4 Month Sleep Regression



Just when you thought you had things figured, here comes the Four Month Sleep Regression!


Typically starting between 3.5m and 5m, this pesky little sleep disrupter is caused, as with all regressions, by a developmental leap. But, unlike the 8 Month, 18 Month and 24 Month regressions, this is purely related to sleep development. And unlike those other phases, the change that occurs here is permanent.

The Four Month Sleep Regression (FMR) typically sees your little one waking frequently at night and either boycotting naps or only giving you short ones – we’re talking waking every 45mins-2hrs.


The FMR is down to a permanent change in the way that your baby sleeps. Newborns and infants sleep entirely differently to everyone else – instead of cycling in and out of light and deep sleep, tiny babies have a single deep-sleep phase, which is why they can sleep through anything when they’re down. This all changes at four months when babies transition into more grown up sleep cycles.

This is tough for a little one and will be why you’re seeing your baby waking up anything from 45min-2hrs after going to sleep: sleep cycles are all new to them so when they come out of their initial deep sleep into the lighter part of their cycle, they’re likely to wake and will need help getting back to sleep.

Everyone wakes at the end of a sleep cycle but as we’re well practised, we’re able to settle ourselves back into the next cycle without noticing. For a little one without that self-settle skill (just about every 4 month old) it will be impossible for them to settle themselves well enough to get back to sleep. That’s where you come in.


I wouldn’t advise starting any kind of training when that sleep regression kicks in. What I would suggest is to follow these tips and know that this will pass!

Keep doing what you’ve always been doing: if it’s rocking, feeding or driving your baby to sleep, it doesn’t matter. What matters is that your baby – and you – sleep. Don’t worry that these are potentially detrimental sleep associations for now, you can work on those later. The important thing is that you support your baby through this, help them get as much sleep as possible and you stay sane. That means lots of cuddles and love – for both of you.

Use Movement for Naps: If you’re struggling to get the daytime sleep in, going out in the car or for a walk should do the trick. Sleep breeds sleep and at this age you’re aiming for around 3hrs in total: how this happens during the day isn’t important just so long as it happens.

Use your Wakeful Windows to minimise overtiredness: Work within Wakeful Windows to work out when you should be starting each nap. A Wakeful Window is the maximum amount of time a baby can be awake before they have to sleep – for a 4 month old this is 45min-2hrs. I would recommend that during the FMR, when sleep is so disrupted and your baby likely to be exhausted, that you stick to the lower end and don’t push them too hard towards the top. If that means pre-6pm bedtimes, by the way, that’s perfectly okay – you can push bedtime around by up to an hour without affecting the internal clock and a tired baby going to bed is so much better than an exhausted one.

Ask for help: as a Mum who’s been there, I know that you are going to be worn out by this horrible FMR. Get as much help as you can from your partner, family or friends. Sleep whenever is possible and know that there is hope once this is over.


As things start to ease, think about sleep training. Now’s the time to look at those sleep associations and start weaning your baby off them. The tip is always that a child should be going into their bed ‘drowsy, but awake‘: you’ll hear that a lot in the sleep training world but I cannot emphasise how important it is. Sleep training teaches your child how to fall asleep on her own by giving her the essential life-skill of the Self-Settle. If a baby can’t settle herself when she wakes, she will always struggle to get the amount of quality sleep that is vital to her development. And she will always need you to get her back to sleep.

There are plenty of gentle sleep training methods that are suitable for babies over the age of 18 weeks – I offer specialised, bespoke plans that help parents give their babies the confidence to become independent little sleepers. If you’d like any advice or support in implementing a plan, do get in touch – I’d love to help.

Get In Touch: Lucy Barker Sleep Consultant