Your little one's first birthday is usually marked by baby having a taste of cake and smudging some frosting on those rosy cheeks as loved ones look on and snap photos. Chances are, a snag in your little one's sleep schedule wasn't factored into your party plan. But unfortunately, it may wind up being an uninvited guest and make your baby fussy or cranky at her own bash.

If you find that your normally well-rested baby is suddenly having trouble falling or staying asleep again, or is inexplicably up during the wee hours like she was when she was younger, she might be experiencing the 12-month sleep regression.

A sleep regression around the 1-year mark (which can happen as early as 11 months) might feel like déjà vu, since babies can also go through sleep regressions at other ages. In fact, your infant may have experienced a 4-month sleep regression, a 6-month sleep regression and even an 8-month sleep regression, which can occur anytime between 8 and 10 months.

Learn more about why another sleep regression could crop up at this age and stage, and how to get through some sleepless, tear-filled nights.

What is the 12-month sleep regression?

A 12-month sleep regression is a snooze setback in your baby’s regular nighttime schedule — and can happen even after months of solid Zzzs. This night waking may seem to appear out of nowhere, but it’s likely connected to all the new skills your little one is honing during the day.

She’s learning how to maneuver her body in different ways, and she may be talking up a storm. The excitement of her discoveries may leave her feeling fidgety and wanting to practice these new feats at all hours of the night.

The milestones that can be pegged to a 12-month sleep regression include learning to cruise, taking those first steps (or trying to) and uttering first words (or more first words).

Plus, your newly minted toddler is also growing and changing cognitively, which means she may throw a tantrum to protest her bedtime or feel some separation anxiety when she wakes up at night.

How long does the 12-month sleep regression last in babies?

Fortunately for both of you, a 12-month sleep regression should be short-lived and only last about two weeks (give or take). This wrinkle in your baby's nighttime routine should smooth over once the novelty of her new tricks wears off and she realizes there’s no big rush to try them out in the dark.

You might be able to nip a 12-month sleep regression in the bud by leaning hard on the sleep training you've done in the past and sticking closely to your regular tuck-in schedule. Babies and toddlers thrive on sameness and consistency, especially when it comes to their bedtime routines, so keep up the good work and she’ll likely remember what to do.

Causes of the 12-month-old sleep regression

There are a number of changes in your baby’s physical and emotional life that may be causing a 12-month sleep regression, including:

Walking. New toddlers tend to take some wobbly steps around their first birthdays (though many don't walk until a few months or more after they turn 1 and some start toddling along earlier). This super exciting milestone can leave your tot wanting more at night.
Talking. Babbling and early words tend to illicit a shriek of joy from you, and this new trick could inspire your little one to keep it up so she can summon you when the sun goes down.
Night fright. Toddlers who go through a 12-month sleep regression could be experiencing nighttime fears or even nightmares thanks to their ever-expanding imaginations.
Resistance. Your tot isn’t being defiant or acting out yet at 12 months, but a sleep regression can occur when an older baby or young toddler sports some newfound independence and then decides to resist the rituals (yes, bedtime included) that she used to find comfort in.
Changes in daytime sleep patterns. Some babies start to wean themselves off the morning nap around the first birthday, snoozing only in the afternoon. But they may not be ready for that shift yet, making them overtired and messing with their nighttime Zzzs.

Signs your baby is going through the 12-month sleep regression

Here are some signs that could indicate your brand new toddler is dealing with a 12-month sleep regression:

Trouble falling asleep or settling down at bedtime and naptime. Is your 1-year-old or almost-1-year-old no longer going to bed at nighttime or naptime nicely and easily the way she has been? This latest sleep regression could be to blame.
More frequent nighttime wake-ups. If your older baby suddenly starts waking up more overnight again after a good long stretch of sleeping through the night (or close to it), that could be a sign of the 12-month sleep regression.
Fussiness. A baby who’s going through a sleep regression might be short on shut-eye and long on the crankies and even tantrums, so be certain she’s getting the recommended 11 to 14 hours of sleep in a 24-hour period (including naps).
Longer naps. More daytime sleep might mean your sweetie is making up for lost-night-sleep time due to a sleep regression.

Tips for managing the 12-month sleep regression in your baby

Try following these tips when you’re faced with a 12-month sleep regression:

Keep your tot active. Give your 12-month-old plenty of opportunity to walk and talk during the day so she’ll be ready to tuck in at night.
Give your baby lots of attention. You might be able to forestall a tantrum by providing quality one-on-one time with your young toddler. By heaping praise and attention and using some smart distractions, you’ll help her get through some of the frustration she may be feeling.
Patience is key. "This too shall pass," said some smart mother (maybe your own?). Keep in mind that a 12-month sleep regression is temporary, and while a few tears are expected in the short term, your sweetie will soon get back to her regular sleep schedule.

When to call the doctor

A 12-month sleep regression probably doesn’t warrant an immediate call to your pediatrician, but if you’re keeping a list of concerns and questions to bring up at your baby’s next checkup, you can add this one to it.

Remember, as you deal with a sleep regression, keep your own sanity in mind. Unexpected nighttime crying can throw a wrench in your own Zzzs, making it harder to get through the day with a busy young toddler.

Consider playing "pass the baby" with your partner or another helper when the tears begin so you can catch your breath and recharge for the next exciting phase that’s coming down the pike.