Your 15-Week-Old Baby

This week is all about sleep. At around this age (between three and five months), many babies experience their very first sleep regression. To help make sense of the sudden shift in routine, we turned to experts Amanda DeLuca, pediatric sleep consultant and founder of the parenting app Riley, Dr. Chris Klunk, board-certified neonatologist at Pediatrix Medical Group and Dr. Gabriella Dauer, pediatrician and author of Beyond the Basics: A Pediatrician's Newborn Guide for their advice.

We’ll also touch on how to spot the difference between sleep regressions from teething or illness, the best strategies to survive those extra nighttime wakeups (for both you and baby) and when’s the right time to move your baby from a bassinet to a crib. Here’s to happier sleep for everyone, no matter the (developmentally appropriate) disruption.

🚼 Baby’s Development 

4-Month Sleep Regression

Just as your baby was finally starting to sleep in longer stretches, here comes yet another development: meet the (in)famous four-month sleep regression, ready to shake up your routine (temporarily, thankfully). “The four-month sleep regression can feel brutal,” DeLuca says. But what exactly is a sleep regression, and what makes the four-month mark so special? 

A sleep regression is, unfortunately, exactly what it sounds like: it’s when a baby regresses in their newly learned sleep skills, whether that’s sleeping in longer stretches or through the night, reducing their number of naps or just generally off-setting their routine. And with the four-month regression being the first, it’s important to know the what and the why behind it. 

“A hallmark of this regression is that [baby’s] wakings are frequent and often random, not just once or twice to feed,” DeLuca says. “Timing is a big clue. This regression usually hits between three-and-a-half and five months, so if your baby was sleeping relatively well and then suddenly starts waking up more often around this age, especially every one-and-a-half to two hours, that’s a strong hint.”

And those wake-ups often aren’t the drowsy, sleepy-eyed kind. Your baby may suddenly seem wide awake in the middle of the night, DeLuca says—alert and playful, not just hungry. And naps may shorten too, adding to everyone’s fatigue. Which may leave you asking, “why?”

“The first sleep regression is sometimes blamed on babies’ expanding attention to, and interaction with, the world around them,” Dr. Klunk says. “Newborns don’t have great eyesight, can’t move their heads much and generally have limited ways to appreciate and affect their surroundings. Not so much the case by four months.” Essentially, all the developments you’ve been witnessing over the past 15 weeks—seeing color, tracking objects, recognizing sounds and faces—mean your baby thinks they have better things to do right now than sleep, Dr. Klunk says. 

Keep in mind that sleep regressions can sometimes be confused with other disruptors like illness or teething, which have their own unique symptoms to watch out for. A sick baby can have congestion or fever and a teething baby can have lots of drooling or seek out things to chew on, but DeLuca says that a sleep regression baby who is otherwise healthy won’t have any additional symptoms besides disrupted sleep.

Having all those extra nighttime wakings and shorter naps can be tough, but experts have advice on how to get through it. “Maintaining the nighttime and overnight routine is the BEST way to get through sleep regressions,” Dr. Dauer says. “Gently pat baby’s back, give them a snuggle or two, feed them if it’s time for a feeding and back to the crib.” 

Keep doing what you’ve always done, and don’t give in to baby’s wakefullness, especially in the middle of the night. Extra attention will just result in your baby waking up even more or preferring to fall asleep with you, Dr. Dauer says, potentially regressing on any self-soothing skills they’ve learned.

💗 You, 15 Weeks After Baby

Sleep regressions don’t just impact babies—they can throw the whole family off balance. When your nights are broken into 90-minute chunks, your patience, energy and even decision-making skills can take a hit. Remember what it was like 15 weeks ago during the earliest newborn days? Just like during that phase, taking care of yourself during sleep regressions helps you take better care of your baby. 

DeLuca says to keep sleep signals and routines (both yours and baby’s) as consistent as possible to help yourself get the best quality sleep possible. “Through years of supporting families in their most vulnerable moments, I’ve discovered that consistency becomes your lifeline when everything feels chaotic,” DeLuca says.

Don’t lose your sanity over sleep regressions. If you’re really struggling through the extra nighttime wakeups, try to split nighttime duties with a partner if possible, or nap during the day when your baby naps. Ask for help with meals or household chores so you can conserve your energy for the basics. 

😴 Sleep

🛏️ Total Sleep: 14–16 Hours

At 15 weeks old, babies need about 14 to 16 hours of total sleep in a 24-hour period. That usually includes several naps and longer stretches overnight, but during a sleep regression, it may feel like your baby isn’t getting enough hours. Rest assured (pun intended) that sleep regressions are totally normal and developmentally appropriate, and your baby will go back to getting their regular amount of sleep once the phase is over.

To help maximize your baby’s sleep in spite of a regression, Dr. Dauer says to focus first on their naps, making sure they’re getting extra sleep during the day if needed (especially to make up for lost sleep at night) and aren’t napping too close to bedtime.

❓Weekly How-To: Sleep Space Transitions

While we’re talking about sleep, you may be wondering when your baby should move from their bassinet into a larger crib. The answer depends on the bassinet’s specific guidelines and your baby’s unique size, weight and whether they can pull themselves up.

When it comes to bassinet guidelines, Dr. Dauer says that some bassinets may fit babies up to three months old while others may fit up to six months old—it just depends on height (length) and weight limits. But even if your baby hasn’t yet reached those limits, “as soon as your child is able to sit up, [it’s] absolutely time to move to a crib,” she says.

Whether your baby maxes out the product limits first or reaches the sitting up milestone before then, Dr. Dauer’s advice is to not prolong the transition period. “I personally would make the shift swiftly and early and be consistent with the new environment,” she says. Especially if baby is going from a moving/rocking bassinet (like the SNOO) to a regular stationary crib, a slow or inconsistent transition can make it harder for baby to adjust to their new sleep space.

If you’re worried about your baby feeling insecure in their crib (since it’s so much larger than a typical bassinet), there are a few things you can do to help the transition not be so jarring. Dr. Dauer recommends keeping baby swaddled or in a sleep sack exactly like they were in their bassinet so they can still feel that sense of security. You can also consider a mini crib rather than a full-size crib; mini cribs are closer in size to a bassinet, but with higher weight limits. Your baby may still outgrow a mini crib length-wise within just a year or so, but a convertible mini crib can help solve for that by transitioning into a toddler bed when your little one is ready.

And remember to maintain a safe sleep space—don’t add things like blankets, pillows or stuffies to the crib, since they’re suffocation hazards. 

👀 Looking Ahead 

• 4-month checkup: Your baby’s next well-visit is just around the corner. This appointment usually includes growth measurements, developmental checks and routine vaccines. Want to prepare ahead of time? Here's everything to expect from this checkup.

• Sleep training & dropping a nap: That’s right, we’ll be talking about sleep again in just a couple weeks as your baby gets closer to needing one less nap per day. This is also the point when some parents start looking into sleep training, so we’ll cover that too in Week 17.

🛍️ Panic Order

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