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4 Month Sleep Regression

The Sleep Nanny refers to the 4 month developmental phase or leap as the “4 month fussy phase.” You may have already heard about this phase which is also commonly referred to as the 4 month sleep regression, but in reality it is all about forward development. So, as I’m sure you’ve guessed by the title, this developmental period may send your little one into a bit of a sleep spin but it is NOT a ‘regression’ of your baby’s ability to sleep.

Some indicators that you’re experiencing the 4 month sleep regression are:

  1. Increased fussiness
  2. Multiple night wakings (especially if your baby has just begun to sleep longer stretches during the night)
  3. Reduced naps or “disaster naps”
  4. Changes in appetite

 Recognising the 4 Month Sleep Regression

 The bad news? Your baby’s sleep schedule just turned on its head. The good news? This probably means that your baby is growing! You may notice that your baby has outgrown his current clothes, or has begun to increase his mobility (it’s not uncommon for babies to learn to roll over during this time). Parents often can’t figure out why their calm baby is suddenly a sleep deprived, fussy, cranky, overtired baby in what seems like an overnight transition. They begin to question if it could be an ear infection, teething, lack of supply (for breastfeeding mums), or maybe he’s got reflux…the list goes on. What parents don’t often realise is that around this time your baby’s sleep rhythms have also changed. So what can we do about it?

 Infant Sleep Patterns and how a 4 month old sleep pattern is different

 As an infant, your baby probably slept fine just about anywhere and everywhere. This is because while an infant does cycle through sleep, there aren’t distinct sleep stages like an older baby or adult may experience.

Now that your baby is older, she is beginning to enter a more organised world of sleep, which means that she will be cycling in and out of very distinct stages: deep sleep and active sleep, just like you. The problem is that your baby doesn’t know how to deal with this new sleep cycle, so if you’re rocking or feeding your baby to sleep, you may find that it takes a full thirty minutes for them to be fully asleep, only to have your baby wake up, feeling fussy less than fifteen minutes later. This is can be due to the startle reflex which occurs when they enter active sleep, and it often wakes them up, and if they don’t know how to get back to sleep, they look for the person who can help: mum or dad.

As if that wasn’t stressful enough for you, your baby actually does most of her deep sleep at the beginning of the night. So while she may go to sleep for about five hours and this may be considered as sleeping through the night at this stage, many 4 month olds are capable of sleeping longer, and so she may begin to wake at regular intervals later in the night. This is where it gets challenging. Your baby is growing, the world is becoming far more interesting for them, and they have to learn to fall asleep on their own. No wonder your little one is cranky (and you probably are too!) If you’ve experienced this phase, you aren’t alone. Fortunately this fussy phase should only last between two and four weeks; any longer than that, and you’ll have accidentally created a new unwanted sleep schedule for her.

 7 Tips to Help You Through the 4 Month Sleep Regression

  1. Do what works, your goal is to get her to sleep.

The world is changing for your baby, so try to ‘go with the flow’, at least for now. What worked yesterday may not work well today, so be prepared to try a few different options to get her to sleep. If you find you are needing to rock, feed, or pat your baby to sleep, it’s a good idea to start to practice putting her down more awake but this is just practice at this stage as you are not going to create any negative sleep associations that cannot be undone between now and 6 months..

  1. Watch for your baby’s sleepy cues, and try to respond to them quickly.

Depending on your baby, her sleepy cues may be anywhere from subtle to over the top. Watch for things like yawning, disinterest, rubbing her eyes, and increased fussiness. Your baby’s wakefulness window at this age is between 1-2 hours, and her fussiness may mean she is telling you that she needs sleep. When you see these signs, act quickly and help her get to sleep so that she does not become overtired, which will make falling asleep much harder on both of you.

  1. Once your baby’s fussiness begins to calm down, consider introducing ‘drowsy but awake’ at bedtime.

This will encourage and help him learn to put himself to sleep. Stay by his side and offer physical and verbal reassurance. If he does nothing but cry for 40+ minutes despite your soothing help, pick him up and rock, hold or feed him to sleep and try again the next night or whenever you both feel up to it. Don’t be discouraged if your baby isn’t ready to learn to put himself to sleep just yet, as you are only introducing good sleep habits – you are not sleep training your baby at this age. Some babies are more ready than others. Just know that it’s okay to take a break if you’re both frustrated.

  1. Be wary of creating a new sleep crutch. Go ahead and keep whatever crutch is working, but try not to lengthen the list.

This can be hard advice to follow when you are both desperately seeking sleep. If you’ve created a habit of rocking your baby to sleep, keep rocking her, but don’t add feeding her to sleep into the mix. Likewise, if your sleep routine includes feeding and patting, that’s okay, but don’t add rocking to sleep. Lengthening the list of your baby’s sleep crutches just means more work later on.

  1. Offer LOTS of additional snuggles and reassurance.

During the 4 month fussy phase, both you and your baby are likely exhausted so extra snuggles, cuddles and soothing words go a long way. While your baby can’t really offer you reassurance, you can speak calmly to your baby, reassure him, and snuggle with him to help ease him through this developmental change.

  1. Watch for signs of growth.

Yes, this is a trying time, but you’ll be amazed at all of the new discoveries that your baby will make during these few weeks. You may find that your baby learns to roll over, or perhaps she’s beginning to master sitting up. These developmental changes are both exciting and exhausting for her. You may also find that your baby literally grows during this time, as her body is changing and developing, which can lead to her needing even more sleep, so be sure to watch for those sleepy cues and act fast!

  1. Follow your flexible schedule as much as possible.

Babies thrive on consistency and routine, so be sure to provide it. If you haven’t already, this is a great time to create a calm, soothing bedtime routine that consists of 3-4 items (such as book, song, bath, then bed) that you can use before bedtime. You can abbreviate the same routine before naps, cutting out the bath, and choosing just one or two items from your nighttime routine to help your baby learn that it’s time to sleep. Within your flexible schedule, be sure to include consistent feedings so that your baby isn’t hungry, especially if he’s experiencing a growth spurt.

Above all, don’t panic! Your little one is growing and needs your reassurances to get through this developmental fussy phase. If your baby isn’t back to a normal routine after a few weeks, consider contacting The Sleep Nanny for an assessment to find out what is happening and discover how to resolve it in a way that is unique to your child’s needs.


Get fully informed and equipped for this phase so you can help your baby to sleep well and breeze through this tricky time.

Learn More

4 Month Sleep Regression Sleep Nanny Lucy Shrimpton

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