Smiles. Giggles. Sweet coos. There is so much to love about life with your 4-month-old! There is, however, one notable exception…

4-Month-Old-Baby Sleep Regression

Between three and four months, babies’ sleep can be upended with a massive sleep regression. This harsh wake-up call happens when bambinos suddenly start popping awake every other hour...all night. No wonder, parents who are finally getting some sleep can feel a little sucker-punched.

It probably happens because 4-month-olds are becoming little social butterflies. All babies wake two to three times a night, but by 3 months they often just slide back into sleep, without a peep. However, at this age, once they pop awake, they’re eager for your company.  Let’s face it…who wants to sleep alone? Your baby loves watching you, chatting, smiling…you are their superstar.

For some babies, this devilish sleep regression can upset the sleep routine for many months! But thankfully, sleep can usually be put back on schedule with a bit of help.

What to do?

  • Keep your baby’s daytime rhythm in check with some sunny time, each day. 
  • Shorten daytime naps to no more than 1.5 to 2 hours (even less if your baby is looking tired: staring, glassy eyed, yawning).
  • Offer milk more often during the day….and consider doing a dream feed.
  • Use a good rumbly sound—about 65 to 70dB.
  • If you have a SNOO, try locking the bed on level 1 or 2—all night long—and feel free to contact our SNOO sleep experts. 

If all else fails, this is usually the earliest age that pediatricians recommend sleep training.

Your 4-Month-Old Baby’s Development 

What should a 4-month-old be doing?

Around 4 months, your baby has become a skilled investigator. In fact, your pint-sized scientist is paying attention to all the comings and goings of things around them. 

For example, cause and effect: If I do this, then that happens…a true revelation for any human! With cause and effect, babies learn a lot about how the world works. This happens when you play peek-a-boo. When you disappear, your baby is a bit confused, but when you reappear…everything is right in the world, again. What is amazing, is that when you do this over and over, your little bean figures out that you will return, and they get excited—smiling and cooing—anticipating your happy face! And shortly after that, they you may notice those little wheels spinning in your baby’s brain when they begin to coo and even chortle, not in anticipation…but to make you do it faster (“Hmmmm…I noticed that when I laugh Mommy reappears even faster!”) 

Cause and effect will soon turn into the less than delightful game of intentionally dropping things, first to see where they go—then to hear them drop—and finally to engage you in picking them up again…and again!

4 Month-Old-Baby Making Strange Noises

You may have noticed that your little one has added babbling to their repertoire. Between those new goo-goo, gah-gahs and, emerging giggles—plus your baby’s existing grunts, cries, and squeals—it’s quite the symphony! These little noises are how your lovebug is expressing themself right now. Many months from now, these baby sounds will start turning into real words!

Your 4-Month-Old Baby’s Health

Growing and Growing and Growing

Although it’s “only” been four months, you can probably scarcely believe your baby once fit into those teeny-tiny newborn onesies. All that milk fuels the unbelievably fast growth of your baby’s brain and body. Babies usually double their weight by 5 to 6 months and triple it by a year! Perhaps that’s no big surprise, considering that a 16-pound 4-month-old drinking 28 to 30 ounces of full-fat milk a day is the equivalent of a 128-pound adult chugging 1.8 gallons (240 ounces) of whole milk per day. (That’s 4,800 calories…the same as eating almost three quarts of ice cream every day!)

During your baby’s 4-month check-up, your pediatrician should explain where your little chunk is on the growth chart. Keep in mind that “averages” only represent the average— plenty of healthy kids are at 80% and plenty are at 20%. Of course, ask your doctor if the baby’s growth is normal. If your doctor isn’t concerned, you shouldn’t stress either. 

Note: It’s amazing to realize that by 3 years your baby’s weight will be one-sixth of an adult’s, their height will be half of an adult’s…and their brain will be 80% the size of an adult head! (That’s why it gets so hard fitting shirts over those big noggins!) 

4-Month Checkup

The 4-month check-up there’ll be another round of vaccines. And, it’s your opportunity to ask about your babe’s development and what’s coming up over the next two months. 

For example, what’s on the feeding horizon?  There is no rush to start solid food. (It does make a breast-fed baby’s poop smell really yucky!) When you do start food—usually by 6 months—the food is really just for fun…and to get some valuable extra iron.

Note: It’s an old wife’s tale that solids help babies sleep better. After all, why would one or two spoons of rice cereal (which is pure-starch) be more filling than 6 ounces of milk (filled with fat, protein and carbohydrates)? 

 < Your 12-Week-Old Baby | Your 5-Month-Old Baby > 

About Dr. Harvey Karp

Dr. Harvey Karp, one of America’s most trusted pediatricians, is the founder of Happiest Baby and the inventor of the groundbreaking SNOO Smart Sleeper. After years of treating patients in Los Angeles, Dr. Karp vaulted to global prominence with the release of the bestselling Happiest Baby on the Block and Happiest Toddler on the Block. His celebrated books and videos have since become standard pediatric practice, translated into more than 20 languages and have helped millions of parents. Dr. Karp’s landmark methods, including the 5 S’s for soothing babies, guide parents to understand and nurture their children and relieve stressful issues, like new-parent exhaustion, infant crying, and toddler tantrums.

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.