May 10, 2020 13 min read

7 Surprising Things That Can Ruin Your Baby's Sleep - Why Your Baby Won't Sleep

I’m not going to lie…my baby’s imperfect sleep habits have made me feel like an utter failure.

I’m a part of a Facebook community of women that rock infant sleep. The bar is set so high. While most of the women posted about getting their baby to sleep for 12 hours, I was stuck firmly at 5-6.

For some women, 5-6 hours is the definition of sleeping through the night. For me, it was a slap in the face. Even after all of my preparation, the books I’ve read, and the sleep training I’ve tried, I could never get my baby to fully sleep through the night.

Now my daughter sleeps 11 continuous hours a night. What changed? I discovered that while I was working hard to train my daughter to sleep, I was also actively ruining her sleep by ignoring these hidden hindrances.

If your baby won’t sleep through the night, you’re not alone. So many families struggle with their baby’s wonky sleep habits. This post discusses the factors that might be preventing your baby from sleeping through the night. A great sleep environment is the foundation for amazing sleep. So, let’s dig in and figure out what’s keeping your baby up at night!

From Sleepless to Slumber Baby Sleep Series

If you’re just tuning in, this is the third post in my new baby sleep series, From Sleepless to Slumber. Baby sleep is one of the most important (and scary) aspects of motherhood. If you’re preparing for your baby or in the mix of exhausted, sleepless nights, then this is for you!

Why Your Baby Won’t Sleep: 7 Surprising Things that Kill a Baby’s SleepThe Real Reason Your Baby Won’t Sleep

In my opinion, this post is probably the most important of the Sleepless to Slumber series. Here we dive into what is actively ruining your baby’s sleep.

If you are dumbfounded by why your baby won’t sleep, you’re not alone. Baby sleep problems are extremely prevalent in the U.S. Not surprisingly, these baby sleep problems, turn into child sleep problems. In fact, 25-30% children and adolescents suffer from sleep disorders (You don’t want to know how many adults have sleep disorders…)

As my story hopefully shows, no amount of sleep training and schedules will be successful if you don’t take care of the elements that are actively ruining your baby’s sleep. 

Are you ready to figure out why your baby won’t sleep, Mama? Let’s get started!

7 Surprising Reasons Why Your Baby Won’t Sleep


1. Genetics

Are you a light or heavy sleeper? My husband could snore snooze through a nuclear holocaust. I’m not that person. You breathe wrong and I’ll wake up.

Like adults, babies have a predisposition for sleep.

A 2011 study by the Pediatric Journal found that while environmental causes and parental guidance mostly contributed to poor sleep habits, there is a genetic component that shouldn’t be ignored.

What to take from that?

Some babies are predisposed to sleep issues. This absolutely does not mean that your baby is doomed, but it does mean that you shouldn’t beat yourself up because your baby won’t sleep!

2. Your Baby’s Body

 (If you have an older baby, just skip this).

In the first few months, your baby will develop her motor skills from the top down. At first, her arms are these freaky flailing things that she randomly sees in the corner of her eyes. She has no idea that these things are hers, and they can be extremely distracting. 

This could definitely be the real reason why your baby won’t sleep. My best advice is to swaddle her up and see what happens. 

I know what you’re thinking: “But my baby doesn’t like to be swaddled!”

I get it, but if you have a wild, crazy baby, there’s a huge chance that your baby needs to be swaddled– even if she hates it at first! My daughter was like that. She screamed, flailed, and destroyed every carefully swaddled blanket I wrapped around her. Total Houdini baby.

So, I had to find a swaddle that could handle her. Once I did, it was heaven (My personal favorite is the Woombie swaddle and the Miracle Blanket).

Still not convinced? That’s okay. I wrote the next post for you! How to Swaddle a Baby (That Absolutely Hates Being Swaddled!)

If you’ve read my article on sleep training, then you know how I believe that an excellent bedtime routine is foundational to everything. If your baby doesn’t have an adequate bedtime/naptime routine, there’s a good chance that his naps are going to be short and unsatisfactory.

This is how I think of a bedtime routine…

College-me is on an outing with a guy-friend. We go see a horror movie, go go-kart racing, and eat the sloppiest BBQ you could ever imagine (paying dutch). At the end of the night, I go to high-five him and he tries to kiss me.

