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Night sleep guide · United Kingdom

Baby won't sleep at night: 7 causes to check first

When a baby will not sleep at night, parents often feel they have tried everything. In practice, there are usually a few predictable reasons worth checking first.

Key takeawayA practical checklist to help you identify what may be keeping your baby awake at night.
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1. The last wake window is off

If bedtime comes too early or too late, sleep pressure may not be right. Look at your baby’s age, naps and evening behaviour.

2. Daytime sleep is unbalanced

Some babies are genuinely overtired. Others have too much daytime sleep or a late nap that pushes bedtime back.

3. Bedtime depends on one specific help

If your baby only falls asleep feeding, rocking or in arms, they may ask for the same support again between cycles.

4. There is a temporary regression or developmental burst

Milestones, teething, illness, travel and routine changes can all disrupt sleep for a while.

Important: baby sleep varies enormously. Avoid one-size-fits-all promises, and always prioritise feeding, growth and safe sleep advice.
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.

Want to know what is disturbing your baby's sleep?

The Petit Nuage sleep quiz looks at age, naps, night waking and settling habits to show you what to focus on first.

Take the 2-minute quiz →

Frequently asked questions

Why is my baby suddenly fighting sleep at night?

A change in age, naps, bedtime timing or development can shift sleep very quickly.

Should I let my baby cry?

No. You can make changes gradually and still respond to your baby.

How long should I test one change?

Give it several days when possible so you can see a pattern rather than one random night.

Reference sources: NHS baby sleep guidance · The Lullaby Trust safer sleep information. Last updated: 24 September 2026.