The 4-Month Sleep Regression
Updated
Quick answer: The 4-month sleep regression is a lasting change in how babies sleep, usually between 3 and 5 months. Sleep cycles become more like an adult’s, so babies wake more easily between cycles. It often shows up as short naps and more night waking, and usually settles within 2–6 weeks.
Why it happens
Around 3–4 months, babies start cycling through lighter and deeper stages of sleep, like adults do. Each time they come up between cycles they may wake fully — especially if the way they fell asleep, such as feeding or rocking, is no longer there.
Common signs
- More night waking after a stretch of longer sleeps.
- Naps of 30–45 minutes.
- Harder to settle at bedtime.
- More fussiness during the day.
What helps
- Keep wake windows right for the age — about 1½–2 hours at 4 months. The 4-month sleep schedule shows typical timings.
- Use a short, consistent bedtime routine.
- If it suits your family, practice putting your baby down drowsy for some sleeps.
- Use an earlier bedtime after short-nap days.
- Make the room dark for naps and night sleep.
When to talk to a doctor
If sleep changes come with a fever, feeding problems, breathing concerns, or your baby seems unwell, contact your pediatrician.
Common questions
How long does the 4-month sleep regression last?
Usually 2–6 weeks. The change in sleep cycles is permanent, but most babies settle into a new pattern.
Can the 4-month sleep regression start at 3 months?
Yes. It can appear any time from about 3 to 5 months.