Causes of Split Nights and How to Fix Them

morning/night wakings regression Jan 10, 2023

So first of all, what is a split night?

Well simply put, it is when your little baby (or toddler) wakes in the middle of the night for a LONG period of time and won’t or can’t go back to sleep. This could be up to a few hours or so. 

During this waking your baby could be very upset and hard to console, OR they could be totally wide eyed and happy as a clam. And I’ll go into this a little bit more later, but this will help you to determine WHY it is happening and HOW to resolve it. 

Consolidated sleep overnight is powered by your baby’s circadian rhythm and sleep pressure. We as humans only need a certain amount of sleep every night/day (for babies this is about 10-13 hours a night plus naps). If for some reason there is some imbalance in that, then you may experience a split night. The reason for the name “split night” is just because the night is split into two parts with awake time, basically. 

Now it’s important to understand that split nights do not require a  “sleep training” type of resolution. The reason they are up in the night is not often because they don’t know how to fall asleep on their own (unless, perhaps, this is true, in which case I suggest learning more about sleep teaching here). The typical reason for the split night is that they are physically unable to fall back to sleep due to insufficient sleep pressure. 

Alright, we’ve established WHAT it is now, but why does it happen?!

This question is a little bit trickier to answer because there are a few common culprits rather than just one reason or one quick fix, but let’s discuss the main ones:

  1. Under-tiredness

    Too much daytime sleep may be causing your baby to simply not need to sleep for as long overnight, and needing MORE sleep pressure to get back to sleep. Hence that LONG waking to build up the sleep pressure. You’ll usually find that your baby is totally happy, clappy and wide eyed during these wakings. To resolve this, re-evaluate your baby's naps and awake times. Are they ready to drop a nap? To help you determine this, check out my helpful blog "When to Drop a Nap" here. 

  2. Overtiredness

    The exact opposite of the above, lol. Basically, your baby isn’t napping well, or going to bed early enough, and therefore experiences an increased level of cortisol which makes it really hard to fall asleep and, you got it mate, stay asleep. If this is the culprit of the split night, you’ll likely notice your baby is just upset during the whole waking. Unfortunately, under and overtiredness can be hard to distinguish between. Thankfully, I have a helpful blog to help you do this. Read it here! If you are 100% sure that your baby is overtired, I have a blog called “Breaking the Overtired Cycle” that you will find really helpful here.

  3. Developmental Progression AKA Sleep Regression

     Yes! Normal development can also be a cause of a split night. If this is the cause of your baby’s long night waking, you’ll probably notice that they are practicing a new skill (rolling, sitting, crawling, standing, walking etc.) For more information on sleep regressions, make sure to check out my FREEEE Sleep Regression Mini Course here.

  4. Chronic short naps and subsequent very early bedtime

    If you’re stuck in a rut of short naps and very early bedtimes and you’re having trouble with split nights, this may be contributing to it. If you’ve been here a while you know I’m ABSOLUTELY an advocate for an early bedtime (6-8PM), but sometimes you can get caught up in a cycle of short naps and a very early bedtime before 6:00 PM and it can really shift your child’s circadian rhythm. One of two things will likely happen: Baby will wake up earlier because they get a full 12 hours of sleep, OR they’ll have a split night. Now this is probably one of the trickier culprits to tackle, but no fear, I have a LOT of resources to help. You want to start with the source, encouraging longer naps. If you haven’t already, read my blog “5 Tips for Short Naps” here! If you’re sick and tired of short naps and just want a solid plan to get it sorted, you want the Baby Nap Guide (for ages 0-18 months) to get you on the right track ASAP. Learn more about the Ultimate Nap Guide here.

So there you go, split nights explained and tips to help!

If you’re
constantly struggling with bedtime and night sleep and need help, that’s where I come in. This is my jam! The first thing you want to do is make a clear plan for bedtime. None of this "chuck them in a crib and walk off for 12 hours." A solid sleep plan with several sleep teaching options to fit your comfort level as a parent. YOU choose what works best for your baby and your family 👇



If your baby is under 3 months old


If your baby is 4-24 months old 


If your little one is 2 years +



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Cooney, M.R., Short, M.A. and Gradisar, M., 2018. An open trial of bedtime fading for sleep disturbances in preschool children: a parent group education approach. Sleep medicine, 46, pp.98-106.

Wurts, S.W. and Edgar, D.M., 2000. Circadian and homeostatic control of rapid eye movement (REM) sleep: promotion of REM tendency by the suprachiasmatic nucleus. Journal of Neuroscience, 20(11), pp.4300-4310.

Lee, M.L., Swanson, B.E. and Horacio, O., 2009. Circadian timing of REM sleep is coupled to an oscillator within the dorsomedial suprachiasmatic nucleus. Current Biology, 19(10), pp.848-852.

Khalsa, S.B.S., Conroy, D.A., Duffy, J.F., Czeisler, C.A. and DIJK, D.J., 2002. Sleep‐and circadian‐dependent modulation of REM density. Journal of sleep research, 11(1), pp.53-59.

Czeisler, C.A., Weitzman, E.D., Moore-Ede, M.C., Zimmerman, J.C. and Knauer, R.S., 1980. Human sleep: its duration and organization depend on its circadian phase. Science, 210(4475), pp.1264-1267.


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