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What you Need to Know About Infant Sleep Cycles

Understanding your child's sleep cycles can help you understand why your child may be waking every 40 minutes, unable to take a longer nap, and how to help them push through to the next sleep cycle.





Stages of Sleep


From about 4 months old to adulthood, we experience 4 stages of sleep.


STAGE 1: That very initial stage of sleep where you can feel yourself drifting off, but are still somewhat aware and easily awakened.


STAGE 2: The first "true sleep" stage. If you're awakened from this stage, you usually are aware that you were just previously sleeping.


STAGE 3: Slow wave sleep - that deep, regenerative sleep where your body is regenerating and repairing itself, and sparking growth and development.


STAGE 4: Rapid eye movement (REM) cycle sleep. REM sleep is your most active stage, where your brain kicks in and acts as a filing cabinet - filing away and organizing information from the day. This is also the most active stage of sleep where we do most of our dreaming.



Newborn Sleep Cycles


Anyone who's had a newborn can tell you how unpredictable their sleep is. They're awake one minute, sound asleep the next, and they sleep A LOT. Your newborn can sleep up to 17 hours in a 24 hour period.


This is because newborns only experience stages 3 and 4 of sleep. They're either in deep, regenerative sleep or they're in REM (rapid eye movement) cycle sleep. Newborns actually spend 50% of their time in REM sleep vs adults who spend only 20-25% of their time in REM sleep.


This is also why it seems like your newborn can sleep through anything - they only experience the two deepest stages of sleep.



Sleep Beyond 4 months Old


Newborn sleep is very different from the sleep that occurs after your child goes through their 4 month sleep regression (around 3-4 months).


You'll notice around this time your infant spends less time in REM sleep and starts waking more easily, waking more often, and has a harder time falling into that deep sleep. This change is called the 4 month sleep regression - where your infant's sleep cycles mature into more adult-like sleep cycles.


This is completely developmentally normal and every single child goes through this. Some adjust without any issue, while others need a little help from mom or dad to connect their sleep cycles again.

The diagram above shows you what your baby's sleep cycle looks like after their 4 month sleep regression. They don't fall into deep sleep until about 20-30 minutes into their cycle. Then around 30-40 minutes in they start coming out of their heavy sleep and into a lighter sleep stage again.


It's very common for your little one to wake up fully around the 30-45 minute mark at this point, looking for whatever it was that initially got them to sleep to come help them get back to sleep. That could be rocking, feeding, bouncing, shushing, etc.


Some infants make this transition to the next sleep cycle seamlessly by soothing themselves back to sleep, but many will need your help again. This is where you can decide how you want to intervene.






What To Do


After your infant has gone through that 4 month regression, they are now developmentally ready and able to self-soothe. This is when you can begin sleep training if you so desire.



STEP ONE: Transition out of the swaddle


If your little one is still in a swaddle at 16 weeks adjusted age, it's time to transition out, even if they're not rolling, even if they're still startling. Why? Because we want to encourage use of their body to self-soothe, and if they're all swaddled up, they can't get to their hands.


Think about it - you and I move around a ton at night, we get into a comfy sleep position, and we use our body to soothe ourselves back to sleep through movement. Your infant will do the same if you let them.


You can do one arm out for 2 days, the other arm out for 2 days, then Velcro the swaddle around their torso with arms out until you purchase a sleep sack.


I love the open armed sleep sacks that I have listed here.



STEP TWO: Practice the Pause


If your little one is used to you rushing in the moment they awaken, it's time to start giving them a few minutes to try to settle back to sleep on their own before you intervene and do it for them. Start small, give them 5 minutes, and increase that over time.



STEP THREE: Crib naps


Unfortunately, naps that involve movement are not restorative. Think back to the times you've tried to sleep in the car or on an airplane. You wake up feeling like you barely slept, and sometimes you're even more exhausted than when you first fell asleep.


So let's focus on getting to 80% of naps in the crib, and 20% of naps on the go or in a carrier. This gives your baby the opportunity to start connecting their sleep cycles instead of being lulled back to a less restorative sleep through motion.




When Should I Sleep Train?

Whenever YOU are ready. If your child is 16 weeks adjusted age, then they're usually developmentally able and ready to self-soothe. So it's really about when you're ready to get some solid sleep again.




Let's chat!

If you need help sorting through your baby's sleep, set up a free 15-minute consultation with me to discuss my sleep solutions!

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