Understanding the 4-Month Sleep Regression

Four months is an exciting milestone when it comes to your baby's sleep. For the first few months of life, their sleep was all over the map. They didn’t know night from day, and they tended to sleep in random, disorganized chunks. At 4 months old, though, many parents start to breathe a sigh of relief as their baby’s sleep begins to consolidate into longer chunks, with more sleep finally happening at night.

“It is very common for a baby around the 4-month mark to have sleep regression, and it can be very frustrating for parents,” says Preeti Parikh, MD, pediatrician and executive medical director at GoodRx. “It is understandable since around 4 months of age, parents finally get some long stretches of sleep, and then the baby regresses.”

The 4-month sleep regression can definitely be a stressful and confusing experience, but with a little understanding of what’s going on, and some tips for coping, you can make it through to the other side.

What Is a Sleep Regression?

As much as we all wish and hope that our baby’s sleep will only keep getting better as they get older, baby sleep doesn’t always follow a completely linear pattern. There will be times that your baby sleeps fairly well, and other times that their sleep will seem to get worse, or regress backward.

“A sleep regression is a time period when your baby suddenly changes their usual sleep patterns, resulting in night wake-ups, missed or short naps, or early mornings,” says Nicole Carpenter, a pediatric sleep consultant certified by the Family Sleep Institute.

Carpenter says that sleep regressions are usually linked to developmental milestones. “You may notice your child developing new skills alongside a sleep regression,” she says.

Dr. Parikh agrees and adds that sleep regressions may also be caused by growth spurts or other external causes. “Sleep regressions will happen at different stages of the baby’s life when they go through big milestones and there can be other causes such as illness, separation and/or stranger anxiety, teething, travel, or external changes, too,” Dr. Parikh explains.

Importantly, understanding that dealing with sleep regressions is a normal part of raising a baby can help you manage your expectations when these regressions pop up, Dr. Parikh adds.

Signs of a 4-Month Sleep Regression

For most of us, the 4-month sleep regression is our baby’s first sleep regression, and that’s part of what makes it so challenging. After months of fragmented sleep, and a million nighttime wake-ups, many of our babies start sleeping a little better at 3 months, but then things go haywire sometime around the 4-month mark.

There are a few signs that may signal to you that your baby is starting to enter the 4-month sleep regression, says Carpenter. “Sleep may become more fragmented and your little one may begin waking many times throughout the night,” she describes.

Additionally, your baby may have a more difficult time falling asleep and staying asleep at night. Your baby’s naps may start to become difficult as well, Carpenter says. It may be hard to get your baby to nap, and their nap schedule may become less predictable.

All of this can lead to a very unhappy baby (and parent too!), says Carpenter. “They can become overtired which can lead to crankiness and difficulty falling asleep,” she explains.

Causes of a 4-Month Sleep Regression

In certain ways, your baby’s sleep is actually maturing at 4 months. “Prior to this milestone, your little one would sleep based on wake windows,” says Carpenter. Their sleeping did not follow a circadian rhythm, Carpenter explains, which is why their days and nights were mixed up.

At around 4 months, their circadian rhythms are becoming more adult-like, which means they will eventually be able to sleep deeper and longer stretches.

But what this also means is that they will have more periods of time where they need to switch between lighter and deeper sleep, which can be challenging. “Their circadian rhythm develops and they begin to have lighter phases of sleep and can wake up easier,” says Dr. Parikh.

It's not just how their circadian rhythms are changing at this age: Your baby is also going through several physical and developmental changes at 4 months that can affect sleep, Dr. Parikh notes.

“The common causes of sleep regression at 4 months is when they experience a big milestone development change such as rolling over and reaching for things,” Dr. Parikh says. Your baby may also start teething at this age, which can absolutely impact sleep, Dr. Parikh explains.

Your baby may go through a growth spurt at this age too, says Dr. Parikh, not to mention the possibility of illness or other life disruptions. In a nutshell, there is a lot going on with your little one at this age—all of which can wreak havoc on their sleep.

