How to Master the ‘4-Month Sleep Regression’

Many of us think of sleep as relatively simple – you’re either asleep or you’re not, but it’s far more complex and there are many reasons to explain why some little ones may struggle to sleep. 

The benefits of good quality, consolidated sleep, are huge and we know sleep is vital for your little one’s growth, health and brain development. 

We’ve teamed up with sleep consultant Jenna Wilson from Little Dreams Consulting, to understand baby sleep cycles and how their sleep patterns evolve around that 4 month mark, otherwise known as the ‘4-month sleep regression’.

Understanding newborn sleep cycles (up to 12-16 weeks old)

Newborns actually only have two stages of sleep and spend around half their sleeping hours in deep sleep and half in REM (‘dream’) sleep.

This makes sense as deep sleep is where hormones (including hormones which make them grow) are secreted and REM sleep helps development and regulation of emotions, which can help little ones ‘make sense’ of their day and new experiences. 

At around 12-16 weeks they will transition to sleep cycles that they’ll follow for the rest of their lives – and it is at this point that parents notice a change in their sleep patterns that is also be referred to as the ‘4 month sleep regression’.

The 4 stages of sleep after 12-16 weeks

Stage 1 of non-REM sleep is that familiar sensation where you can just feel yourself drifting off, but don’t feel as if you’ve fallen asleep properly, a very light stage of sleep. Babies may seem to stare into the distance in this lightest stage of sleep.

Stage 2 of non-REM sleep is still light sleep but where people tend to realise, once woken up, that they were actually sleeping.

Stage 3 & 4 of non-REM sleep are deep and restorative. This is where your little one starts repairing and rejuvenating their immune system, muscle tissue and energy stores – and this is also where they grow!

REM (dream) sleep is where the brain becomes much more active, consolidating information and memories from the day, helping development and emotional regulation. This is also the stage where most of our dreaming occurs.

Once we’ve gone through these stages, we come close to waking up – and then the cycle starts over again until morning. These are the stages of sleep for children and adults alike, and this huge developmental stage is the reason behind the ‘4-month sleep regression’, and also the reason some little ones who have previously slept well, wake more regularly as these sleep cycles last around 45-60 minutes.

How to manage the ‘4 month sleep regression’

The good news for anyone experiencing the “4-month sleep regression” is that it’s not, in fact, a regression at all. A regression is defined as “reversion to an earlier mental or behavioural level,” and this is actually the opposite of what your baby is experiencing, your baby is going through a huge developmental stage.

We know how desperate new parents are to get baby back on track with their sleep, so here are some of my top tips I share with my clients to help support their babies during this developmental stage:

1. Try a simple bedtime routine

Stick to around 4 or 5 steps and try to prevent your baby falling completely asleep during their feed. Sing a song or share a story towards the end of their routine to help settle them. Their routine should take no more than 20 – 30 minutes, and your little one should be awake when you pop them down in their cot.

2. Be consistent with all sleep situations 

If you have decided to help your baby learn independent sleep skills from around 4 ½ - 5 months old, you need to be consistent with your approach, so they don’t become confused. Make sure all caregivers are on the same page and using the same routine.

3. Get your timing right

If your baby is getting fussy before bedtime, you’ve probably not quite managed their awake windows (the number of hours between sleep).

Here’s a handy breakdown of awake windows based on age. All babies are different, so try to understand your baby’s unique patterns; you can use this information here as a rough guide.

4. Make your baby’s room as dark as possible

Fear of the dark is a learned fear (learned around ‘toddlerhood’), so your little one is unlikely to be afraid of a dark room. Babies are, however, very responsive to light as, once they are over 4 months, they will be developing melatonin, so try to keep the room they are sleeping in as dark as possible for naps and bedtime.

5. Mask unwanted sounds

You may find that noises startle and wake your little one more easily, once they have developed sleep cycles. Instead of trying to maintain an unrealistic silence, try blocking unavoidable sounds with a white noise machine.

Remember, safety is our main priority when it comes to sleep - the Lullaby Trust are the go-to advice centre for all things sleep safety so, if you are not sure about something check out their website:

The Lullaby Trust - Safer sleep for babies, Support for families

Jenna Wilson set up the multi-award winning Little Dreams Consulting 8 years ago, following 12 years working as a solicitor. She has trained with Sleep Sense™ and The Sleep Charity (UK) and has attended a multitude of courses, including with the NSPCC and The Lullaby Trust.  Personally, she has worked with over 500 families and, in 2022, franchised Little Dreams with her business partner Fay Smith. The franchise is growing and, to date, Little Dreams have helped over 1500 families get a better night’s sleep.