Tools · Sleep
Sleep Regression Checker: Which One Is This, and How Long Does It Last?
Enter your baby's age to see which sleep regression is commonly reported at that point, what it usually looks like, and roughly how long it tends to run.
Enter your baby's age to see what is commonly reported around now.
A regression is a description, not a diagnosis. Bad nights also come from illness, teeth, hunger and a schedule that has quietly stopped fitting. If your baby seems unwell or something feels wrong to you, that is worth a call to your doctor rather than a wait for a phase to pass.
Why These Windows Cluster Where They Do
Almost every commonly reported regression sits on top of a developmental change rather than a sleep problem. Sleep cycles maturing at four months, crawling and standing at eight to ten, language and separation at eighteen — the sleep disruption is a side effect of a brain doing something new, which is why it passes on its own.
That also explains why the ages are approximate and why some babies skip one entirely. Development does not run to a schedule, and a baby who crawls at six months may have their "eight-month" regression early. Use the windows as a way to recognise a pattern, not to predict one.
Frequently Asked Questions
How do I tell a regression from something being wrong?
Regressions disturb sleep and leave the rest of the day mostly intact: feeding, mood and temperature stay normal, and the baby is still themselves awake. Illness usually shows up somewhere else too. If your baby is off in ways that go beyond sleep, treat it as illness first and a phase second.
Should I change anything, or just wait?
Mostly hold the routine and add support rather than rebuilding the approach. Regressions are a bad time to start sleep training and a good time to check that wake windows still fit, since a schedule that has quietly outgrown itself will look exactly like a regression and will not pass on its own.
My baby has never had one. Is that a problem?
No. Plenty of babies pass through these ages without a noticeable disruption, and it does not mean development is being missed. The list describes what is commonly reported, not what should happen.
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