She had been sleeping seven solid hours for about a month. You stopped expecting it to fall apart. You started to assume this was just who she was now: a good sleeper.
Then around month eight, you walked in to find her standing up in the cot at 1am, gripping the bar, screaming the kind of scream that you can hear from the bottom of the garden.
Welcome to the 8 month regression. Also known as the 9 month regression, or the 10 month regression, depending on which baby you ended up with. Most kids hit it somewhere between 7 and 10 months, and it's nearly always the same cocktail of three things hitting at once.
What's actually changed in her
Around this age, three huge developmental shifts arrive within weeks of each other.
1. New physical skills (and she has to practice them)
Pulling up, crawling, cruising along furniture, eventually first steps. Her brain has just acquired a brand new toolkit, and it cannot stop running drills, including at 3am. She will literally wake up and start standing in the cot because her body has not finished processing the new skill from yesterday.
2. Object permanence kicks in
Around 7 to 9 months, babies figure out that when you leave the room, you continue to exist. This sounds like good news. It's not. The flip side of "she still exists when I can't see her" is "she is gone right now and I don't know when she's coming back." Hello, separation anxiety.
This is why the bedtime drop that used to be casual is suddenly a full crisis. You walk out and she logs it as a loss.
3. Real teeth start coming
The big molars don't show up yet, but the front teeth are usually breaking through somewhere in this window, and the gum pressure is at its worst at night when there's nothing else for her to focus on.
Three new things, all at once. It's not your imagination.
What actually helps
Unlike the 4 month regression, this one has more useful levers because she's old enough to learn a few real skills now.
1. Drill the new physical skill during the day
If she's standing up in the cot at midnight, spend ten focused minutes after lunch practicing how to sit back down from standing. Hold her hands. Walk her through it. Most cot-standing wakeups end faster once she can physically get back down on her own.
2. Lengthen the goodbye, don't shorten it
The instinct is to sneak out. Don't. Add a tiny, predictable goodbye ritual that you do every single time you leave her: "Mama is right outside. I'll come back. I always come back." Same words, same order. She's not understanding the meaning yet, she's locking onto the pattern.
3. Watch the wake windows again
By 8 months she can stay awake longer (2.5 to 3.5 hours between sleeps), but overtired is still the single biggest predictor of bad nights. If she dropped a nap recently and is going down at her usual bedtime, she's probably exhausted by 6:30pm. Move bedtime earlier for two weeks.
4. Sleep training, if you want to
If you didn't sleep train and you're now exhausted, this is a reasonable age to start. A baby of 7 months plus, who is healthy and gaining weight, can generally learn to fall asleep without being rocked or fed within about two weeks. Cry-it-out, gradual retreat, pick-up-put-down, all of these methods have decent evidence. Pick the one you can stick to. Consistency beats method.
If you don't want to sleep train, that's also fine. The regression ends naturally, just slower.
5. Don't accidentally create a midnight party
Around month 8, lots of babies start a 1am wake that turns into a 90-minute hangout because the parents are too tired to fight it. They get fed, they play in the cot, they finally fall back asleep at 3am. Within two weeks this becomes a habit her body learns to expect.
When she wakes at 1am, keep the room dark, keep contact minimal, no playing, no full feeds unless she genuinely hasn't eaten in 4+ hours. Boring middle-of-the-night responses end midnight parties faster than anything else.
When this will end
Most 8 month regressions resolve within two to four weeks if you stay consistent. The trick is that this is the worst regression to ride out without changing anything, because separation anxiety actually gets worse if she learns that screaming summons you for entertainment.
So this is the one where being a little more deliberate pays off. Not harsh. Just consistent.
What you need to hear at 2am tonight
You are not back at square one. The eight months of sleep work you already did didn't vanish. Her brain has just temporarily reorganised itself around three new skills she didn't have last week.
The parent at 2am, walking to the cot in the dark, feeling slightly furious about all of it, is the parent who is doing it right. The frustration is allowed. The exhaustion is allowed. The brief two-second thought of "what if I just left and went to sleep in the car" is allowed (and universal).
You're not failing. She's not regressing as a person. Her brain is upgrading, and that upgrade comes with a fortnight of awful nights.
By month nine or ten, she'll be sleeping again. By her first birthday you'll have forgotten which week this even was. That's the part nobody tells you. The bad weeks don't get a chapter in the photo album. Only the good ones do. So you keep going.
Even now. Especially now.