4-Month Sleep Regression: Why Does it Occur & What’s the Solution?

Those first few months with my newborn twins were probably one of the roughest times of my life. They were really small, and there were two of them, so we were on a constant cycle of feeding, burping, diapering, napping. Neither my husband nor I got much sleep in those first few months, but then somewhere around the 3-month mark, they started sleeping for longer stretches in the night and then, just like that, we were human again.

Unfortunately, that didn’t last! Just a week or two after they’d given up their 3 a.m. feedings, they started waking up at 2 a.m.. Then again at 2:30. Then at 3. And every half hour until morning time. It was hell! I’d run in there, pop the pacifier back in one of my twins’ mouths, and then just as I started to nod off again, the other guy would wake up crying, and I’d go give him his pacifier back too.

I couldn’t figure out what had happened to disrupt our newly established nighttime peace. Why had their sleep regressed? Well, as it turned out, around the 4-month mark, it’s very common for babies to start waking up more regularly in the night. And it’s not actually regression, as much as a developmental shift. I talked to experts to find out what’s happening to your baby at 4-months old, and what you can do to help everyone get a good night’s sleep again.

Why does 4-month sleep regression occur?

Good news, bad news: Your baby is starting to become more social and aware, which also means that he wants more of Mommy or Daddy. “So now, when he wakes up in the middle of the night, he wants you to come in, he wants to see you, especially if you were there when he fell asleep,” explains Deena Blanchard, MD, a pediatrician based in New York City. “If you go in when he cries, then he learns that this is the way to get you to come, so it becomes a repeated behavior, night after night.” Basically, he’s realizing that his cries summon Mommy, so he keeps doing it.

What’s with the constant wakings though? Well, around this age, their sleep cycles are regulating, each of which lasts about 60 to 90 minutes. “We all have sleep cycles that we move through during the night, and our brains wake up a bit as we go from one cycle to the next,” says Natalie Willes, certified infant sleep consultant at BabySleepTrainer.com. “As adults, we are accustomed to just going back to sleep, and don’t even remember waking, but for babies, this is new, so they could be waking up many times in a night.” While some babies can get through several sleep cycles without stirring, some have more frequent disruptions in their sleep.

And when they wake up, they tend to need whatever it was that put them to sleep in the first place. So if Mommy was snuggling her, she needs Mommy snuggles to settle back down. If she had a pacifier in her mouth, she needs that pacifier back. If she was nursing, she needs Mommy’s breast. While it’s great that she’s moving forward in her development, it can be exhausting for new parents.

So, what can you do about 4-month sleep regression?

Well, it’s tricky. This tends to be the time that a lot of parents decide to sleep train. “Your baby won’t be able to fall back asleep unless he has what he fell asleep with originally, whether it’s you, his swaddle, or a pacifier,” explains Willes. “Ideally, you want him to learn how to soothe himself back to sleep without any of those aids, but in order to do that, there needs to be some sleep training involved.” There are several ways to do it, and yes, most do involve some amount of tears, but in the end, your baby will have developed healthy, lifelong sleep habits that allow her to fall asleep, and stay asleep. If this is the road you want to take, discuss methods with your pediatrician and find out if she thinks your baby is ready. Some babies still need their middle-of-the-night feedings at this age, so sleep training (if you want to do it) will have to wait until later.

If you decide you don’t want to sleep train, Dr. Blanchard recommends having very consistent sleeptime rituals. “The message is that, at night, we sleep,” she says. “There needs to be a regular, quiet-down routine at bedtime. When you go in to feed her in the night, you don’t talk to her, don’t engage. It helps develop those cues to your child that this is sleeptime.”

Whatever you decide though, you must be consistent with your decisions. “I don’t have a strong opinion on whether or not parents should sleep train,” adds Dr. Blanchard. “You have to do whatever feels right to you, and there’s research to back up both sides. That being said, you have to stick with your plan. It’s confusing and unfair to let them cry one day and not the next. You have to be all in, whatever you decide.”

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