Sleep Cycles Explained

Let’s learn about sleep cycles. Why? It’s important to know how sleep works, in order to understand what we can do to help our kids sleep.

Newborn Sleep

Sleep for a newborn (0-4 months) is fundamentally different than for an older baby, toddler, or adult. Newborn sleep cycles usually last 40-50 minutes and consist of about 50% Active Sleep (REM Sleep) and 50% Quiet Sleep (Deep Sleep). Unlike sleep for older babies, they start their sleep cycle in REM sleep, and then move on to deep sleep.

They spend about 20-25 minutes in Active Sleep, 20-25 minutes in Quiet Sleep, and then they might wake up – either for good, or to start a new sleep cycle. Most newborns still need help connecting sleep cycles.

Keep in mind that your newborn is very easy to wake up during active sleep, and, as the word suggests, the baby might move around, wiggle, grunt, even cry or briefly open his eyes. Totally normal!

Baby and toddler sleep

After the initial newborn phase, sleep for babies and toddlers look much alike adult sleep. As their sleep cycles mature, and other developmental progress happens, your little one might hit the much dreaded 4-months sleep regressions. But no worries, I am working on a new blog post on regressions as well!

At that age is also when we see sleep to get more consolidated. The sleep cycles become longer, and while some might not be able to connect the cycles by themselves quite yet, their sleep tends to get more predictable.

Sleep stages

Every person goes through 4 sleep stages in every sleep cycle, and through multiple cycles every night. Each cycle varies in length, starting at around 50 minutes as babies and slowly increasing to about 90 minutes by the end of toddlerhood, and into adulthood. Now, what are those stages, and why are they important?

Non-Rem Sleep (NREM Sleep)

For babies past the newborn stage, toddler, and adults, sleep starts with NREM Sleep. It consists of 3 separate stages:

  • Stage 1 or N1:
    In this phase your baby is falling asleep. The brain activity is starting to slow down and the body is starting to relax. Babies can wake up very easily in this phase.
  • Stage 2 or N2
    This is a light sleep phase in which the muscles are relaxed, the body temperature drops, and breathing as well as heart rate slow down.
  • Stage 3 or N3
    This is a deep sleep phase. It is harder to wake your little one up from this phase, as the body is completely relaxed and the brain is going through slow-wave sleep. This phase is very important for restorative sleep, it helps the body recover and grow. It is believed that this phase helps boost the immune system and aids creativity and memory.

Rapid Eye Movement Sleep (REM Sleep)

During this phase the brain activity picks up again, but the muscles in arms and legs are temporarily paralyzed. Eyes are moving around quickly (hence the name), and vivid dreams occur. This phase is important for learning and memory. And we all know there is a lot of learning to do in the first few years!

How it all plays together:

Sleep cycles change throughout the night

The deep sleep phase is longest at the beginning of the night, and getting shorter after the first half of the night, while the REM sleep starts off shorter and extending toward the morning. Your light sleep phase is also getting longer toward the morning.

What that means for your child’s sleep

Knowing all that helps us to understand how we can improve your kid’s sleep.

A common phenomenon we see is baby sleeping well for the first half of the night, but then frequently waking toward the morning. Looking at the fact, that their deep sleep phase is longer during that time, but shortens as the night goes on, can be one explanation of it. Read my blog post about early morning wakings to find out how to get your child to sleep longer in the mornings.

Another one of the most common issues I hear form parents is that their kid is up every 1-2 hours at night, needing to be rocked or fed back to sleep. Why do they wake up so often? They are done with one sleep cycle and need help connecting to the next.

It all makes sense now, right?

How can you help your little one connect sleep cycles, and ultimately sleep through the night?

Some babies are naturally able to connect sleep cycles. But, since you are on my website, I’m guessing your child isn’t one of them. The best way to help your little one connect sleep cycles, is to teach them how to fall asleep independently. When they briefly wake up between sleep cycles, they need the same conditions as when they fell asleep. If you rocked, fed, sang them to sleep at bedtime, they will most likely need it for middle of the night wakings as well.

To teach them how to fall asleep independently, you will have to sleep train your baby. I’m not saying every child needs to be sleep trained, but if sleep just isn’t working out for you, this is the way to go. There are several different sleep training techniques (watch out for future blog posts), that range from very gentle to not so gentle. Please know that sleep training DOES NOT mean you are leaving your child to cry it out. Need help getting started? Schedule your free call with me now and talk about how I can help your family get they rest you need to thrive.


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