Baby Sleep: Naps Decoded

January 12, 2022

Updates, Aug 1, 2023 – Few infant sleep issues are as frustrating as naps. We break down baby’s awake and sleep cycles week by week here in Baby Sleep: Naps Decoded to help you understand when baby is ready for a rest. This allows for more sleep and fewer meltdowns.

Baby Sleep: Naps Decoded – Understanding Sleep Cycles

Newborns and infants sleep differently than adults. There are several reasons for this and once we understand them we can work with their natural rhythms to help them sleep longer and without fuss.

1. They’re tiny! – Newborns have small stomachs so they need to eat frequently. Their tummies can only hold small amounts of breast milk or formula and this nutrition gets digested quickly. As a result, they wake up frequently to feed, typically every 2 to 3 hours.
2. Hunger, need for comfort or growth spurts – Babies usually wake up if they’re hungry, have a wet or dirty diaper, or are experiencing discomfort due to issues like teething or gas. Additionally periods of growth mean their bodies and brains are developing rapidly, leading to more frequent waking during the night.
3. Immature sleep patterns: Newborns have an immature sleep-wake cycle, and it takes time for their circadian and ultradian rhythms to develop. This means that their sleep is not yet regulated by day and night patterns, and they have shorter sleep cycles compared to adults.
4. Melatonin isn’t Present Yet!: Just like #3 above, your newborn is still developing. Newborns receive melatonin, widely known as the sleep hormone from the placenta but don’t start developing their own until they’re about 8-9 weeks old.

Baby Sleep: Naps Decoded – Circadian Rhythm

Circadian rhythm is nature’s mechanism to regulate our awake and sleep times over the course of 24 hours. Within this daily cycle are ultradian rhythms, which are 30- 90 minute wakeful/sleepy patterns.  This 30-90 minute pattern repeats over the course of 24 hours. There are a lot books written about baby sleep and getting baby on a schedule and they’re all based on this cycle. This can be confusing , so let’s break down how this pattern works:

Ultradian Rhythm

Circadian rhythm and sleep cycles are controlled by serotonin and melatonin.  

• Serotonin produces alertness during the day and is triggered by daylight.

• Melatonin produces sleepiness during the night and is triggered by darkness. 

If we visualize the cycle using a 6 month old for example, baby is wakeful at the top of the curve (45 minutes after waking up) and then sleepy at the bottom of the cycle (90 minutes after waking). So, about 5-10 minutes before the 90 minute mark is when they should be in their crib, prepared to sleep.

Like this:

Here’s the tricky part though! In full-term newborns, melatonin isn’t fully produced until weeks 9-12 so they don’t start out on a 90 minute cycle, they build up to it. Getting baby down to rest before their internal “clock dings” at the end of their time awake. This is key to ensuring baby doesn’t enter into another wakeful period. This is one thing that makes them fussy and can lead to being overtired.

Remember: Baby doesn’t start to go down for a nap at the end of their 30, 45, 60 or 90 minutes awake. They should already be in their crib at the 30, 45, 60 or 90 minute mark.

Here’s a breakdown of newborns’ basic awake and sleep times:

Baby Sleep: Naps Decoded

• Weeks 0-2: Baby is awake for a maximum of 30 minutes. Most of this time is spent feeding and baby will appear sleepy even during wakeful periods, often falling back asleep with no help at all.

• Weeks 3-8: Baby is awake for a maximum of 45 minutes. You’ll notice baby is more wakeful around week 8; s/he won’t just go right back to sleep like s/he used to and may need your help to stay asleep. Baby wearing, white noise, giving a pacifier to help sleep are all fine to do because at this age baby needs your help to get and stay sleep.

• Weeks 8-12: Baby is working on and eventually awake for 60 minutes. Napping will become longer during these weeks as well but it’s perfectly fine and even recommended to help baby with napping when s/he pops up after 10-15 minutes or so by giving a pacifier, using white noise etc.  You’re not creating bad habits, baby simply needs a little help to not fully awaken because the systems that make seratonin and melatonin are not quite mature yet.

• Weeks 12 – 18: Baby is working on and eventually is awake for 90 minutes. Baby is even more alert and still may need help getting and staying asleep. If your goal is to have baby eventually sleep through the night independently, try not to pick baby up if she wakes before a 90 minute nap is done. Instead, stay near to comfort with patting on the back or giving pacifier while baby is still asleep, but exhibiting signs of waking up like twitching or moving her head back and forth.

• Weeks 18 -24:  Baby is awake for 90+ minutes and consolidates naps now. There may be fewer naps that vary in length but a nap of at least 90 minutes will provide adequate rest. S/he will usually be awake for some increment of 90 minutes (11⁄2 hours, 3 hours, 4 1⁄2 hours).  

What’s Next?

If your goal is to have baby sleep long stretches overnight without feeding, the 4 month well check is a great time to start talking with your pediatrician. These longer stretches of sleep are really just one big nap consolidation! They can help you to know whether baby is developmentally ready to sleep for at least 6 hours uninterrupted.

If you’re ready for your baby to sleep through the night, start with an appropriate routine. While the cry-it-out method gets a lot of press, sleeping through the night can be a gradual process where baby’s body adjusts to less milk overnight, making sleep a natural next step to waking from hunger. This is detailed here.

Baby Sleep: Naps Decoded – Important Notes

Sometimes even though we’re doing everything right, babies cry. A LOT.

They might cry because of colic, could be overstimulation, reflux or any other reason only known to your baby. Even if you follow this blog or any sleep advice exactly as it’s written, babies are not robots.  You’re doing a great job, but if you’re concerned about baby’s crying or health, please contact your pediatrician. 

These guidelines are for full-term babies without any health issues. Preemies and twins are often born early and therefore smaller than full-term newborns. Many singletons also arrive sooner than expected or bring health issues so these guidelines might need to be modified. Some babies need to be woken up to feed to gain weight for example. You can never go wrong with patience, following doctors’ orders and responding to your baby’s needs.