The four-month sleep regression
Around four months many babies who had settled into longer stretches start waking more at night and taking shorter naps. It is common, it passes, and a day planned around your baby’s wake windows makes it easier to get through.
What changes
Around this age a baby’s sleep starts to look more like an adult’s: lighter and deeper stages take turns through the night and through each nap. Between those stages a baby comes close to waking. One who fell asleep being fed or rocked may look for the same help each time, so a night that used to have one waking can suddenly have several.
Nothing has gone wrong. Many parents describe it as sleep going backwards, which is where the name comes from, but it is a step forward in how sleep is built.
The wake window moves too
In Rytmi’s age-based starting points the wake window grows from 1 hr 35 min to 2 hr 5 min around four months. A nap routine that worked last month can suddenly be too early: a baby who is put down before they are tired enough may fight the nap or wake from it quickly. See the numbers and a next-nap calculator for a 4-month-old.
What tends to help
- Watch the window, not only the clock: start winding down when your baby plays more slowly, rubs their eyes or turns away.
- Keep one short, familiar routine before every sleep, so the signal is the same by day and by night.
- Protect the evening. An overtired baby often has a harder night, so an earlier bedtime for a few days can be worth trying.
- Keep a log. A few days of entries show whether naps are shortening, whether night wakings cluster at certain hours and whether the windows have moved.
How Rytmi helps
Rytmi starts from the age-based wake windows and, after a few days of logs, works from your baby’s own naps and wake-ups. The next nap it shows moves with your baby through changes like this one.
- The next nap and bedtime, worked out from your own entries
- One shared log for everyone who puts the baby down
- Free, with no ads
When to talk to your pediatrician
If your baby seems unwell, feeds less than usual, or you are worried about how they sleep, talk to your pediatrician. A regression is about the shape of sleep, not about a baby who seems ill.
See the next nap coming
Log a few naps and feeds, and Rytmi starts showing your baby’s own wake windows instead of averages.
Rytmi is on iPhone for now. The Android app isn’t on Google Play yet.
For iPhone · free · no ads
This page is for planning the day and is not medical advice. For questions about your child’s health, sleep and development, talk to your pediatrician.