Baby sleep

How to survive your baby’s 4-month sleep regression

Just when it seems like babies are getting the hang of the whole sleep thing, they stop sleeping. Don’t worry, sleep regression is real—and it’s normal.

How to survive your baby’s 4-month sleep regression

Photo: iStock/LisaValder

Delphine Nicholls Golan knew some damage control was in order. So by the door of the apartment unit next to hers, she placed a bottle of wine, a box of earplugs and a note: “Dear Neighbours: Apologies in advance for any late-night screams. I’m learning to sleep through the night,” signed “Aleph, 4 months.” The Toronto mom of two was in the throes of the dreaded 4-month sleep regression—that phase when infants who have been sleeping longer stretches at night suddenly stop. “Aleph went from sleeping three and a half hour stretches to waking every 45 minutes,” she says. “You start to go crazy.”

What is a sleep regression?

A sleep regression is a period of time when a baby who has previously been sleeping well suddenly starts waking in the night, or has difficulty settling down to sleep.

All babies experience numerous sleep setbacks in their first two years, but the 4-month sleep regression feels especially cruel. You’re massively sleep-deprived from caring for your newborn around the clock, and just when you think you might be inching toward a full night of sleep, the regression hits.


Common 4-month sleep regression signs and symptoms

Here are the tell-tale signs your baby is going through the 4-month sleep regression:

  • Difficulty falling asleep at bedtime or nap time
  • Frequently waking up in the night
  • Crying or fussiness when waking
  • A new resistance to naps
  • Overall reduction in the amount of sleep your baby is getting

What causes the 4-month sleep regression?

While it’s easy to feel like you’re doing something wrong, what’s happening at this stage is actually very right. “Your baby’s brain is waking up,” says Pam Edwards, a certified paediatric sleep consultant based in Grand Prairie, Alta.

Changing sleep cycles

You might notice your baby now jolts awake to noises he used to sleep through—it’s now much, much harder to transfer him to a crib. “Infants are in quiet sleep most of the time with no distinct sleep cycles,” says Edwards. “But at the four-month mark, a baby’s brain begins cycling through light (REM) and deep (non-REM) sleep stages, like we do.” However, infant sleep cycles are much shorter than a child or adult’s (around 30 to 50 minutes, compared with 90), and babies spend approximately half of their sleep cycle in light sleep after they hit sleep regression, which is why they’re so easily awoken.

Developmental leaps

Developmentally, babies are starting to roll. They’re doing it in their sleep, and they can get stuck mid-way, which can wake them up. Previous abstract concepts, like distance, begin to make sense—which is why playing peek-a-boo is suddenly so cool, but also why separation anxiety sets in. They can grab a toy and put it in their mouths, thereby coordinating two actions. “This may not sound like a big deal, but [they] realizing they have a deliberate impact on the world,” says Isabela Granic, professor of developmental psychopathology at the Netherland’s Radboud University and co-author of Bedtiming: The Parent’s Guide to Getting Your Child to Sleep at Just the Right Age. And just as it takes you longer to settle into sleep after a stressful, action-packed day, you can be sure your baby’s busy brain is having trouble gearing down, too.

Physical changes


If those big cognitive leaps aren’t enough to contend with, your baby probably isn’t eating as much during the day because he’s so busy rolling, grabbing, possibly even sitting. Throw teething pain into the mix, and it’s no wonder you’re up all night. To overcome sleep regression, your baby needs to get used to these new developments; and since many are here to stay, the key to surviving this stage becomes less about fixing a problem and more about adapting (and helping your baby adapt) to these changes.

4-months sleep regression: Tips for survival

Evaluate your sleep routines

“Take a look at how you’re putting your baby to sleep,” says Edwards. “If it’s taking 50 minutes to rock him down when it used to take five, something needs to change.” Is your lifestyle conducive to good sleep? If your little guy isn’t sleeping as well in a stroller, for example, he may need a more consistent sleep location. Try introducing positive sleep associations, such as a lovey or a sound machine, and by winding him down with calming activities, like reading a book together.

Reinforce healthy sleep habits and routines

For Nicholls Golan, that meant implementing the same sleep strategies she uses for her two-year-old son, Laurier: a regular bath and book routine at night, providing enough naps during the day (since sleep begets sleep), and putting her son down while still awake to enable self-soothing—an invaluable skill when you’re dipping into your own sleep reserves. “He’s sleeping through the night,” she says. “It worked!”

Resist the urge to sleep train

Granic advises against doing cry-it-out sleep training during this sensitive period. “If you do it during these big developmental transition periods, you are more likely to fail,” she says. However, she does recommend introducing or reinforcing healthy habits and routines.

Follow your baby's cues

Instead of following a rigid sleep schedule, take note of your baby’s natural sleep cues—yawning, eye rubbing, fussing—and put him down before he gets overtired. As for feeding? Try to keep your baby focused on the breast or bottle during the day as much as possible to eliminate nighttime feedings. With that in mind, your baby is growing rapidly, so don’t deny him at night, either. Just keep engagement to a minimum, and hopefully he’ll fall right back asleep.

How long does sleep regression last?


Sleep regressions are perfectly natural—even predictable, and they don’t last forever, typically, two to six weeks. The quicker you can adjust to your baby's cues and institute healthy sleep habits, the quicker they'll get back on track. 

“I think calling this stage a regression comes less from [the] not sleeping and more from the parents hitting their wall,” says Granic. Once you establish that your child isn’t sick, you understand the science behind their wakefulness and you know there is an end in sight, you can respond in a way that works best for you. Eventually, every child sleeps, says Edwards. “It’s not a magic trick. It’s a biological need.”

Once your baby is able to roll both ways in his crib, he may begin to sleep much better, Edwards adds. If your little guy is waking because he’s rolling and getting stuck mid-way, you may want to ramp up the tummy time.

What about the idea that the 4-month sleep regression is a myth? 

While some experts disagree on whether or not all babies go through timed regressions in their sleep patterns, your baby's sleep cycles definitely change around this time. How much your baby's sleep will regress depends on many factors.

About our experts: Pam Edwards, a certified paediatric sleep consultant based in Grand Prairie, Alta.


Isabela Granic is a professor of developmental psychopathology at the Netherland’s Radboud University and co-author of Bedtiming: The Parent’s Guide to Getting Your Child to Sleep at Just the Right Age.

This article was originally published on Jun 28, 2019

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