The four month sleep regression
You’ve finally settled into a rhythm with your baby’s sleep—longer stretches at night, consistent naps, maybe even a full night here and there. Then suddenly… it all falls apart.
Welcome to the 4-month sleep regression—a developmental milestone that can catch even the most well-prepared parent off guard. The good news? It’s normal, it’s temporary, and there are things you can do to support your baby (and yourself) through it.
What Is the 4-Month Sleep Regression?
The 4-month sleep regression is a permanent change in how your baby’s brain organizes sleep. Around this age, babies transition from newborn-style sleep (which is deep and disorganized) to more adult-like sleep cycles that include both light and deep stages.
This means:
Sleep cycles become shorter (about 40–50 minutes)
Baby stirs or wakes more often between cycles
Sleep becomes lighter and more easily disrupted
What feels like a regression is actually a sign that your baby’s brain is developing and maturing—which is a good thing!
Signs of the 4-Month Sleep Regression
Not all babies hit this regression right at 4 months, but most experience it sometime between 3.5 and 5 months. Common signs include:
Increased night waking (even if they were sleeping through before)
Shorter naps or nap refusals
Trouble falling asleep
Early morning wake-ups
Fussiness and overtiredness
Why This Regression Feels So Hard
Unlike other regressions, the 4-month regression marks a permanent change in how your baby sleeps. They’re no longer a sleepy newborn who can fall back to sleep easily after being rocked or fed. They’re now cycling through light and deep stages—and may need help adjusting.
How to Support Your Baby Through the 4-Month Regression
1. Protect Sleep Routines
Stick to consistent bedtime and naptime routines. Predictability helps your baby wind down and feel safe.
2. Watch Wake Windows
Avoiding overtiredness is key. At this age, wake windows are typically 90–120 minutes. Stretching them too far can lead to even more fragmented sleep.
3. Encourage Full Feedings
Make sure your baby is getting full feedings during the day, especially if they’re waking more at night. Growth spurts can drive increased hunger.
4. Use Soothing, But Start to Fade Sleep Props
It’s okay to rock or feed your baby to sleep if that’s what works—but consider gradually reducing how much you’re doing for them, and giving them space to try settling with you instead.
5. Practice Independent Sleep (If You're Ready)
This can be a good time to gently introduce sleep skills—like putting baby down drowsy but awake, or giving them a few minutes to see if they can resettle between cycles.
6. Prioritize Daytime Sleep
Short naps are common, but try to offer multiple nap opportunities to prevent overtiredness. Motion naps (in the stroller or carrier) are okay during this season.
7. Give It Time
This regression typically lasts 2–6 weeks. It's developmental—not something you're doing wrong. With consistency, most babies adjust to their new sleep rhythms.
What Not to Do
Don’t panic and overhaul everything. Sudden changes to routines can make sleep even more confusing.
Don’t assume your baby is “broken” or that you’ve lost all progress. Sleep setbacks are part of development.
Don’t be afraid to ask for help—from a sleep consultant, your partner, or your support system.
The 4-month sleep regression can feel overwhelming, but it’s also a sign that your baby is growing exactly as they should. With the right tools, patience, and support, you will come out the other side with more resilient sleep habits.
Your baby isn’t broken. You’re not doing it wrong. And you don’t have to go through it alone.
Need support navigating the 4-month regression or building a sleep routine that works? I offer personalized, responsive sleep support for families in the thick of transitions. Reach out today to get started. [Insert contact or booking link]