Baby Insomnia or Split Night: Why It Happens and How to Fix

Baby Insomnia or Split Night: Why It Happens and How to FixBaby insomnia is when your baby is awake in the middle of the night for 2-3 hours at a time. It is sometimes called a “split night” and usually lasts for weeks or months. This post will explain why baby insomnia happens and ways you can fix the problem, based on my 15+ years as a sleep consultant.

What Is Baby Insomnia or a Split Night?

Insomnia is usually defined as the inability to sleep when you are actively trying to sleep. This could mean that it’s hard to fall asleep, hard to stay asleep, awake for long periods at night, or wake up too early in the morning.

Baby insomnia is the same but sometimes occurs when there is a mismatch between how much sleep a parent thinks their baby needs and how much sleep their baby actually needs.

When a parent comes to us with a case of baby insomnia, it usually means the baby is awake for long periods in the middle of the night (2+ hours) and can’t go back to sleep. When a baby is taking too long to fall asleep at night or waking up too early, we don’t typically call that “insomnia.” Same for a toddler stalling.

In most cases, if your baby is awake at night but happy and not crying, this is a good indication they have insomnia.

If your baby is crying when they are alone but awake and happy when you’re holding them, that can also be insomnia for a social child. After all, tossing and turning alone isn’t fun for anyone when you can’t sleep!

This is often called a “split night” because your baby might sleep a long stretch at the beginning of the night, wake up for 1-3 hours, then finish their nighttime sleep. They are “splitting” the night into two long fragments.

What About When Baby Falls Asleep In Your Arms But Wakes Up When Put Down?

If your baby is falling asleep in your arms but waking up when you put them in their crib, we would NOT consider that insomnia. If your baby will only sleep in your arms or on your chest, this is usually a case of sleep associations, not insomnia.

Why Is Insomnia Bad?

The reason this is an issue is because it’s not as restorative for your baby’s sleep, in general, and can cause problems with their schedule. It can also cause your child not to get enough sleep in a 24-hour period. And, just like adults, they can feel tired during the day.

So, why does insomnia happen in babies?

Top 5 Reasons for Baby Insomnia

There are 5 primary reasons for long night-waking in children:

  • Developmental Milestones and Sleep Regressions – The most notable reason your baby might wake up for long periods at night is that they are working on a new skill or developmental milestone. When our minds are very busy, we have trouble sleeping (obviously). For adults, it’s often due to something about which we’re stressed or worried. For babies, it might be a new skill they’re learning. During some developmental periods, you’ll also notice a sleep regression.
  • Scheduling Problems – Besides developmental leaps, a scheduling problem is the most common reason for insomnia. But, it can be complicated to fix this. I’ll explain below.
  • Medication Side Effects – Although it’s rarer, there are occasionally children on medications that have a side effect of insomnia.
  • Allergies and Milk Intolerance – In a small number of cases, milk intolerance is to blame for sleeplessness and other allergies.
  • Sensory Processing Disorder – Sensory Processing Disorder (SPD) can also cause insomnia in babies and toddlers. This was the case for one of my clients with a 3-year-old at the time. He would wake up for 1 to 3 hours every single night. In the end, a weighted blanket was the only thing that helped. SPD makes it difficult for children to process information from their senses and then respond appropriately. Typically, one or more senses over- or under-react so it isn’t difficult to see how that could impact sleep.

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What About Teething and Illness?

Teething and illness can both cause discomfort and thus, sleeplessness. However, this is typically short-lived. And, by the time you are wondering if your baby has insomnia, it’s usually over. Therefore, I didn’t include them in the list. Babies get teeth on and off for 2+ years. If they have night-waking related to teething, it’s usually when the tooth is cutting through the gums and then it’s over. That typically takes 3-5 days per tooth. In some cases, they might get two at the same time or back-to-back but even then, it will typically last two weeks or less of sleeplessness (with some nights being better than others.) Insomnia typically lasts several weeks or months.