Wait, what?!

Totally out of the leftfield move! It was a total friend-date with no indication of romance. Suddenly he’s feeling romantic? You need a chick flick, flowers, flirting, a romantic dinner, you know?

Are you catching my drift?

When you’re trying to put your baby to sleep, you just can’t expect him to fall asleep on a dime. Melatonin comes into play here. Dim the lights, sing a soothing song, do some rocking (which is not a sleep prop in this instance). This winds down your baby’s brain, reduces cortisol, and lets the melatonin get to work.

How you create a bedtime routine is up to you, but whatever you do, keep it consistent.

I keep it simple. 10 minutes before she usually starts yawning, I wind things down and hold her. After the first yawn, I take her to her room, close the blinds, dim the lights, put on her sleep sack, and sit with her in my lap. We then cuddle for a while (about 2-7 minutes), sing our song, and I put her in her crib. Viola! Baby falls asleep on her own.

Does this seem like a foreign language to you? Eh, I hear you. It was for me too. The Secrets of the Baby Whisperer taught me everything I know about wind-down routines.  Her 4 S’s (Set the Scene, Swaddle, Sit, Shush-Pat) routine really was a game-changer.

HOLY GUACAMOLE, THIS IS A LONG POST! Please feel free to pin and come back later.

The Real Reason Why Your Baby Won't Sleep

4. Not Enough Sleep or…Too Much Sleep!

Baby sleep problems can be so confusing. Too much sleep, and you have baby bouncing off the walls at night. Not enough sleep and you still have a cranky little night owl.

There’s a fine line between too much sleep and not enough sleep during the day. When my daughter was younger, everyone commented on how she napped so much during the day (2 hours, 4x a day). For whatever reason, people believe that the less sleep babies have during the day, the more sleep they will have at night.

If there is one thing you take from this section: sleep begets sleep.

Our bodies produce a delicate balance of cortisol and melatonin. These two hormones are like yin and yang; cortisol stimulates us, keeps us awake and alert, while melatonin helps us wind down and go to sleep. 

Let me put this in terms of coffee since that’s my native dialect.

When you wake up, you take a shot of espresso. That makes you alert and helps you get what you need to get done. Over time, the effects of the espresso diminish, and you begin to crash. You have two options: either get a refill or take a nap. But, let’s say you take another shot and you remember that you’re supposed to go to bed early that night. Now you’re all amped up and sleepless!

Likewise, at the end of your baby’s wake cycle, her cortisol diminishes. She needs a nap to recharge. If she doesn’t, her body gives her another shot of cortisol which prevents her from settling in. When you try to put your baby down for a nap when she’s overtired, it’s literally like trying to fall asleep after you’ve had another shot of espresso.

This affects nighttime sleep as well. When she’s exhausted and strung out from all that cortisol, it’s just about impossible to wind down. (This is also why many experts recommend putting your baby to sleep around 7-8PM).

The flip side is letting your baby sleep too much. Many times, babies begin life with their days and nights mixed up…thus the increased nocturnal activity. A great way to combat this is to ensure that your baby never sleeps for more than two hours at a time during the day (obviously this is an estimate). Yes, this means that sometimes you will actually have to wake your baby up! This is critical though, especially during the newborn days.

The big takeaway here is this:

1. Get your baby to fall asleep at just the right time–right when she shows signs that this sleep window is open

2. Ensure that your baby doesn’t sleep the day away.

(If you’re confused about how much sleep is appropriate for your baby’s age, you can check out this article). 

5. Physiological Hindrances


I don’t know if I’m not empathetic or observant enough, but it’s always difficult for me to tell what physical ailments are preventing little girl’s sleep.

 The absolute worst is teething. I mean, when aren’t babies teething? You’ve probably seen the symptoms: drooling, pulling at the ears, gnawing on everything, fussiness, light fever, etc.

Teething is a super tricky issue, since it is a legitimate reason why your baby won’t sleep, but there’s not a ton you can do about it. Do what you’ve got to do, but be careful about forming poor sleep habits (like sleep props).  It’s easy for parents to use a sleep prop once in desperation and create a habit out of convenience later.

