Sleep: An Overview of Baby's First 18 Months
Being a new parent is overwhelming; trust us, we know. Your questions are all over the place—which is why we’re here, along with our trusted experts, to help.
One of your biggest questions as a new parent is your baby’s sleep patterns. What’s normal? What’s not? When should I be concerned? We gathered all the info on the factors are affecting your baby’s sleep for the first 18 months of her life, and what you can do about it. Sleep does not occur in isolation - physical and cognitive growth are common things that can disrupt sleep. Everything from illness, mastery of physical milestones to nap transition periods and more can impact your little one's sleep.
So let’s start off on the things affecting your child’s sleep, and what you can do about them.
1. Feeding Schedule
Early on, your baby’s sleep schedule will be affected by their feeding schedule. It’s not that your infant is necessarily hungrier at night; it’s that infants’ small stomachs can’t handle much food at each feeding, so they need to feed often, which is why they tend to wake frequently to get the calories they need.
Once your baby passes the 4-month mark, you can start to tweak their feeding schedule. Stick with the same number of feeds, including night feeds, but try to offer more calories during the day to prevent the need to eat more in the night.
2. Growth Spurts
You can expect growth spurts at approximately the following stages during your baby’s first year:
9 months 12 months
Each baby is different, so these are approximate timeframes. But when it comes to sleep disruption, physical growth spurts tend to affect sleep only during your baby’s first 4 months. (In general, growth spurts don’t tend to disrupt sleep in older infants or toddlers; in fact, toddlers typically sleep more during growth spurts.)
So your baby waking during his or her first 4 months at these stages is normal. And the general rule of thumb for a baby over the age of 4 months is to stay consistent with her schedule through the growth spurts—you shouldn’t see any disruption due to growth spurts alone.
3. Cognitive Development (“Leaps”)
There are 10 “leaps” in your baby’s cognitive development during his or her first 2 years. (The Wonder Weeks is a useful tool to help follow these.)
Some babies are extremely sensitive to leaps, while others are not. Typical signs of leaps include disrupted sleep, eating more or less, crying and fussing more, and acting clingy. Some will show signs with each leap; others may only show signs during a few.
For babies who do experience these symptoms, the good news is that these signs typically only affect him during the first part of the leap. Here is when you can expect these cognitive leaps (and remember, these are all approximate and will vary from baby to baby):
4.5-5.5 weeks Leap 1: Changing Sensations 7.5-9.5 weeks Leap 2: Patterns
11.5-12.5 weeks Leap 3: Smooth Transitions 14.5-19.5 weeks Leap 4: Events
22.5-26.5 weeks Leap 5: Relationships
33.5-37.5 weeks Leap 6: Categories
41.5-46.5 weeks Leap 7: Sequences
50.5-54.5 weeks Leap 8: Programs
59.5-64.5 weeks Leap 9: Principles
70.5-76.5 weeks Leap 10: Systems
In our experience, Leaps 5,8,9, and 10 are the hardest on sleep. Your best plan of action is to stay consistent with your child’s sleep schedule and power through.
4. Physical Milestones
First thing’s first: you need to remember that each baby reaches her physical milestones when she’s ready Don’t compare your baby to others (we know, it’s hard!) and don’t worry unless your doctor is concerned.
In general, the biggest physical milestone that affects sleep is crawling. (You can read more about the science behind this here.) Walking can also affect your baby’s sleep. Your child may have refuse naps or take only short naps, have early wakeups, or even some middle-of-the-night wakings.
This is all normal. Again, it is best to stay the course with your child’s sleep schedule. If by this age you’ve used a formal method of sleep training, use whatever method you used originally to power through this time period.
5. Night Weaning
It’s always best to consult your pediatrician about night feeding. As is true for everything else baby-related, each child’s individual situation has its own considerations. Many babies can sleep through the night without a night feeding by 6 months, while some babies may require a night feed through 9 months or longer.
If your baby is over 4 months, here are some signs that he might be ready to night wean:
Your baby does not take a full feeding at his night feeding(s)
Your baby is waking early in the morning (before 5am) and does not return to sleep after you feed him at that time
Your baby wakes up within an hour or two of the last night feeding
Your baby does not return to sleep quickly after a night feeding
You can address night weaning by using a formal sleep training method, or by dropping the number of ounces in her bottle by one ounce every other night until there’s no longer a bottle.
Alternatively, if you’re nursing, you would decrease the amount of time you’re nursing by one minute each night until you’re no longer night nursing.
6. Nap Transitions
You may experience some sleep disruptions around nap transition times. This is normal. Your baby’s sleep needs change as she gets older, and adjusting to one fewer nap per day can be tricky.
Here is when you can expect nap transitions in your child’s first 2 years. Again, these are approximate:
4-5 months 4 naps to 3 naps
5-8 months 3 naps to 2 naps
24 months* 2 naps to 1 nap
*The average age for the 2-to-1 nap transition is 15 months. Some parents may mistake leaps or physical milestone sleep disruption for the need to transition to one nap. We do not recommend rushing the 2-to-1 nap transition.
Signs that it may be time to drop a nap include:
Skipped naps or shortened naps for a week or more
Naps late in the day that push bedtime out too late at night
Bedtime battles or sudden struggle to fall asleep quickly at bedtime
Sudden early wakeups
The best advice we can give during these nap transition times is to compensate with an earlier bedtime as your child transitions. Early bedtimes help prevent your baby from becoming overtired.