4-Month Sleep Regression: What’s Going On (and How to Cope)
Healthy’s Summary
If your baby suddenly goes from “sleeping like a baby” to waking up every couple hours, welcome to the 4-month sleep regression—a totally normal (and exhausting) phase of infant development. Around this age, your baby’s sleep cycles start maturing, becoming more like an adult’s. That means lighter, more frequent awakenings, even if they were sleeping long stretches before.
You might notice changes like frequent night wakings, shorter naps, fussiness during bedtime routines, or trouble falling back asleep without help
This regression usually lasts 2–6 weeks and signals big growth in your baby’s brain and body. So, while it’s tough, it’s actually a sign that your little one is developing just as they should.
Why is my 4-month-old suddenly not sleeping?
Let’s break it down. Around 4 months, your baby’s brain starts transitioning to a more adult-like sleep pattern. Instead of drifting into deep sleep and staying there for hours, they now cycle through lighter stages of sleep more frequently—about every 45 to 60 minutes.
And that means they’re waking up. A lot.
You might also notice that:
- They need help falling back asleep after each cycle.
- Naps get shorter or harder to come by.
- They’re more alert during the day—maybe even rolling over or babbling more.
In short: your baby’s sleep system is leveling up. But they haven’t yet learned how to self-soothe when they hit those light-sleep stages.
How long does the 4-month sleep regression last?
Most parents report this phase lasting 2 to 6 weeks, though every baby is different. Some bounce back to better sleep quickly, while others may need more support.
Consistency is key. If you stick with calming routines and avoid forming new sleep habits you don’t want to keep (like feeding to sleep every time), you’re more likely to get through it with fewer long-term disruptions.
What helps with 4-month sleep regression?
There’s no one-size-fits-all fix, but some small shifts can go a long way. Start with a consistent bedtime routine. Even something as simple as a warm bath, a short book, and a lullaby can give your baby cues that it’s time to wind down. Predictability really helps regulate their internal clock.
Next, look at the sleep environment. Try to keep the room dark, cool, and quiet—white noise can be surprisingly effective at masking sudden sounds that might wake them up. Think of it like recreating the calm, cozy vibe of the womb.
Another trick? Pause before swooping in when your baby stirs. Sometimes they’re just cycling through lighter sleep and might settle on their own if given a chance.
It’s also smart to focus on full feedings during the day. If they’re getting most of their calories when the sun’s up, they may not need as many overnight wake-ups.
And while every family’s different, some parents consider gentle sleep training methods around this stage—if their pediatrician agrees and baby seems ready. That could mean helping them learn how to fall asleep without always needing a feed or a rock.
Ask Healthy
Is the 4-month sleep regression real or just a growth spurt?
Great question—and yes, it’s very real.
While growth spurts can disrupt sleep (and often show up around the same time), the 4-month regression is more about brain development. This stage in a baby’s development is when infants begin to develop circadian rhythms and consolidate night sleep—both big deals in baby biology.
You’re not imagining things. If your baby suddenly seems like a different sleeper, it’s likely not a fluke. It’s a transition.
The Takeaway
The 4-month sleep regression is a rough patch, but it’s also a sign your baby is developing exactly as they should. Hang in there. You’re not “spoiling” them by offering comfort—and you’re not failing if they’re not sleeping through the night.
If it feels overwhelming, you’re not alone. Every parent hits a wall at some point. Support is out there—whether it’s a pediatrician, sleep coach, or a chat-based tool that tailors help to your baby’s stage.
Want to dig deeper?
Thriving as a New Mom
Caring for a newborn can be both exciting and overwhelming. “Thriving as a New Mom” is designed to support you through these early months with tailored guidance, practical tips, and a space to track your well-being. From managing sleep schedules to finding time for self-care, this program helps you balance the challenges and joys of motherhood, empowering you to care for your baby while also caring for yourself.
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