Understanding the 4-Month Sleep Regression
The 4-month sleep regression is one of the most talked-about stages in a baby’s sleep journey—and for good reason! It can feel like things were going smoothly, and then suddenly your little one’s sleep changes overnight.
When Does the 4-Month Regression Start?
Despite its name, the “4-month regression” doesn’t always begin exactly at 4 months. For many babies, it can start anywhere between 10 weeks and 16 weeks. Every baby develops differently, so the timing and impact will vary.
What Does It Look Like?
For some babies, the 4-month regression is a big challenge, while for others, it’s just a little bump in the road. Signs your baby may be going through it include:
Daytime naps: Your baby may start waking after around 40 minutes (the length of one sleep cycle).
Nighttime sleep: They may wake every 2 hours or so after their first longer stretch of sleep, which often ends around 10:30 pm.
Why Does This Happen?
At this stage, your baby’s sleep is maturing. Instead of drifting between newborn sleep stages, they’re beginning to cycle through light and deep sleep more like an adult does. This change is permanent—your baby won’t “go back” to newborn-style sleep—but that’s actually a good thing! It’s a sign of healthy brain development.
How Long Does It Last?
The regression itself usually lasts anywhere from 2 to 6 weeks, though it depends on your baby and how you respond. The key thing to remember is that it does pass, and there are gentle ways to help your baby (and you!) adjust.
What Can You Do?
Offer consistent routines: A predictable nap and bedtime routine helps your baby know what to expect.
Support self-settling skills: Giving your baby the chance to fall asleep on their own (even for one nap a day) can help them learn to connect sleep cycles.
Keep nighttime calm: Try to keep lights low and stimulation minimal during overnight wake-ups.
Be patient: This stage is tough, but temporary. Your baby isn’t “broken”—their sleep is developing.
The 4-month regression can feel exhausting, but it’s also a sign that your baby is growing and developing just as they should. With time, consistency, and support, your little one’s sleep will settle again.