The Four Month Sleep Regression - What Is It?

The 4 month sleep regression: what is it and why does it seem so scary? If you’ve read anything online about baby sleep, you’ve probably read about this! Maybe your newborn baby went straight to sleep and slept well all night, and then… she turned 4 months old.  Now your baby is fussing at bedtime, waking frequently in the night, and you are confused.  What happened?? A huge change has occurred in your baby’s brain. The 4 month sleep “regression” is actually a PROgression.  That’s right – your baby is developing right as she should. 

When your baby was in the womb, he lived in total darkness. When he was born, living in the bright world was brand new.  You might have noticed that he could sleep in a sunny, noisy room.  This occurs for several reasons, but let’s explore one of them.  At around 4 months old, babies begin to operate like all humans do – in sleep and wake cycles determined by our circadian rhythm.  The circadian rhythm is our bodies’ and brain’s response to the sun.  When it’s light out, we are (generally) awake.  When it’s dark outside, we have a higher drive to sleep.  Through our eyes, our brain receives signals that it is daytime or nighttime, and it secretes hormones accordingly.  One hormone, melatonin, is particularly important for helping our bodies relax and fall asleep at night!

As a newborn, your baby had not yet developed a circadian rhythm.  Now, at 4 months, she has!  Her brain is functioning in sleep and wake cycles much like it will for the rest of her life.  Of course, she needs many more hours of sleep in a day than an older child or adult needs.  But, all of the structures are in place for her to learn that daytime is for being awake, and nighttime is for sleeping.  How cool!

Everyone goes through cycles of deeper and lighter sleep throughout the night.  Babies’ sleep cycles are about 45 minutes, while adults take longer to cycle through all the phases of sleep – about 90-110 minutes.  When we come to a lighter stage of sleep, we (usually unconsciously) look around and check our environment.  If it is the same as we remember from when we fell asleep, we quickly fall back into a deeper sleep.  It’s likely that you rarely, if ever, remember doing this in the morning.  As an adult, it’s such a routine habit.  However, for a baby who is around 4 months old, this is something new!

Perhaps your baby is falling asleep being rocked or fed.  You put her down in her crib asleep and close the door.  About 45 minutes later, you hear her crying.  Why?  She completed one sleep cycle, came into her lightest stage of sleep, woke up and saw that her environment changed, and started to cry!  She remembers falling asleep in your arms and now she is in her bed.  It’s kind of like if you or I were to fall asleep on the couch, and wake up in our bed.  Neither is a bad place to sleep!  But, you or I would certainly be confused if that happened!

So, what do you do now?  It’s great to learn the science behind a baby’s development, but how do you help your baby ACTUALLY fall asleep and stay asleep at night? One of the most important skills for your baby to learn is how to fall asleep on his own.  This skill can be learned in a variety of ways, but it is essential for healthy sleep habits.  There are some babies that can absolutely fall asleep being rocked or fed and sleep all night.  However, they are in the minority.  If your baby is one of these babies, great!  There is no need to change anything.  If, like most babies, your baby has trouble connecting her sleep cycles, there are many tools that can help.  Even in the newborn stage, you can help your baby learn this important skill.  For newborns, this is always taught gently and with a lot of support from mom, dad, or another caregiver.  Once your baby is 4 months old, the techniques change a little, but your baby will still receive a lot of support and comfort from the person he loves most – you!

Come back tomorrow for Part 2 - The Four Month Sleep Regression – Tools in Your Baby Sleep Toolbox!

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