What Is the 4-Month Sleep Regression?
1 min read Published 3 Jun 2026
By Georgia Hayward, Certified Infant & Toddler Sleep CoachWhat's Actually Happening
Around four months of age, your baby's sleep begins to mature and becomes more like that of an adult. Their circadian rhythm (body clock) becomes more established, and they start producing higher levels of sleep-regulating hormones such as melatonin.
At the same time, they begin moving through different stages of sleep, including lighter and deeper sleep, rather than the simpler sleep patterns seen in newborns.
As a result, many parents notice more frequent night waking, shorter naps, increased fussiness around sleep, or a baby who suddenly seems harder to settle.
It's a Progression, Not a Regression
Although it is often called the "four-month sleep regression", many sleep coaches prefer the term sleep progression because your baby's sleep is developing rather than regressing.
This is a positive and important developmental milestone. The good news is that this stage is a sign of healthy development.
While every baby is different, understanding what is happening can help parents respond with confidence and adjust their expectations during this period of change.
If frequent night waking is affecting your family and you're ready to make a change, my Signature 1:1 Sleep Plan (£300) includes a personalised sleep plan, 60-minute consultation and three weeks of WhatsApp support.
Quote PARENTBOOST when you get in touch at info@tenderlovingsleep.com to receive 15% off - that's a saving of £45. Find me on Instagram @tenderlovingsleep.
This article is published by ParentBoost. It was written or reviewed for ParentBoost by the contributor below and edited by our team. It is general information for parents, not individual professional advice.
Georgia Hayward
Certified Infant & Toddler Sleep Coach
Hi, I'm Georgia. Based in Sussex, I am an OCN-certified Infant and Toddler Sleep Coach and NHS Midwife. I've spent over nine years working closely with parents and young children, giving me a real understanding of the challenges that come with early childhood, especially when it comes to sleep. Having experienced sleep deprivation first-hand as a mum, I now provide gentle, evidence-based sleep support tailored to your child's needs through my service, Tender Loving Sleep.
This article is general guidance for parents and carers, not medical, health, legal or other professional advice. Every child is different. If you're worried about your child's health or development, talk to your GP, health visitor or another suitable professional. In an emergency, call 999. For urgent advice, call NHS 111.
