4-month sleep regression: Causes, signs, and tips to help baby sleep


The first few months of being a parent are as exciting as they are tiring and exhausting. One challenge of caring for a newborn is getting them on a bedtime routine, and by the time your little one is around three months old, you’ll know the drill. Around this time, you’d have settled into a rhythm with your baby, finally settling into a more predictable sleep pattern,

But then, just as you start feeling that you’ve figured out your baby’s sleep schedule, suddenly, it feels like you’re back to square one. This is the reality of the infamous 4-month sleep regression—a curveball that catches many new parents off guard.

The 4-month sleep regression marks a significant shift in your baby’s sleep patterns, which will keep you and your baby up all night. As the first major sleep disruption since birth, no wonder parents have a lot of questions and concerns about this regression.

In this guide, we’ll delve into the intricacies of the 4-month sleep regression, understanding why it happens, how it affects your baby’s brain, and, most importantly, how to navigate this challenging phase with patience.

What’s the 4-month sleep regression?

The 4-month sleep regression refers to a sudden change in the baby’s sleep patterns around four months of age. It’s a developmental phase that many infants experience around the age of four months.

During the 4-month regression, your baby might struggle to fall asleep and stay asleep, often resulting in more frequent night waking and shorter naps. This regression can be challenging for both babies and parents, as it marks a departure from relatively stable sleep patterns.

Why does the 4-month sleep regression happen?

The 4-month sleep regression occurs due to significant developmental changes happening in your baby’s brain and body around this age.

According to Debbie Gerken, Certified Registered NICU Nurse, Certified Pediatric Gentle Sleep Coach, and founder of Sleep Like a Baby Consulting, “The 4-month period, between 3-4 months for some babies, marks a significant developmental milestone in sleep development because of a burst of brain development.

She states that for the first 3 months, a baby will sleep in two phases, 50% being active sleep. This active sleep can be seen as a baby grunts, groans, and wiggles about seeming as if they are awake, yet their eyes are closed.

“Newborns aren’t experiencing true deep sleep which is perfect for their immature nervous systems which may not be able to fully get them out of deep sleep,” says Gerken.

During the 4-month regression, or “progression” as I like to call it due to all the resulting development physically and mentally, babies begin to sleep in cycles more like an adult, transitioning from shorter cycles to longer ones in a more structured pattern.”

Gerken also suggests that for a baby whose brain is developing rapidly and causing them to be more curious and aware of the world around them, there may be more frequent awakenings as they get to the partial arousals and become more heightened to the world around them.

“In addition, whereas a newborn drifts easily in and out of sleep, a baby will now start off sleep from a much more awake state, making getting them drowsy difficult, let alone sleeping or going back to sleep,” she says.

What’s happening inside your baby’s brain during the fourth month?

During the fourth month of your baby’s life, remarkable neurological developments are occurring within their brain. These changes play a significant role in their sleep patterns and overall development.

  • Your baby’s sleep-wake cycle starts maturing. At around four months, your baby’s brain undergoes a significant transition, moving towards a more adult-like sleep pattern. This means that instead of experiencing short sleep cycles with frequent awakenings, they begin to consolidate their sleep into longer stretches.
  • Your baby’s awareness and cognitive development increase. Their sensory perceptions become more refined, and they become more attuned to their environment. This can make it easier for them to become stimulated and more challenging for them to settle into sleep.
  • Your baby starts showing signs of social and emotional development, such as smiling, babbling, and showing interest in interacting with others. This growing awareness of social cues and connections can influence their sleep patterns, as they may seek comfort and reassurance from you when they’re feeling distressed or uncomfortable.

Understanding these developments can help parents navigate the challenges of the 4-month sleep regression with patience and support.

Signs of the 4-month sleep regression

According to Gerken, “Some common signs of the 4-month sleep regression include frequent night wakings, increased fussiness, distractibility during feedings, changes in feeding patterns, increased clinginess, and difficulty settling and falling asleep.”

Here are some other signs that your baby may be going through the 4-month sleep regression include:

  1. Increased night waking: Your baby may start waking more frequently during the night, interrupting their previously longer stretches of sleep.
  2. Shortened naps: Their daytime naps may become shorter in duration, making it challenging for them to get enough daytime rest.
  3. Restlessness during sleep: Your little one may appear more restless or fussy while sleeping, tossing and turning more frequently.
  4. More frequent feeding: They may show an increased desire to nurse or feed during the night, possibly due to changes in their sleep patterns or growth spurts.
  5. Increased fussiness: They may seem more irritable or fussy during the day, possibly as a result of disrupted sleep at night.
  6. Changes in sleep schedule: Their sleep schedule may become more erratic, with unpredictable wake-up times and nap durations.

