Why sleep changes now
Around four months, sleep cycles mature. That can make your baby’s sleep look lighter and more interrupted.
What to focus on
Protect daytime sleep, keep bedtime age-appropriate and avoid making too many changes at once.
Stay realistic
You do not need a perfect routine. Aim for a calmer, more manageable pattern instead.
Important: every baby's sleep is different. Avoid one-size-fits-all promises, and always put feeding, growth and safer sleep first.
Safer sleep reminder. For babies, use a firm, flat sleep surface and follow the latest safer sleep advice from the NHS and The Lullaby Trust.
What's affecting your baby's sleep?
The Petit Nuage Sleep quiz considers your baby's age, naps, night waking and how they settle, helping you work out what to focus on first.
Take the 2-minute quiz →Ready to get started?
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Frequently asked questions
How many naps should a 4 month old have?
It varies, but several naps are still normal.
Why did sleep suddenly get worse?
This age is well known for temporary sleep disruption.
Should I change everything now?
No. Start with small, high-impact changes.
Reference sources: NHS baby sleep guidance · The Lullaby Trust safer sleep information. Last updated: 28 October 2026.