This Blog is looking at 4-month sleep regression. In the time I have been working with Little Dreams this is the question that I have been asked the most so I thought it would be beneficial to share some information to support families and provide some useful tips.
Developmental milestone
Through my journey of learning I have discovered that the 4 month “sleep regression” is not about babies moving backwards but it is actually when their sleep takes a huge step forwards. Around this age babies have a developmental leap as well as a growth spurt and all of this can cause disruptions to sleep.
Sleep cycles
Until around 4 months, babies have a very random sleep pattern, see my blog on Navigating the early weeks for more information. Around 12-16 weeks, the point of the 4 month sleep regression, babies start to develop sleep cycles that will stay with them throughout their adult life and their sleep becomes more structured. Therefore, it could be argued that we should be calling it the 4 month progression, not regression!
At this age babies will start to develop sleep cycles of around 30-60 minutes which then extend to around 90 minutes as an adult. They also now have 4 stages of sleep, as opposed to two as a newborn..
Different stages of sleep
All stages of sleep are important, but they do very different things!
Stage 1 and 2 are light (known as REM sleep.) This is where your baby dreams and process things that have happened during their day. Think of it as their internal filing system – ready to take out when they next need it. Deep sleep, stage 3 and 4 (or NREM sleep), is restorative, their growth hormone is released and their immune system kicks in.
So how do deep sleep and light sleep change during the night? Why is this important for understanding babies sleep? The first part of the evening will now shift to include a period of really deep sleep. This can be 2-3 hours depending on your little one. During this time, they are unlikely to wake up, even with low level noise around them.
This is then followed by cycles of lighter sleep, often starting around the time parents go to bed. With this increase in lighter sleep, for babies who struggle to fall asleep independently it unfortunately can mean an increase in night wakings, the reason for this is explained below.
At the end of each cycle, when babies come into this lighter stage of sleep, they have a mini awakening. If everything is as it was when they went to sleep, they think “ok, everything is fine” and are likely to go back to sleep. However, if they wake up and things are different to how they went to sleep, they think “what’s going on, why do they think I don’t want to be rocked any more, I don’t like this” and may then protest until balance is restored. So, for example, if they are rocked, fed or bounced to sleep, when they wake up and this isn’t happening any more, they may struggle to get back to sleep.
This is where some parents can see their little one waking every hour during the night which is exhausting and unsustainable.
How do I know they are having or passed this regression?
All babies are different, and you may see no change in their sleep, however here are some indicators:
- Difficulty falling asleep.
- Increase in night wakings
- A decrease in total sleep time.
How can I help navigate the 4 month sleep regression and top tips!
There are some great habits that you can start to introduce before the 4 month mark. This can help your baby before, during and after this phase.
- Make the room as dark as possible. Children do not develop a fear of the dark until around 2 and a half. However they are super sensitive to light. Light tells their brains that something is happening and they should wake up. So make the room as dark as possible.
- Establish a good routine early on and keep this consistent.
- Start off with some quiet play in a darker room.
- Move to the bathroom and have a wash or bath. Clean those teeth if they have already got them!
- Pop them in their bedtime clothes.
- Have a feed and try to keep them awake.
- Enjoy a lovely story.
- Place them on their back to go to sleep completely awake, following safer sleeping advice from the Lullaby Trust.
- Make sure baby isn’t overtired. Use awake windows to make sure they are getting the right amount of awake time between sleeps. An overtired baby finds it much harder to get to sleep.
- If you have a noisy household, consider white noise. As your baby will be spending more of their time in light sleep, they may be more aware of noise. If you do choose to use white noise, make sure it is on consistently whilst they are asleep, not just at the start of the night!
This period of development generally only lasts a couple of weeks. However, with any child related development, it can be shorter or longer.
If your little one is over 4 months and you are still struggling with a lack of sleep, we can help. See how we can support you with our Child in a Cot package.