Causes behind your baby’s 4-month sleep regression

Developmental milestones

The 4-month sleep regression often coincides with significant developmental milestones in your baby’s life, including increased awareness of their surroundings, improved motor skills like learning to roll over, and enhanced cognitive abilities. As your baby’s brain matures and their awareness of the world grows, they may experience changes in their sleep patterns.content

Increased awareness and sensitivity

At around four months old, babies become more aware of their surroundings and may experience heightened sensitivity to stimuli such as light, noise, and temperature. This increased awareness can make it more challenging for your baby to settle down to sleep and stay asleep, as they may be easily disturbed by external factors. 

Changes in sleep cycles

Around the age of four months, your baby’s sleep cycles undergo significant changes as their brain transitions to a more adult-like pattern of sleep. Instead of cycling between active (REM) and quiet (non-REM) sleep every 50-60 minutes, they begin to experience longer periods of deep sleep followed by lighter stages of sleep. These changes can result in more frequent night awakenings and difficulty settling back to sleep.

When does the 4-month sleep regression start and end?

The 4-month sleep regression typically begins around four months of age.

However, the duration of the regression can vary from baby to baby. Some infants may experience the regression for a few weeks, while others may struggle with disrupted sleep for a bit longer.

How to help baby navigate the 4-month regression

“To proactively support the 4-month sleep regression, I recommend parents to establish a consistent routine starting at 3 month of age if not already in place,” says Gerken.

The consistency of a calming routine helps to signal to the baby that sleep is coming. With to routine of each step, the body is signaled to start winding down and getting ready for sleep. This allows the baby’s body to work with them in achieving sleep, which is supportive when a baby goes through the regression and going from very awake to drowsy becomes more challenging.”

Here are some tips by Gerken that might help your little one navigate their 4-month regression:

  • Creating a sleep-optimized environment of darkness
  • Comfortable temperature
  • White noise also supports sleep
  • Working on monitoring the baby’s wake windows, the time from being awake at one sleep opportunity to being asleep at the next, appropriate for their age
  • sleep durations can help prevent overtiredness for the baby and thereby making sleep easier for them.

How to handle baby’s 4-month sleep regression: Tips and tricks

Handling your baby’s 4-month sleep regression can be challenging, but there are several tips and tricks you can try to help both you and your little one get through this phase:

  1. Establish a consistent bedtime routine: Babies thrive on consistency. Sticking to the same activities and timing each night can help you create a sense of predictability and security for your baby.
  2. Create a conducive sleep environment: Keep the room dark, quiet, and comfortably cool. Use white/pink/brown noise to drown out any disruptive sounds.
  3. Implement a soothing bedtime routine: You could give them a warm bath or gentle massage before bed.
  4. Consider sleep associations: Babies often develop sleep associations and then struggle to fall asleep without them. This could be a need to be rocked or wanting to be nursed to sleep. Be mindful of any sleep associations and encourage independent sleep habits by gradually reducing reliance on these associations.
  5. Seek support: Don’t hesitate to reach out for support from family, friends, or healthcare professionals if you’re feeling overwhelmed or unsure how to help your baby through the sleep regression.

Are there any potential long-term effects of the 4-month sleep regression on a baby’s sleep habits?

“Typically, there are long-term effects of the 4-month sleep regression,” says Gerken, “Variables such as medical issues with a baby, simultaneous illness, and/or how parents navigate through the regression can cause some challenges after the regression is over.”

For example, if a baby is really struggling during the night and parents bring the baby into bed with them, it can be difficult to transition the baby back into their sleep space oncethe baby is doing better. In that example, I try to encourage parents to support and give their baby the extra comfort they want and need during this time, without changing their sleep environment.”

If a baby gets too overtired during a sleep regression and builds a significant sleep deficit, they can become more resistant to sleep and therefore, struggle more with getting to sleep or back to sleep. Consequently, a greater sleep deficit can build. To avoid this issue, Gerken advises parents to maintain consistency, prioritize day and night sleep schedules and monitor wake windows to optimize sleep during and after the regression.

How to prioritize self-care and manage sleep while supporting your baby

“Parents can prioritize self-care and manage their own sleep during this time, sharing in responsibilities, utilizing a support network, and practicing stress-relief techniques,” says Gerken.

Here are some tips by Gerken that might help you:

  • If possible, due to work commitments, parents can take turns or take shifts to help manage the night wakings. This allows each parent to get a chunk of restorative sleep.
  • Reaching out to family and friends for daytime support can allow time for parents to rest and reset.
  • Engaging in relaxation techniques such as deep breathing, meditation, yoga, short walks, etc. can support their own stress levels and promote sleep when it is possible.


Navigating the 4-month sleep regression can feel like a daunting challenge, but remember, you’re not

The disruptions that the 4-month sleep regression brings in your baby’s sleep are a natural part of their development and growth milestones.

By understanding the causes and signs of this regression and implementing the strategies that suit you and your baby the best, you can help your baby—and yourself—transition through this phase with greater ease.


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