These two tend to go hand-in-hand. If your baby is under 4 months, has wet burps, constantly spits up, projectile vomits, or seems like he’s in pain after feeding, have him checked out for GERD. If your baby’s esophagus is burning up, there’s a good chance that’s why your baby won’t sleep.

Having said that, GERD does not have to equal sleepless nights. Yes, it makes it difficult, but you absolutely can have a great sleeper with a GERD baby.

My daughter suffered from horrible gas and reflux during her first couple months. We continued on with our schedule ( her predictable feeding pattern allowed her body to cope better) and tried different methods to ease her discomfort. Like many other moms, we found solace in the Rock n Play and Gripe Water (to get rid of the gas). 

Wonder Weeks & Growths Spurts

Growth spurts and developmental leaps can disrupt everything. Over time, you’ll notice that your baby goes through predictable fussy periods. All of a sudden your perfect angel is crabby, can’t sleep worth a crap, and then suddenly simmers down a few days later.

These periods, according to the book Wonder Weeks, are caused by developmental leaps. Basically, your baby’s body, brain, and senses are growing and changing, causing several disruptions. For example, if your baby is learning how to roll over, her favorite time to practice will probably be at night or during naps.

If that wasn’t bad enough, your baby will go through predictable growth spurts about once a month (with major ones at regular intervals as well). Your baby’s bones ache, she’s hungrier, and she’s clingy. Total drag for baby sleep.

Unfortunately, there isn’t a ton you can do. Just be patient, stick to your guns, and ride it out.

7 Surprising Things that Can Ruin Your Baby's Sleep - Baby Sleep Tips

Sound is a double-edged sword. Too much sound and your baby will undoubtedly wake up. Not enough sound and your baby will wake up at the sound of a pin dropping. Many moms advocate using a white noise machine to help with this issue.

Also, different sounds have a funny way of stimulating your baby.

Cali will wake up from naps early when she hears a door open, my voice, or my cell phone. She’s associated these sounds with naptime being over. But I’m telling you the kid can straight up sleep through gunshots (true story), my husband loading the car with tires, and sanders.

My advice: try different things. If you use my Sleep Troubleshooting Checklist, make sure you take note of any sounds nearby when your baby wakes early. I think you’ll begin to notice a pattern.

7. Crib and Mattress Choice

When I bought my baby’s infant mattress, I felt a little guilty. It was so hard! But SIDS is nothing to mess around with. Despite how hard I thought the mattress was, it’s never disturbed her sleep.

In fact,  my daughter slept significantly less in her Pack n Play. Don’t get me wrong, I loved the Pack n Play. It was an excellent and inexpensive choice for a bassinet. But, the mattress was much less supportive, shifted when she moved and was quite noisy.

Here’s my point: when you’re trying to nail down why your baby won’t sleep, you must leave no stone untouched. Test your baby’s mattress. When you apply pressure, does it shift? If you’re using a bassinet, are the support pieces creating a bump in the mattress? This is such a small thing, but like us, babies can get uncomfortable.

8. Sleep Props

Just a heads up, this is a long section, but that’s because I have dealt with this issue extensively. I will be getting more into sleep props later, but since this is such a huge disruptor of sleep, we’re going to sit here for a while.

If you’re searching for reasons why your baby won’t sleep at night, you’ve probably already heard that sleep props can be the devil!

Here are just a few examples of a sleep prop:

  • The “evil” pacifier
  • White noise
  • Rocking
  • You
  • Swaddling
  • Nursing/Bottle

Let me sidetrack a minute here to share my own sleep prop experience. When my daughter was born I was hard-core against sleep props. My ultimate goal was to ensure that my daughter could fall asleep on her own wherever and whenever. Then, I read the Baby Whisperer Solves All Your Problems, and discovered the importance of infant suckling. In case you haven’t heard, babies have a physiological need to suckle, especially the first couple months. Not to mention, a pacifier, if used properly, can be an excellent sleep training tool. So, I let her have a pacifier.

Aaaand, she got addicted.

It was 100% my fault that the pacifier turned into a sleep prop. The experience was terrible. I debated with my husband every single day if I should wean her off it. Simply put, sleep props kill your baby’s sleep.

