The “Split” Night: Why some babies are awake for hours in the middle of the night, and how to change it

(Revised and updated from an earlier version.) 


There may be a time when you find yourself up in the middle of the night for hours with your baby who just won’t sleep!  A split night is easily distinguished from other situations where your baby may be up during the night: it’s persistent, most babies will be in a good mood, and no amount of comforting, nursing, soothing or sleep training will get your baby back to sleep quickly. A split night is largely a biological issue, arising from a dissociation between the sleep drives. If it sounds like your baby is having a split night, read on!

The Science 


There is a maximum number of hours that a child can sleep at night (see our sleep chart here). Consolidated nighttime sleep is driven by two factors: (1) the circadian rhythm establishing a regular bedtime and wake time, and (2) sleep pressure arising from staying awake for an appropriate amount of time during the day. When things are going well, your baby will build sleep pressure during the evening and go to sleep at a regular time. As sleep pressure dissipates with night sleep, the circadian rhythm will take over and keep your baby asleep for his/her maximum sleep duration and wake up at a regular time. That pattern will be fairly stable within about a 30-minute range on either side. When a split night happens, the sleep pressure drive separates from the circadian rhythm. This means that your baby may sleep for 8-9 hours and wake up feeling pretty refreshed and ready to go … at 2am!  Your baby will be up for a while and build up a bit more sleep pressure, and then, as the circadian drive to sleep kicks back in, your baby will sleep for a few more hours until morning. This pattern usually sticks, leaving your baby with hours of happy waking in the middle of every night. If you look at this graphically (the reason we love when parents track sleep!), the problem is usually that your baby has gotten into a pattern of having too many hours in bed every night and is not able to fill that time with sleep.


There are two primary causes of a split night:


1. Split Night Caused by Poor Napping and Extra-Early Bedtimes


This is the most common cause of split night, and it is almost always remedied by schedule changes. There may be times when your baby can sleep more than his or her typical sleep duration. For example, if your baby has had a really terrible nap day, then you might put him/her down early for the night in order to help her catch up on sleep. This is usually a good decision and will lead to a longer-than-usual night of sleep with morning wake time remaining consistent. The reason that an occasional extra-early bedtime works is because of the two sleep drives (more on the basics behind sleep drives here). When your baby accumulates a sleep debt (over-tiredness, a.k.a. high sleep pressure), he or she can go to sleep early but will sleep until his/her normal wake time. This is because the circadian rhythm controls wake time, and it takes a few days to change the circadian bed/wake time. The problem is that, after a few days of an early bedtime, one of two things will happen: either (1) your baby will start to wake up earlier, transitioning back to his/her normal duration of sleep or (2) your baby will develop a “split” night, during which he or she stays in bed for more hours than he/she is capable of sleeping and thus has a long span of time awake in the middle of the night. This is a very common trouble spot for parents who subscribe to the early-bedtime-solves-all-problems philosophy (read more about that here).


How does this happen? 


It’s so easy to get into a bad cycle. For example, your baby might have a poor nap day and be exhausted an hour earlier than normal. In this case, you might put your baby down an hour early to help him or her catch up on sleep, and he/she will likely sleep until a normal wake time. Then, the next day he/she might have another bad nap day, and you might put him/her down early again. Then, another bad nap day and another early bedtime, but by around that third day, your baby's sleep pressure may start to dissipate in the middle of the night, and he or she might be happy, refreshed and ready to go at 2:00 am. You might try to rock, comfort or nurse your baby to get him/her to sleep, but since he or she isn't sleepy, he/she probably won’t sleep for at least an hour. After an hour or so, your baby will feel sleepy again and fall asleep. In the morning you will probably let him or her sleep until normal wake time, or you might even let him/her sleep-in, thinking that you should allow extra sleep in order to make up for that time awake in the middle of the night. If the poor naps early, bedtime and sleeping-in continue, so will the split nights.


2. Split Night Caused by Night Disruption


Sometimes a split night can happen because your baby’s sleep gets disrupted during the night. Sometimes this is a result of learning new motor skills (standing and crawling are fun and exciting activities!). Sometimes it arises from illness (e.g., holding your baby for an hour in the middle of the night in a steamy bathroom to alleviate congestion). Sometimes it can arise from stimulation after feeding or sleep-association interactions.