How to Manage a Sleep Regression

It can be super helpful and comforting to know that the 4-month sleep regression is normal and that it will pass. But that doesn’t mean that it isn’t difficult—and exhausting! Thankfully, there are things you can do to make this phase a little bit easier and to encourage healthy sleep habits for your little one.

Understand Your Baby’s Sleep Cues

During the first three months of life, most babies fall asleep at random times, and it may not be necessary to stick to a specific bedtime or naptime schedule. But around 4 months, as their circadian rhythms start to develop, you’ll want to put your baby down at around the same time each night.

You can figure out what time is the best bedtime for your baby by reading their sleep cues. It’s best to put your baby to sleep at the earliest sign of sleepiness—when your baby is rubbing their eyes, yawning, or starting to lightly fuss. If you wait until your baby is very cranky, they may be too wound up to fall asleep as easily.

Set the Stage At Bedtime

Creating a peaceful and sleep-inducing environment will help your baby fall asleep more easily, and stay asleep throughout the night. Whereas when your baby was younger, they may have fallen asleep anywhere, at any time, usually babies this age need a quieter environment to fall asleep in.

Consider keeping the lights dim for the hour or so leading up to your baby’s bedtime. You can start a bedtime routine that helps relax and soothe your baby. Many babies like a warm bath, and may even start enjoying being read to. Babies may find massage, rocking, and singing soothing as well. You can figure out what your baby likes best and establish a routine based on that.

Start Following a Nap Schedule

If your baby becomes overtired during the day, it will be more difficult for them to unwind at night for sleep. Starting at 4 months or so, most babies need regular naps, and establishing a nap routine will help them sleep better at night as well.

“To manage this sleep regression, I recommend beginning to try for a set schedule with naps and bedtime being based on biological sleep times,” says Carpenter. Four months is the age that most babies will take about three naps distributed throughout the day, she says. Usually, this will look like a morning nap at around 9, an afternoon nap around 1, and a third nap about two hours later.

Keep It in Perspective

Probably the most important thing you can do as a parent to get through the 4-month sleep regression is to have realistic expectations and keep things in perspective, says Dr. Parikh.

“To manage sleep regression, it is important to remind yourself that this will pass and to try not to blame yourself or get frustrated,” she explains. “Sleep regressions will happen throughout infancy and toddlerhood.”

As for when it will end? Most sleep regressions last a few weeks at a time. So your baby should be sleeping better before you know it.

When to Call a Healthcare Provider

It’s typical for your baby to have periods where they sleep poorly, and when they wake up multiple times a night, even after having stretches where they slept better. Most of the time, this is not due to a medical issue, but is just part of normal infant sleep.

“You should call your baby's pediatrician if they are not acting like themselves, showing signs of increased sleepiness or crankiness, hard to settle when they wake up, or not eating or drinking well and it’s going on for more than a few weeks,” Dr. Parikh advises.

Symptoms that may point to a sleep disorder in a baby may include colic, food intolerances, abnormalities in the airway, enlarged adenoids, or gastroesophageal reflux.

You should never hesitate to call your baby's healthcare provider if something feels “off” with your baby, says Dr. Parikh. “If you feel something is not right, it is always important to call your healthcare provider and err on the side of caution,” she says.

A Word From Verywell

Parents of infants are desperate for sleep as it is, so to see their sleep get worse instead of better can feel extremely demoralizing. Remember that the overall trajectory is for your baby to sleep better and better as the months go on. Your baby’s sleep actually is maturing, and your baby should be sleeping longer stretches at night before you know it.

That said, dealing with sleep deprivation can be really hard. Now is the time to adjust your expectations for what you can get done at home and in your personal life. It’s the time to accept whatever help is being offered to you. Remember to take care of yourself, too. And hang in there: In no time, your baby—and you—will be sleeping soundly.