Oh, the dreaded 4 month sleep regression! If baby just won't sleep anymore, see if you can keep your eyes open long enough to read this. We'll explain why baby isn't sleeping, how long you can expect the 4 month sleep regression to last, and what exhausted parents can do to help get baby back on track.

4 Month Sleep Regression: How to Stop the Madness!

You finally got baby to sleep for long stretches at night, then—BAM!—the 4 month sleep regression hits, and you’re right back at square one. Where, oh where, has my sleeper gone?!

If you can keep your eyes open long enough, this post will explain:

  • What is the 4 month sleep regression?
  • Why does the 4 month sleep regression happen?
  • How long does the 4 month sleep regression last?
  • And, most importantly, what’s the best way to survive the 4 month sleep regression? 😜

What Is the 4 Month Sleep Regression?

The 4 month sleep regression is when a baby’s brain makes a developmental leap and his/her sleep cycles change. Though referred to as the “4 month” sleep regression, it generally happens between 3 and 5 months of age.

When a baby is a newborn, their sleep is disorganized and is not governed by the circadian rhythm. They fall asleep easily, but never enter a true deep sleep, sleeping at odd intervals throughout the day and night.

Around 4 months, their sleep becomes more like an adult’s, with 45 minute sleep cycles governed by the circadian rhythm. Here’s what a typical sleep cycle looks like:

  • 0-10 minutes: Falling lightly asleep
  • 10-20 minutes: Settling into a deeper sleep
  • 20-30 minutes: Heavy sleeping
  • 30-40 minutes: Coming out of a heavy sleep
  • 40-45 minutes: Lightly sleeping and easily awoken

If an adult wakes during those lighter periods of sleep, they generally fall back asleep without even realizing it.

A baby, on the other hand, hasn’t yet learned to fall back asleep. They may wake fully and be fussy or even want to play.

What Causes the 4 Month Sleep Regression?

We’ve established that brain development is the main cause of the 4 month sleep regression, but there are other factors that can affect the severity of the 4 month sleep regression.

1. Other Milestones

“[The 4 month sleep regression] affects children differently depending on temperament and what other milestones it happens to coincide with. There is a lot going on at this time for your baby!” — Katelyn Thompson from Sweet Pea Sleep Solutions

It may be hardly noticeable for a baby with an easy-going temperament who hasn’t started rolling or teething yet. For others—perhaps a sensitive child who is learning to roll or popping a first tooth—it can be a seriously difficult time for all involved. 😬 Here are some baby milestones that occur around the same time and might interrupt sleep: 

2. Increased Appetite

If your baby is waking excessively through the night, he/she could be hungry. Breast milk digests in about 2 hours, and baby is having insane growth spurts that require extra energy.

And, interestingly, lactation follows the circadian rhythm. Prolactin production increases after the sun goes down, meaning you make more milk during the night. (Why oh why?!) Babies wake up to nurse because they know it’s there waiting for them, like ice cream in the freezer for a midnight snack (source). What’s even more fascinating is that nighttime breast milk is fattier, more filling, and contains extra melatonin—the hormone needed to fall asleep.

3. Need for Physical Affection

Then there’s their need for physical affection (which is a real, biological need!). At this age, baby still hasn’t been outside the womb longer than he or she was in the womb. Maybe baby is awake because she needs to reconnect with mama? If mom works away from home, baby will play catch-up breastfeeding during the nightly hours.

In fact, research shows that many babies nurse most frequently between 9 p.m. and 3 a.m. (especially in the early weeks and months)—they can take in as much as 20% of their total daily caloric needs at night. 

4. Unfavorable Sleep Environment

Sleeping areas that are too bright, too loud or quiet, or too warm or cold will prevent baby from getting comfortable. Think about your own sleep needs—you probably prefer a temperate, dark space. Then consider that baby is still adjusting to the bright, loud, cold world. It only makes sense that they’d be very sensitive to their environments. A 4-month-old may need exterior sleep aids like blackout curtains, white noise makers, and a sleep sack.

5. Lack of Daytime Stimulation

A 4-month-old’s brain is on overdrive, observing the world around them. Challenging that growing brain with reading, age-appropriate toys, sensory play, and other stimulating activities can help tire baby out. Just like if we stay indoors and sit on the couch all day, sleep may not be as appealing or deep if baby hasn’t had enough activity. (We discuss ideas for daytime stimulation below.)

How Long Does Sleep Regression Last For?

Not forever! 😜 Experts say the 4 month sleep regression phase generally disrupts naps and night sleeps for 2-6 weeks.

“Don’t think you’ve done anything wrong or that there is something wrong with your baby. This is a typical developmental milestone, and you often have little control over how much it will affect your little one. Know that ‘this too shall pass,’ but in the meantime, definitely work on good sleep habits and keeping your child from becoming too overtired during this phase.”  — Katelyn Thompson from Sweet Pea Sleep Solutions

What to Do When Your Baby Won’t Sleep

This 4 month sleep regression time is hard, especially since it often comes just as your baby was getting into a good sleeping groove! Some mamas also go back to work right around this time. Having that new schedule turned upside down in an instant is brutal!