Ways to Fix Your Baby’s Insomnia

For the purposes of this article, we will be sharing how to fix insomnia when it’s a scheduling problem. For any potential medical or development issues, please see your medical provider.

If your baby has had insomnia for weeks or months, you probably want to fix it. I say “probably” because in some cases, a split night isn’t the worst thing in the world. If your baby is happy and thriving, it may be a phase they go through until they are ready for their next schedule, for example. If it’s keeping you up at night, consider changing your own sleep environment to combat it rather than changing theirs.

However, if your baby seems exhausted during the day and/or is not thriving, you should definitely address the issue. But, how do you fix insomnia?

If it’s due to a sleep regression, you typically need to ride it out. Although there are sleep regressions at various ages, we find that insomnia occurs most during the 8 to 10-month sleep regression and during the 18-month sleep regression in our experience. During other sleep regressions, we notice frequent night-waking but not necessarily long periods of non-sleeping.

Scheduling Problem Tips

When insomnia is due to a scheduling problem, thankfully, there are things you can do to fix it! Unfortunately, it can be one of the most challenging sleep problems to fix. Here are a few tips:

  • Too Much Daytime Sleep – This is probably the easiest scheduling problem to solve. If your baby is older than 6 months old and napping longer than 2 1/2 to 3 hours during the day, we typically need to reduce the amount of daytime sleep. Note: You don’t have to reduce it if there isn’t insomnia. This is only if it’s causing an issue at night. When your baby is sleeping too much during the day, they might not be sleepy enough at night to stay asleep. They might fall asleep fine at bedtime (or not), but they simply can’t stay asleep.
  • Bedtime Is Too Early – You might know about wake windows so you put the baby to bed at night after their appropriate wake window. Great! Only sometimes this can cause split nights. For example, your baby naps from 2 to 3 PM and can stay awake 3 hours. So, you put them to bed at 6:00 PM. Unfortunately, this can cause split nights.  because while early bedtimes are good, your baby’s internal clock might be set for “nighttime sleep” from 7:00 PM to 7:00 AM, for example. If their bedtime is too early, they treat bedtime more like a long nap than bedtime. This happens to adults, too. We see this happen to babies most when they are transitioning from two naps to one nap
  • Too Long In Bed – Similar to bedtime being too early, another issue is what Dr. Ferber calls the “Too Long In Bed Problem.” Essentially, you have your baby in bed for more hours than they are capable of sleeping. If this is the case, you need to try to have your baby in bed for just the right amount of hours. The amount of sleep in a 24-hour period will stay relatively constant. If your baby needs 13 hours of sleep a day, naps for 3 hours, and is in bed for 12 hours, they will likely be awake for two hours in that 12-hour period. This might be at the beginning, the end (early waking), or in the middle (split nights.) To fix this issue, “squeeze” the sleep together by setting an appropriate schedule with the right number of hours for your baby.
  • Overtiredness – Overtiredness can be terrible for your baby’s sleep but usually, it causes frequent night-waking, not insomnia. In some cases, though, it can cause insomnia. Our bodies release hormones (cortisol) to fight fatigue and give us a “second wind.” If we go to bed overtired, we might wake up restless and unable to sleep. In my experience, babies who have insomnia due to this reason are fussier at night than for the above reasons. They are quite miserably tired.


As I mentioned, insomnia is one of the most challenging sleep problems we face as parents and as sleep consultants. Although it should feel simple to put your baby to sleep when they’re tired, there is a bit of an art form to it. When we work directly with families, we typically keep a sleep log while fine-tuning the schedule. This allows us to accurately see the primary cause of insomnia. If you try to solve the wrong problem, you can make sleep even worse! Give a few things a try for 2-3 days and then make more adjustments. If you get stuck, feel free to reach out to us!

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Solve Your Child’s Sleep Problems by Dr. Richard Ferber

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