Sleep Regression Ages: the Full 4-24 Month Chart

A "sleep regression" is a stretch where a baby or toddler who had been sleeping reasonably well suddenly starts fighting bedtime, waking more at night, or taking short, broken naps — usually with no illness to explain it. The frustrating part is that they tend to arrive right when you thought you'd cracked it.

Here's the reframe that helps most: the vast majority of regressions aren't your baby going backward — they're your baby moving forward. They cluster around predictable ages because they're driven by predictable developments: a maturing brain, new physical skills, growing awareness, and big emotional leaps. The sleep disruption is a side effect of progress.

This post is a hub and map. Below you'll find a single chart of every common regression age with its cause, typical duration, and biggest fix — then a short section on each age that links straight to our dedicated, in-depth guide for it. Use the chart to orient yourself, then jump to the full post for wherever your baby is right now.

Two honest caveats before the chart. First, ages are approximate — babies don't read calendars, and a "4-month" regression can show up anywhere in a window around that age. Second, not every baby has every regression, and some sail through several. If your baby's disruption comes with fever, pain, or anything that worries you, that's a question for your pediatrician, not a regression to wait out.

Here's every common regression age at a glance. The one that stands apart is the 4-month regression: it's not really a temporary blip but a permanent maturation of how your baby sleeps — which is why we handle it a little differently below.

Age	Main cause	Typical duration	Biggest fix
4 months	Permanent maturation of sleep into more adult-like cycles	Permanent change — settles over roughly 2-6 weeks as your baby adapts	Support independent settling; don't wait it out — this is the new normal
6 months	Starting solids, teething, rolling, emerging separation anxiety	About 2-4 weeks	Steady routine; rule out teething/feeding discomfort
8-10 months	Separation anxiety plus motor milestones (crawling, pulling up)	About 2-6 weeks (one long, uneven cluster)	Reassure without creating new sleep crutches; daytime skill practice
12 months	Walking, standing, developmental leaps; possible nap changes	About 2-6 weeks	Hold the schedule; don't drop the second nap too soon
15 months	Brain processing new skills, awareness, and emotions	About 2-4 weeks	Consistency; avoid introducing new sleep associations
18 months	Independence and testing limits, language explosion, separation anxiety, molars	About 2-6 weeks (often the longest)	Firm, kind boundaries; keep bedtime predictable
2 years (24 months)	Cognitive, emotional and practical changes colliding — fears, big feelings, transitions	About 2-6 weeks	Consistent limits; address new fears calmly

Notice the shared thread down the "biggest fix" column: consistency, a routine that fits your child's current needs, and not accidentally creating a new habit while you ride out a temporary wobble. That single principle carries you through nearly all of them. The detail — exactly why it's happening and precisely what to do — lives in the dedicated posts below.

The 4-month regression is the most important one to understand because it's not temporary. Around this age your baby's sleep permanently matures into more adult-like cycles with lighter phases they surface from — which is why a baby who used to sleep in long stretches suddenly wakes fully between cycles and needs help getting back down.

Because it's a permanent change rather than a passing phase, the goal isn't to "wait it out" — it's to gently support your baby in learning to resettle under the new normal.

Read the full 4-month sleep regression guide →

Around six months, several things land at once: starting solids, teething, rolling, and the first hints of separation anxiety. It's usually shorter than the others — often a couple of weeks — and much of the fix is ruling out genuine discomfort (a sore gum or an unsettled tummy from new foods) versus a true sleep wobble.

Read the full 6-month sleep regression guide →

This is less a single event and more a long, uneven cluster spanning roughly the 8-to-10-month window. Its two engines are separation anxiety (peaking around this age) and a burst of motor milestones — crawling, pulling to stand, cruising. Babies often practice their new tricks in the crib at 2 a.m. The key is reassuring without building a new crutch you'll have to undo later.

Because it's a cluster, we cover it across three linked guides:

• The 8-month sleep regression →
• The 9-month sleep regression →
• The 10-month sleep regression →

Right around the first birthday, big gross-motor leaps — standing and walking — plus developmental changes disrupt sleep. A common trap here is mistaking the disruption for readiness to drop to one nap; for most babies it's too early. Holding the schedule steady is usually the answer rather than cutting daytime sleep.

Read the full 12-month sleep regression guide →

The 15-month regression is driven by the brain processing new skills, new awareness, and new emotions. It tends to be on the shorter side and responds well to plain consistency — the main risk is quietly introducing a new sleep association (an extra rock, a new feed) while you're tired, and then having to unwind it.

Read the full 15-month sleep regression guide →

Often the toughest of the lot. The 18-month regression stacks several things together: a surge of independence and limit-testing, a language explosion, another wave of separation anxiety, and molars coming through. It can also run a little longer than the others. This is where firm-but-kind boundaries and a rock-steady bedtime routine earn their keep.

Read the full 18-month sleep regression guide →

The 2-year regression is a collision of cognitive, emotional, and practical changes that tend to arrive together: bigger feelings, new fears (of the dark, of being alone), a drive for control, and often looming transitions like potty training or a new sibling. Consistent limits and calmly addressing new fears are the core of getting through it.

Read the full 2-year sleep regression guide →

Whichever age you're facing, the same handful of principles carry you through nearly every regression:

• Reassure without inventing a new crutch. Comfort your baby, but try not to introduce a brand-new habit (a 3 a.m. feed they don't need, hours of rocking) that you'll have to undo once the phase passes.
• Protect the routine and the schedule. Regressions are a reason to hold your bedtime routine steady, not to abandon it. Check your wake windows still fit your baby's age.
• Rule out the non-regression causes. Teething, illness, hunger, and an overtired or undertired schedule all look like regressions. Our guide on telling a regression apart from teething can help.
• Expect it to be temporary — except the 4-month one. Most regressions resolve within a few weeks. The 4-month change is permanent, so it needs supporting rather than waiting out.
• Keep safe sleep constant. New skills like rolling and standing don't change the rules — back to sleep, bare crib. See our AAP safe sleep guidelines.

If a "regression" drags on well beyond the usual window, comes with fever or pain, or just doesn't feel right, treat that as a reason to check in with your pediatrician rather than to keep waiting — and for any emergency, call 911.

For the full picture — safe foundations plus gentle, workable habits through every stage — our online sleep course pulls it all together in one calm, worldwide-friendly plan.