What You Need to Know About the 4-Month "Sleep Regression"

Let’s Dive Into the 4-Month Sleep Regression: Understanding the Phenomenon

The "4-month sleep regression" is a term that’s often thrown around, and honestly, the internet and social media can make it sound way worse than it has to be. Parenthood bloggers are quick to share their caffeine-filled days, warning you about weeks of chaos ahead. But here’s the thing: it doesn’t have to be that bad—and it certainly won’t last forever.

Some babies sail right through this phase, so don’t stress about something that might not even happen to you. Worrying about the 4-month regression before it hits can rob you of the joy and energy you need to care for your little one. Instead of anticipating sleepless nights, take a deep breath and keep your eyes on the road ahead.

If you're a first-time parent and your baby is still a newborn, consider using my Newborn Sleep Course, which focuses on sleep "shaping" (not sleep training). For many families, using this guide can help prevent the 4-month sleep regression altogether, setting your baby up for great sleep right from the start.

What Is the 4-Month Sleep Regression?

The 4-month sleep regression happens when your baby starts waking up frequently at night or having shorter naps. It's common for babies to wake up every 1.5-2 hours during the night or even as frequently as every 20-45 minutes after naps.

This phase can be tough for parents who’ve been used to longer stretches of sleep. If your baby falls asleep with help—rocking, nursing, or bouncing—they might struggle to transition between sleep cycles on their own. It can feel like a sudden shock, but don’t worry; this phase is temporary.

What Actually Changes at 4 Months?

Around 3–4 months of age, your baby’s sleep architecture matures. Before this, newborns spend more time in deep, restorative sleep and transition less frequently between stages. But around this time, they begin to cycle through sleep more like adults—moving between light sleep, deep sleep, and REM (dreaming) sleep every 40–50 minutes during naps, and 90–120 minutes overnight.

This developmental shift is permanent. It’s not a phase that passes—it’s a biological change. And because babies at this age often haven’t yet learned to fall back asleep on their own, they start waking up more often between cycles. That’s what turns “the regression” into a tough few weeks (or more) for some families.

Does Every Baby Experience the 4-Month Regression?

Not every baby will go through this regression. Some babies sleep 12 hours straight from 3 months old—these little ones are what I like to call "unicorns." If your baby isn’t one of these, you're definitely not alone. I was there too. But it’s important to remember: this phase isn’t permanent, and better sleep is ahead.

How to Navigate the 4-Month Sleep Regression

If your baby is under 4 months, my Newborn Sleep Course can be a game-changer. This guide focuses on shaping your baby’s sleep habits naturally, so they’re less likely to experience the 4-month sleep regression at all. No sleep training required!

If your baby is already between 4-6 months and you're still dealing with the regression after 2-6 weeks, you have a few options:

1. Do Nothing: Sometimes, the regression will pass on its own, typically within 2-6 weeks. In the meantime, focus on sleep hygiene to help your baby establish better sleep habits.

2. Start Sleep Teaching: You can implement gradual, safe, and research-based sleep teaching methods. This doesn’t necessarily mean night weaning, and it’s not about letting your baby cry it out. You can teach your baby to fall asleep independently in their crib, which will help them transition through sleep cycles more easily.

Sleep Training vs. Sleep Teaching: What’s the Difference?

While "sleep training" is often a term used to describe teaching babies to sleep, it's important to understand that there are many methods out there. The goal is to help your baby fall asleep independently in their crib, so they can sleep longer stretches without needing assistance to fall back to sleep.

No, sleep teaching doesn’t have to mean "cry it out" (CIO). There are many other methods you can choose from, such as gradual fading or the check-and-comfort method. It’s about finding what works best for your family.

How I Can Help

I work with families who are struggling through night wakings—whether it’s every 2 hours, every 45 minutes, or even all night long. Whether you're breastfeeding, formula feeding, or using a pacifier, I can guide you through proven, loving, and research-backed methods to help your baby sleep longer stretches.

Ready to get started? I offer self-led guides and courses, along with personalized sleep plans, to help you teach your baby how to sleep independently.

Check out my Baby Sleep Course, which walks you through every step of the process, from establishing a solid sleep foundation to creating a bedtime routine that works for you. You’ll be on your way to better sleep for both you and your baby!

References + Additional Reading

Books

• Ferber, R. (1985). Solve Your Child's Sleep Problems. New York: Simon and Schuster.

• Hookway, L. (2018). Holistic Sleep Coaching: Gentle Alternatives to Sleep Training for Health & Childcare Professionals. Praeclarus Press.

• Weissbluth, M. (2021). Healthy Sleep Habits, Happy Child: A Step-by-Step Program for a Good Night's Sleep. Ballantine Group.

Scientific + Educational Resources

• Biological Time Structure and Sleep Regulation in Infants

• Normal Sleep Patterns Across Ages

• Stages of Sleep – Sleep Foundation

• Sleep Physiology and Cycles – StatPearls