Understanding the 4-month sleep regression
When sleep suddenly changes
By The Millie's Team · Parenting Notes
Around 3-4 months, many babies who were sleeping well suddenly start waking more frequently. This is often called the 4-month sleep regression, but it is actually a sign of brain development.
What is happening
Your baby's sleep cycles are maturing from newborn-style sleep to adult-style sleep. This means they now experience lighter sleep phases where they may wake up more easily.
Is this normal?
Completely. This change in sleep architecture is permanent and healthy. Your baby is not regressing; they are developing.
What helps right now
- Keep a consistent bedtime routine
- Offer comfort when needed
- This phase typically improves within 2-4 weeks