So, How Do I Fix a Split Night?


Solving a split-night problem due to nap problems is not at all intuitive. You’ll actually need to restrict your baby’s time in bed in order to ensure that sleep is achievable for the amount of time he or she spends in bed. You would probably never dream of waking your baby in the morning, especially when you are exhausted too, but in most cases you will need to wake your baby in order to maintain a consistent wake time with morning light exposure (light “locks in” the circadian drive to sleep). You will probably also have to manipulate your baby’s naps, so that she is able to make it to bed at a regular, slightly later time at night. As with most problem solving, it usually helps to work through an example:


Imagine that your baby is 11 months old and naps poorly at daycare, with a 45-minute nap at 9:00 and a 45-minute nap at 1:00. As a result, you put your baby to bed at 6:30pm each night, because she is exhausted. She falls asleep on her own in the crib and sleeps until about 2:00am, eats and is awake for an hour and a half, then she goes back to sleep and wakes up for the day at 7:00.


At 11 months, most babies need 3 hours of naptime and 10.5-11 hours of sleep at night. In this example, the poor naps are necessitating the early bedtime, but this child isn’t capable of sleeping for the full 12.5 hours she is in bed at night. This means that when she wakes up for her feeding, she feels rested and good to go. It isn’t until her circadian drive kicks in and she builds a little bit of sleep pressure that she can sleep again. If short naps keep happening, your baby will stay stuck in this pattern.


To fix this, you’ll need to shift your baby’s bedtime a little later, to around 7:15pm, and wake her a little earlier in the morning, at around 6:15. In other words, you’ll need to condense her night. For your baby to make it to this later bedtime, you’ll HAVE to work on naps. In this example, you might need to start on the weekend when you are home with your baby, so that you can get her back on track by increasing her daytime naptime. You’ll also want to work with your daycare provider to see if there are things they can do to help increase your baby’s sleep duration. Rocking, holding, extra soothing, and feeding may all be useful tools to help facilitate extra daytime napping while solving a split night problem.

Common Questions


What does the night look like with this type of scheduling intervention? 


Your baby will almost certainly still wake for a long time during the night for a few days following the schedule restriction. This is because it will take his or her sleep drives time to merge together again. You can expect that things will go back to normal in 4-7 days if you are consistent with the schedule adjustment. If your baby persists with short naps for unavoidable reasons at home or daycare, he or she may benefit most from an early-bedtime schedule twice per week, such as Tues/Friday bedtimes 1 hour early. This will help prevent an accumulation of too much sleep debt WHILE ALSO avoiding the split-night scenario.


What if my baby naps ok, but is practicing motor skills during the night? 


You should follow the schedule restriction as described above, by shortening her night. Give her lots of time to practice new skills during the day, and at night remind her of what she needs to do to get into a comfortable position for sleep. For example, you might just keep patting the crib mattress and helping her lie down. Try not to do all of the work for her, because you don’t want to fix one problem only to create another.

If this happened due to illness, when your baby is feeling well, begin the schedule restriction as described above.


What if my baby is just excited after feedings or soothing? 


First, try to figure out whether or not your baby needs to eat at night. If your baby is older than six months, you can ask your pediatrician about whether he or she is old enough to gently guide out of night feedings (some babies will be ready, some won’t). See our blog about reducing night feedings here. If you get the green light to rebalance her calories to daytime, then you will effectively eliminate the cause for her long waking. Once you restrict her bedtime as described above, she should start sleeping better. If it's too early to drop the feeding, then stick to your nighttime parenting behavior at night. Go and feed your baby, but keep the lights off and keep your interactions gentle and as brief as you can. After the sleep restriction, he or she should extend her sleep further. For underlying problems with sleep associations, you may continue to have sleep-cycle wakings every 60–90 minutes (and to change that you would start some sleep training), but the split night problem should resolve.  

We hope that this helps you eliminate your baby’s middle-of-the-night playtime. If you are still having trouble, consider scheduling a consultation with us for personalized support.



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