4-Month Sleep Regression: Expert Tips to Survive & Thrive

What Is the Four Month Sleep Regression?

Nope, it’s not a bad dream; your 3-4 month old baby, who’s always been a great sleeper, is suddenly waking more overnight, is refusing naps, and is next-level fussy. What gives? Your baby could be experiencing the four month sleep regression. Sleep regressions are exhausting, but don’t stress! We’ve put together our best parent-sourced tips and tricks for helping your baby get through this developmental transition.

What Is Sleep Regression?

Sleep regression is a phase that occurs when your baby, who was previously a good sleeper, suddenly deviates from their predictable sleep habits. Your baby may begin waking up throughout the night, or refusing naps during the daytime (and they’ll definitely appear fussier). While not all babies experience sleep regressions in a distinctly noticeable way, they are developmentally typical and generally aren’t a cause for concern.

Though living through sleep regression is challenging for the whole family, it often signifies positive developmental growth and mastery of new skills for your baby. Think of it as your baby's brain upgrading its operating system, and sleep patterns are temporarily affected during this important installation process.

What Causes the Four Month Sleep Regression?

Newborn babies generally sleep most of the day and night, and wake primarily to feed. Their bodies do not recognize the difference between day and night, and they haven’t yet established circadian rhythms that define more adult sleep-wake cycles. Newborns primarily cycle between two sleep stages: active sleep (REM) and quiet sleep (non-REM).

Once your baby is around four months old, their body will begin producing its own melatonin, and start transitioning from newborn sleep to adult sleep. This is the core of the 4-month sleep "progression." Adult sleep is characterized by regular sleep-wake cycles, lasting from one to two hours (though a baby's sleep cycle is shorter, around 45-60 minutes at this age). The start of the cycle is when we experience our deepest sleep, and gradually, our sleep becomes lighter and we may experience a brief period of wakefulness before falling back into deep sleep. Babies now cycle through four stages of sleep, similar to adults, spending more time in lighter stages of sleep.

Some babies have a difficult time adjusting to this quick moment of awakening between sleep cycles, hence the four month sleep regression. For whatever reason—it may be that they’re beginning to roll over or that they wake up and realize they’re in a crib and not with Mom—they struggle to fall back to sleep on their own. Previously, they might have drifted seamlessly between their simpler sleep stages, but now, these brief awakenings are more pronounced. If they haven't yet learned to fall asleep independently, they will cry out for the same conditions or associations (like rocking, feeding, or being held) that helped them fall asleep initially. 

Other Contributing Factors to the 4-Month Sleep Regression:

• Developmental Milestones: Around this age, babies are often mastering new skills like rolling over, reaching, and becoming more aware of their surroundings.  This increased cognitive and physical development can make it harder for them to settle down and can lead to them "practicing" these new skills in the crib.   
• Increased Awareness: Your baby is becoming more engaged with the world. This heightened awareness can sometimes lead to overstimulation, making it more challenging to wind down for sleep.    
• Growth Spurts: While distinct from sleep regression, growth spurts can cause increased hunger and fussiness, potentially overlapping with and exacerbating sleep disruptions.    
• Changes in Sleep Needs: As babies grow, their total sleep needs decrease slightly, and the distribution of sleep between nighttime and naps shifts. This adjustment period can contribute to unsettled sleep.

How Long Will the Four Month Sleep Regression Last?

Now, some good news: sleep regressions are temporary. While there’s no precise timeline (because every baby is different), the four month sleep regression typically lasts 2-6 weeks (but you’ll feel every minute of it). The "regression" part – the frequent wakings and difficulty settling – is temporary. However, the change in their sleep architecture (cycling through more adult-like sleep stages) is permanent.  The goal is to help your baby learn to navigate these new sleep cycles.

Signs of Sleep Regression

By 3-4 months, your baby may be sleeping for regular 4-5 hour stretches at a time (stressing the word “may”). If your baby hasn’t reached this milestone, it’s still likely that they’ve developed a recognizable pattern of overnight sleep. If your baby suddenly deviates from their regular sleep, you may be experiencing the four month sleep regression. Signs of sleep regression usually include:

• Increased difficulty falling asleep (for naps and bedtime).
• Waking more frequently overnight.
• Increased fussiness, especially while waking or around bedtime.
• Nap refusal or suddenly taking much shorter naps (e.g., "catnaps" of 30-45 minutes).
• Shorter intervals of sleep.
• Increased crying when waking up.
• Wanting to be held for sleep more often.
• Changes in appetite (sometimes increased due to more wakefulness or an overlapping growth spurt).

Is It the 4-Month Sleep Regression, Teething, or Something Else?

It can be tricky to pinpoint the exact cause of sleep disruptions. Here’s a quick comparison:   

• 4-Month Sleep Regression: Characterized by a sudden shift from previously good sleep, frequent night wakings (often at the end of sleep cycles, every 1-2 hours), difficulty settling, and shorter naps. Usually coincides with the 3-5 month age range due to permanent changes in sleep cycles.
• Teething: May cause fussiness, drooling, swollen gums, a desire to chew on things, and sometimes a slight temperature (under 100.4°F/38°C). Teething pain can cause waking at any point in a sleep cycle, not just between cycles. Symptoms are often more pronounced a few days before and after a tooth erupts.    
• Growth Spurt: Often marked by a noticeable increase in appetite (baby seems constantly hungry) and may lead to more frequent waking to feed. Fussiness and clinginess are also common. Sleep may be disrupted due to hunger.    
• Illness: Look for other signs like fever (100.4°F/38°C or higher), cough, runny nose, vomiting, diarrhea, or a general appearance of being unwell. If you suspect illness, always consult your pediatrician.    

