4 Month Sleep Regression: A Complete Parent’s Guide to Surviving & Thriving in 2025

Did you know that 40% of parents report significant sleep disruptions during their baby’s 4 month sleep regression? Just when you thought you had your little one’s sleep schedule figured out, everything changes!

As a nurse practitioner who’s helped hundreds of families through this challenging phase, I can tell you that the 4 month sleep regression isn’t just normal – it’s actually a sign of your baby’s incredible brain development. Let’s dive into everything you need to know about this major sleep milestone and how to navigate it with confidence.

If your baby has been happily sleeping in their SNOO, now is the time to wean from that sleep aid and transition to the crib. See this post for help and tips to make the transition easier. https://justaskjennp.com/wean-baby-from-the-snoo/

What Is the 4 Month Sleep Regression?

• Definition and explanation of this developmental phase
  • Your baby’s sleep development is moving from the newborn sleep stage to the adult patterns of sleep cycles. This means that your baby will cycle through deep sleep and light sleep throughout the night. When the lighter sleep cycles occur, your little one can wake up and assess their surroundings. If those surroundings changed from the time they went to sleep (fell asleep in arms, and moved to a crib while sleeping), they may be scared and wonder where you are. 
• Why it’s different from other sleep regressions
  • This time it is an actual sleep development milestone, not behavioral shift
• Typical duration and timing (when it starts/ends)
  • Starting between 3-5 months of age
  • Ending around 6 months
• Science behind sleep cycles and brain development
  • As a biological change occurs in the baby’s brain to shift toward a mature sleep cycle, the periods of lighter sleep can cause night time waking if your baby is not accustomed to falling asleep on their own. 
  • Distractions and more awareness of their surroundings is also going on developmentally at this time.
    • Feedings are more of a challenge as they get too distracted to take a full feeding whether from the breast or the bottle. 
  • Rolling is also playing a factor. If they have just discovered their skill for rolling over, they might accidentally roll to their tummy when trying to sleep and get mad about that position. (Now is the time to remove the swaddle if you haven’t already.)

Common Symptoms of the 4 Month Sleep Regression

• Increased night wakings
• Shorter naps and nap resistance
• Fighting bedtime
• Changes in feeding patterns
• Increased fussiness and over-tiredness

10 Proven Strategies to Survive the 4 Month Sleep Regression

• Establishing consistent bedtime routines
  • Feeding, pajamas, brush teeth/gums, read a book, sleep sack, crib
• Creating an optimal sleep environment
  • Dark, quiet and cool room
  • Consider moving your baby to their own room if they wake due to hearing you or your partner at night
• Adjusting wake windows and nap schedules
  • Drop to 3 longer naps from 4
  • Wake windows expand to 90-120 minutes between naps and bedtime
• Using white noise and blackout curtains
• Managing feeding schedules
  • Try not to feed you baby at night- reverse cycling can occur when they are distracted with feedings in the daytime, then wake to feed at night
  • Encourage full feedings in the daytime
• Dealing with overtiredness
  • Try to catch your baby’s signs before the crying stage- lifting hands to eyes, rubbing eyes, yawning, looking away from you
• Supporting self-soothing skills
• When and how to start gentle sleep training
  • 4 months is the best time to introduce sleep training
    • When to consider sleep training
  • Babies are going through a developmental shift already, it’s a good time to help them achieve good sleep skills to help them as they grow
  • Be consistent- sleep training can happen quickly if you don’t change the rule every night
  • Place you baby in their crib while drowsy, but awake
  • Once your little one is in the crib, try not to pick him/her up again, you can pat and “shush” and rub and sing quietly, but try to resist rocking and holding
  • Leave the room once your baby is quieting again and only go in after a few minutes if they fuss again. Give them time to settle independently before you interrupt. 

How to Maintain Your Sanity During Sleep Regression

• Self-care strategies for parents
  • Prioritize your needs
  • Know that this is a normal developmental change, and you will get through it!
  • Be patient and roll with it
• Partner support and taking shifts
  • Take turns taking a walk when needed
  • Take shifts during the night 
• When to ask for help- whenever you need it!
  • Sleep consultants 
  • Family members
  • Friends with older babies/children
  • Primary Care Provider

What Not To Do

• Creating new sleep crutches
• Rushing to change sleep space
• Skipping naps to tire baby out
• Assuming it’s just a phase that requires no action

Remember, the 4 month sleep regression is temporary, but it leads to permanent changes in how your baby sleeps. While these few weeks might feel overwhelming, you now have the tools and understanding to help your little one transition through this important developmental phase. Don’t hesitate to reach out for professional support if needed – sometimes a little expert guidance is all you need to get back on track to restful nights. Your baby’s sleep journey is unique, and you’re doing an amazing job supporting their development!

For more details and helpful information, see this link https://www.sleepfoundation.org/baby-sleep/4-month-sleep-regression