It’s not a result of anything you’ve done and there’s nothing wrong with your baby—the 4 month sleep regression is totally normal. 

This too shall pass, and in the meantime, use these day and nighttime strategies to work on good sleep habits:

During the day…

  1. Catch some rays. Good sleep starts first thing in the morning. Exposure baby to natural daylight to help calibrate his day-night cycle. As the sunlight reaches the iris, it actually sets the circadian rhythm for the day and can support a good sleep at night.
  2. Get fresh air. The great outdoors is full of sounds, sights, smells and experiences that are rich food for baby’s brain. And if you need more convincing, one study suggests babies who spend more time outdoors in the afternoon sleep better. You can even experiment with an afternoon nap outdoors in stroller, a popular Scandinavian practice. Of course, be sure baby is properly dressed and kept warm.
  3. Stimulate their brains. These are the wonder weeks, so stimulate that growing little brain, which may wipe them out by bedtime. Try:
    • Talk to baby; imitate her; smile and look into her eyes. If you need to get chores done, babywear her. All of this connection stimulates baby’s brain.
    • Avoid screen time of any form for your small baby. It’s been associated with reduced sleep in babies, plus it’s not good for their developing brains!

In the evening…

  1. Introduce a bedtime routine.  At this age, baby is improving his or her memory and pattern recognition. Introducing a gentle routine and working on independent sleep associations is a good idea. An infant bedtime ritual might include:
    • Dimming lights (artificial light and blue light hinders melatonin)
    • Giving a warm bath (maybe with Epsom salts if doctor approves)
    • Massaging baby’s scalp, arms, legs and feet with coconut or olive oil
    • Speaking quietly to baby while changing their diaper and putting on cozy PJs
    • Playing soft music or singing a lullaby
    • Reading a story or saying a bedtime prayer
    • Giving kisses and snuggling
    • Final nursing session or bedtime bottle: “filling up the tank” or “topping off baby” right before bedtime is important for lengthening the time baby sleeps.
    • Finally, the proverbial, “Lay baby down drowsy, but not asleep.” This allows baby to self-settle enough that when he or she wakes again between cycles, they may be able to self-soothe as a matter of routine.
  2. Promote a peaceful sleeping environment. At 4 months, most babies can roll over, so swaddling is no longer appropriate. Instead, try:
    • blackout curtains
    • a white noise machine
    • an age-appropriate sleep sack
    • Safely diffusing 1-2 drops of lavender or chamomile essential oils. These oils have relaxation properties and help calm baby.
  3. Pause. When baby wakes in the night, give her a moment to self-settle before picking her up. She may surprise you by transitioning to the next sleep cycle on her own.
  4. Shhh! If you need to change a diaper or feed in the middle of the night (and you probably will), don’t play with baby or do a lot of talking. This stimulates the baby’s brain to an even more wakeful state. During the night, business is business and it’s good baby knows that.
  5. Dream feed. Before you go to bed, you could try gently “waking” baby to feed and putting baby right back down to sleep. In one small study, this did help baby sleep longer durations at night.
  6. Ride the wave. The relaxed approach is perfectly acceptable. If nursing-on-demand is how you do parenting, there is really no reason to change anything. If you’re a cosleeping parent, the sidelay breastfeeding position is a secret weapon to soothe baby back to sleep while safely getting a few Zzz’s yourself.

My Baby Still Won’t Sleep!

“For some babies, the [4 month sleep regression] coupled with very dependent sleep habits and an unpredictable schedule can cause an overtired cycle that can last far beyond the regression.”  — Katelyn Thompson

You may want to try a sleep consultation. Speaking to a pediatric sleep consultant that understands your style of parenting is invaluable. They can help you tweak your baby’s sleep association, offer product suggestions, and coach you through the tough times. Many offer Skype sessions. Find one here

If you’ve tried everything (including giving it some time), you should visit your pediatrician to rule out any underlying medical condition.

How About You?

Did you experience the 4 month sleep regression? What strategies did you use to combat the exhaustion? How did you manage to get baby on a schedule that works for your family?

  1. This was so helpful first just by finding out that sleep regression in 4 month olds in common.
    I am going to try the suggestions and will be glad to report the results. Thank you.

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About the Author

Genevieve Howland is a childbirth educator and breastfeeding advocate. She is the bestselling author of The Mama Natural Week-by-Week Guide to Pregnancy and Childbirth and creator of the Mama Natural Birth Course. A mother of three, graduate of the University of Colorado, and YouTuber with over 75,000,000 views, she helps mothers and moms-to-be lead healthier and more natural lives.

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