Often, these can overlap, making it even more challenging for parents! If your baby is generally healthy but sleep has suddenly deteriorated around the 4-month mark, the sleep cycle maturation is a very likely primary cause.

How Can You Help Your Baby Through the Four Month Sleep Regression?

Research demonstrates how important sleep is to infant development and to maternal wellbeing, so helping your baby with this transition benefits everyone in the household. And it’s an ideal phase to start introducing behaviors that reinforce “self-soothing” into your routine. Remember, the goal isn't to "fix" the regression, but to support your baby as they adapt to their new way of sleeping.

Optimize the Sleep Environment

• Create and maintain a consistent bedtime routine. A predictable bedtime routine helps your baby relax and understand what to expect when it’s time to snooze. This routine should be calming and consistent, lasting about 20-30 minutes. Examples include a warm bath, massage, putting on pajamas and a sleep sack, reading a story, and a quiet song.    
• Make sure your baby is sleeping in a dark environment, so they begin differentiating between daytime and nighttime. Use blackout curtains to make the room as dark as possible for all sleep (naps and night).  This helps with melatonin production. Consider a white noise machine to block out household sounds.  Ensure the room is at a comfortable temperature – not too hot, not too cold.  

Foster Independent Sleep Skills

• Begin putting your baby to sleep in their own sleep environment, whether that’s a bassinet or crib. When your baby wakes up in the middle of the night, their sleep environment will be familiar and won’t trigger panic. This consistency helps them associate their crib with sleep.
• Work towards putting your baby to sleep while they’re drowsy, but still awake. It helps your baby learn how to self-soothe and go back to sleep independently.  This is a crucial skill. If they fall asleep in your arms and then wake up alone in the crib, it can be jarring. Learning to fall asleep in their crib means they are more likely to resettle themselves when they naturally wake between sleep cycles.
• If your baby fusses when put down or wakes in the night, wait a few minutes before rushing in (unless you suspect they are unsafe or truly distressed). Sometimes they will resettle on their own. This gives them a chance to practice self-soothing.

Manage Daytime Sleep and Wake Windows

• Evaluate your baby’s wake windows. Your baby needs adequate time awake during the day to nap and sleep successfully. Ideally, your four month old should be awake 90-120 minutes between daytime naps.  Paying attention to age-appropriate wake windows can prevent overtiredness, which makes it harder for babies to fall asleep and stay asleep. An overtired baby often has more night wakings.
• Ensure Adequate Daytime Play and Natural Light: Active playtime during wake windows and exposure to natural daylight (especially in the morning) helps regulate their internal clock (circadian rhythm).
• If your baby is working on rolling or other motor skills, give them plenty of floor time during the day to practice. This can reduce their urge to practice in the crib at night. 

Feeding Strategies

• Try not to rely on overnight feedings to get your baby back to sleep if they are not genuinely hungry. Feeding can become a sleep association, and worsen (and lengthen the duration of) a sleep regression. Adding more breastmilk or formula to daytime feedings—either by increasing the frequency or duration—or cluster feeding right before bedtime will help curb hunger overnight. Ensure your baby is getting full feeds during the day. If you're unsure if your baby still needs night feeds for nutrition, consult your pediatrician. Many formula-fed babies can sleep 7 hours by 4 months, and breastfed babies by 6 months, without needing a night feed for calories.    
• Separate Feeding from Sleep: If possible, make feeding the first step of the bedtime routine, rather than the last. This helps break the association between eating and falling asleep. 

Address Swaddling

• If you’re still swaddling your baby, and they are showing signs of rolling over (or are close to it), it's crucial to transition out of the swaddle for safety reasons.    
• Replace your traditional swaddle blanket or sack with a transitional swaddle suit that allows for more freedom of movement like Love to Dream’s Swaddle UP Transition Suit, or a wearable blanket/sleep sack. This allows their arms to be free, which is necessary if they roll onto their tummy.

Coping Strategies for Exhausted Parents

Navigating the 4-month sleep regression can be incredibly taxing on parents. Remember to prioritize your own well-being too:    

• Take Shifts: If you have a partner, take turns handling night wakings so each of you can get a consolidated block of sleep.
• Ask for Help: Don't hesitate to ask for support from family or friends. Even an hour or two of help during the day can allow you to nap or rest.
• Practice Self-Care: As much as possible, try to incorporate small moments of self-care into your day, whether it's a short walk, a cup of tea, or a few minutes of quiet time.    
• Nap When Baby Naps (If Possible): This age-old advice can be a lifesaver during sleep regressions.
• Stay Patient and Flexible: Remember this phase is temporary. Try to remain patient with your baby and yourself. It's okay if things don't go perfectly.    

When to Consult Your Pediatrician

While sleep regressions are normal, contact your pediatrician if:    

• You suspect your baby is sick (e.g., has a fever, is unusually lethargic, or has other signs of illness).
• Your baby isn't gaining weight appropriately or has a significant decrease in appetite or wet diapers.
• The sleep disruptions are severe and you're concerned about your baby's overall well-being or your own ability to cope.
• Your baby seems to be in pain.
• Your baby is losing previously achieved developmental milestones.
• You have any concerns about your baby's breathing during sleep (e.g., snoring, mouth breathing).

Finding What’s Right for You

Albee Baby is the oldest family-owned specialty baby shop in the US, and we pride ourselves on providing our customers with the best assortment of baby products anywhere, at fair prices, always. We’re committed to being an inclusive resource for parents, and hope you’re feeling empowered to find the right baby gear for your family. Still have questions? Feel free to contact our baby gear experts at 877.692.5233 or by email at [email protected].