural to feel upset and even desperate. Remember that your baby has not lost progress in the sleep department. At four months old, they are progressing toward more mature sleep and will be sleeping in longer stretches before you know it. Soon they may even be sleeping through the night.

As you make your way through this sleep regression, remember to take care of yourself, too. Pare down outside activities, if possible, and nap or rest whenever the opportunity presents itself. It’s important to understand that, like all difficult baby phases, this too shall pass, and soon everyone — including you — will be sleeping soundly again.

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9 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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