What Happens During Sleep?

When I was studying to become to become a Paediatric Sleep Consultant I was blessed to virtually meet  a group of smart, fantastic, supportive, funny women. One of these women has written this excellent, educational article. I feel very lucky to have her permission to share her words with you.

"You know how good it feels to sleep well.  But do you know how amazing sleep really is?  If you could take a peek into what happens during sleep, you might be surprised at the complexity and the beauty of what goes on.  It would also give you a lot of insight into why little ones wake so often.  Let me explain.

You may have heard of REM sleep, which stands for rapid eye movement.  REM sleep is hugely important, but we'll get to that in a moment.  First comes a few stages of non-rapid eye movement, or NREM.  In NREM1, we’re still fairly aware of our surroundings.  This stage serves as the transition from waking to sleep.  Someone awakened from this stage might believe that they weren’t actually asleep.  We pass through this phase fairly quickly.

The second stage, NREM2, makes up most of an adult’s sleep.  It’s still a fairly light stage of sleep, but you’re becoming less aware of anything going on around you.  

During NREM3, heart rate and blood pressure drop; breathing becomes deep and even.  This is the deepest level of sleep, when cell growth and repair occur.  Energy is restored, key hormones are released.  We are least aware of external activity during this stage.  If awakened, you would feel extremely groggy.  Most of our deep sleep occurs during the first third of the night, making it the sleep your body is most likely to protect.

After NREM3, there is a return to stage 2 sleep, and then a period of REM--there it is!--when we are most likely to dream.  This stage is vital for learning and memory consolidation.  Adults experience about 25% of their sleep as REM sleep, but for a newborn this stage can account for as much as 75% of their sleep.  When you think about how fast their brains are growing, this makes a lot of sense.  

While in REM sleep, heart rate and breathing return to close to their waking rates, and the brain is incredibly active.  It is very easy to wake from REM sleep; in fact, adults may wake as many as 9 times throughout the night.  Normally we aren’t aware of these wakings since we return quickly to sleep.  These wakings are protective: they allow us to check on our surroundings, or to shift position so that we don’t become uncomfortable in one place for too long.  For babies, these awakenings also allow them to signal to their parents when they have a need.  If there’s no present need, baby might continue on to another cycle of NREM2, then more deep NREM3, repeating this light--to deep--to light--to dreaming trend through the night.  

Now pause for a moment here, and imagine with me that you’re in an unknown place.  Maybe you’re camping out in the open by yourself.  You’re not sure who else is around or what to expect through the night.  You can’t hold your eyes open for another moment though, and sleep overtakes you.

Would you sleep well?  Probably not.  Any foreign noise would put you on high alert.  A person walking by would startle you.  You would resist allowing your body to go into that deep stage of sleep; the wakings characteristic of REM sleep would give you frequent opportunities to make sure that you were still safe.  Rather than quickly settling back to sleep, you would scan your surroundings to make sure everything was still okay.

What allows us to sleep well when we’re at home and in our own bed?  We know what’s going on around us.  We know that we’re safe.  Because when you think about it, sleeping is an act of trust.  You’re incredibly vulnerable when you’re asleep.  As your environment stays the same night after night, you know that it’s okay to relax and let your guard down.  But if you woke during one of those points of lighter sleep one night and found that a light was mysteriously on in your home, you’d probably be concerned.  Things weren’t as you left them; instead of continuing to sleep you’d go investigate how this light happened to be on.  Note that the light didn’t wake you; it has no power to do that.  You came to a period of lighter sleep, woke, and noticed the light was on.

For your child, this world is a great big unknown.  The way they learn that it’s safe to fall asleep and stay asleep is to know that nothing will change through the night as they reach those frequent periods of REM sleep.  If mom was there as baby fell asleep, waking up during the night to find mom missing would be just as unsettling to baby as finding a light on in the middle of the night would be to you.  This is why consistency is such a big part of sleep for little ones.  If you rely on feeding your baby to sleep each night, each time your baby wakes during the night she’ll need that feeding in order to fall back to sleep again.  How she falls asleep at bedtime is how she needs to return to sleep through the night.  That consistency builds her trust that it’s safe to sleep.  Remember though, that babies spend more time in REM sleep than adults do, and that it’s normal for them to wake often throughout the night.  Committing to helping your baby fall asleep at bedtime means committing to helping your baby return to sleep.  Night after night after night.

The challenge is, no one can keep up with this.  Not without losing your sanity, that is.  We weren’t made to continue to face interrupted sleep without end.  While caring for your newborn at night is part of being a parent, your baby is capable of sleeping for longer stretches by 2-3 months of age, and generally through the night by 6 months of age.  But when your baby’s trust hinges on you being there every time sleep begins (at bedtime) or restarts (through the night), it becomes a black hole that you can never fill.  You simply can’t respond so consistently that your baby decides to stop waking.  

This is why we teach independent sleep.  By providing your baby with a consistent bedtime routine, you build predictability for your little one.  He learns to expect what comes next: sleep.  When we allow our little ones to drift off to sleep on their own, there are no surprises in the middle of the night.  When our daytime interactions have shown baby that we are responsive and they can trust us, that trust translates into a greater ability to fall asleep at night, knowing that we have provided for them.

Will your baby still wake you at night from time to time?  Of course.  It’s developmentally appropriate for babies to continue to wake occasionally throughout the first year.  Learning to roll, crawl, pull to stand, and walk all have a good chance of waking your baby, as he gets to a light stage of sleep and thinks, “I want to practice that new thing that I learned!”  Illness and leaky diapers will often be the cause of your baby summoning you from your bed.  But know that the effort you’ve put into making your actions responsive and predictable to your baby makes a difference.  You’ve taught your baby that surrendering to sleep is a good and pleasant thing, and she can trust you.  

Sweet dreams!" - credit to Sarah Christian, Once Upon A Bedtime.