What I learned from this experience:

  • If your baby can’t go to sleep without something, he has a sleep prop. I lied to myself every day, saying that I chose to give her the pacifier. She’d be fine without it. Yeah, right.
  • When your baby has a sleep prop, you may believe that it’s essential to their sleep, but it’s actually killing it.
  • A sleep prop is more about you than your baby. Think about it. Your baby didn’t ask for the sleep prop. You gave it to him so he would sleep. It was convenient, you didn’t know what else to do. The end result was an addiction. Sleep props, inevitably, are a parenting issue (the Baby Whisperer calls it “accidental parenting”).
  • Don’t delay in weaning your baby from it. Take a good hard look at why you have hesitations for weaning. If it’s not practical (teething pain, you’re on vacation, baby is sick, etc.), then apply some of the sleep training tips (many are no-cry methods!) in my last post and take care of the issue.

9. Random Environmental Contributors


I’m not saying the room has to be pitch black, but especially in the early days when your baby’s circadian rhythm is still developing, light can be a catalyst for early wakings. In addition to brightness, analyze what kind of light is in the room. Babies don’t need a nightlight. So, unless you need it for yourself, you can nix it. If you do need a nightlight in the room, try to look for a warm/red hue. Research indicates that blue lighting can disrupt sleep. 


Like adults, the temperature can be a sneaky reason why your baby won’t sleep. The ideal temperature for your baby’s nursery is between 68-72 degrees.

Keep in mind that this is just a general statement. Like me, my daughter runs a bit cold. If her room edges toward the 71 degree mark, I can almost count on her waking up early.

(If you’re like me and your baby’s room doesn’t have a thermostat, I found this video baby monitor very helpful. For the most part, the temperature readings seem to be accurate and it’s blessedly cheap!)

Also, keep in mind your baby’s clothing. Some babies like their feet covered when they sleep. Others hate it. Some like sleep sacks, others prefer their legs to be open. It takes some trial-and-error, but once you solve this sneaky issue, you can eliminate your baby sleep problems.

10. Breastfeeding

Yep, I said it. Sometimes, breastfeeding can be one reason why your baby won’t sleep (This is coming from a breastfeeding mama, so bear with me!).

You’ve probably heard that breastmilk metabolizes faster than formula. Typically, a formula-fed baby, (ruling out all other factors, like weight, illness, etc.) does not need to be fed as much as a breastfed baby. In the early days, this can translate to longer hours of sleep.

When you consider other breastfeeding-related factors, such as low milk supply, hindmilk/foremilk imbalances, not being able to measure how much your baby is drinking, and tongue tie, formula-fed babies can have the edge.

Like genetics and physiological hindrances, breastfeeding does make sleeping through the night more difficult, but it doesn’t prevent it. You may have to make certain adjustments to ensure excellent sleep. (Remember, my baby sleep continuously 5-6 hours through the night by 8 weeks).

I go more into this in my upcoming post,  but I believe the key to successfully getting your breastfed baby to sleep through the night is:

  • Full Feedings
  • Consistent Feedings
  • The Dreamfeed

Once You Figure Out Why Your Baby Won’t Sleep, You Can Fix It!

So…are you feeling overwhelmed? Can I be 100% honest? I still feel overwhelmed too!

A baby sleep problems are not as clear-cut as people would have you believe. You can’t just adjust one thing or tinker with another and have an instantly sleeping baby (okay, some people can.) In fact, sleep is such an important and tricky issue, that in Australia, they actually have sleep clinics to train parents to sleep train their children. 

So, please, do not feel bad.

You can figure this out and I’m definitely not going to leave you high and dry.

The first step is to identify why your baby won’t sleep. There could be multiple factors at play. Sometimes, you need to become somewhat of a mad scientist. Bunker down and conduct experiments, keep a sleep journal, whatever! Do this for a few days and I’m sure you’ll  find a few nasty patterns.

If this sounds a little exhausting, I totally get it.

I created this sleep troubleshooting checklist to streamline the process. I made this for myself (and still use it) because I didn’t have time to write down every detail. This worksheet was a life-saver.