That's right! In fact, a similar percentage of adults sleep through the night. All human beings go through sleep cycles at night, commonly known as REM cycles. We go from light sleep stages to a deep sleep stage and then start again. When we reset from deep sleep to the next cycle, we slightly wake up. Luckily (most of us) are good sleepers and we are able to get back to the next sleep cycle no problem. Some people get up to go to the bathroom in these cycle changes, I have to drink water to get back to sleep, and some lucky others just grunt or slightly move before getting right on to the next cycle.
For babies (3 months and up) it's a similar thing. They go through cycles (though much shorter than ours) all night. Their very first stages of sleep (20-25 minutes) are the lightest. This is why when you've done everything to put them to sleep in your arms and quietly pray they'll stay sleeping as you place them back in their crib... they wake up!
If a baby doesn't wake up, however, he will then enter a deeper stage of about 20-25 minutes. After this deep sleep stage ends they will indubitably but only slightly wake up as they reset. If baby does not know how to go back to sleep without your rocking/singing/milk then they will call out for help. Babies are resourceful, "I fell asleep to milk last night.. so I need milk to fall asleep. I will call out as long as I need to for that precious sleep serum." Once a baby has what they need to fall back asleep, their little eyes will shut and they will go into another REM cycle. Some REM cycles are deeper than others, some are longer than others. This is why some babies will wake up every hour or so after going down, and others every 90 minutes to two hours.
The unfortunate part is when their "sleep serum" is indeed our help. If you do the math, that accounts for multiple wake ups at night, which is NOT healthy for us. It is definitely not healthy for baby! If a baby (not a newborn) is waking up multiple times at night, when sleep is most restorative, they are not benefiting from night sleep's most important gifts: muscle repair, brain tissue growth, etc... Similarly, adults need night sleep to function! Our circadian rhythms rely on our night sleep for our physical and mental health.
So how can we use science to help us all sleep? The key to a baby's good night sleep is to teach them how to go back to sleep by themselves. This way when they need to transition from deep sleep to the next cycle they won't need to call out for you to help them get back to sleep. They can slightly wake up, make a little noise (even a loud cry), reposition themselves, and go back to sleep by themselves. Once a baby is able to do this, then that's when proud parents can (falsely) boast, "my child sleeps through the night!"
If you need help to teach your baby how to sleep, there are numerous books and online resources! It can, however, be overwhelming how much information is out there. If you would like a personalized sleep plan or consult which takes into account your parenting philosophies, your child's temperament, and your family habits, please reach out to me at www.tiniestdreamers.com or www.facebook.com/tiniestdreamers. I focus on gentle methods with limited crying, but also offer coaching and support with "cry it out" methods if that is your preference.
Here to help you get your tiny one dreaming,
Andrea De La Torre, Certified Baby Sleep Consultant, advocate of good sleep