As families delve more deeply into what sleep training is and when to start, parents will often ask themselves, “What are baby sleep cycles?” Infant sleep cycles are very similar to adult sleep cycles. However, there are some significant variations which I will cover in more detail below.

what are baby sleep cycles

Photo Credit: Nynne Schrøder

What is a sleep cycle?

Let’s start by defining what a sleep cycle is. Starting at four months of age, babies leave behind their newborn sleep patterns and mature into more adult-like sleep patterns. When a human falls asleep for night sleep, they enter the first of multiple sleep cycles. Infant sleep cycles typically last between 30-60 minutes. And eventually lengthen into 90-110 minute long cycles as they grow older.

One can go into very significant depths when discussing the nitty gritty of sleep cycles. I like to keep the description of sleep cycles more basic. Sleep cycles always start by a sort of “drowsy or twilight” type of sleep. This is generally where you will have a dream that you are tripping on a curb, and then suddenly wake up. Right after having laid down to go to sleep. This drowsy state is followed by the deep sleep state. And finally, each sleep cycle ends in REM (rapid eye movement) sleep.

More About Deep Sleep and REM

During the deepest parts of sleep, some researchers believe the body is unable to feel pain. Deep sleep is where the body repairs itself physically, and where cells are cleaned of their waste.

REM sleep, by contrast, is the emotionally and psychologically restorative part of our sleep cycle. This is where we process what happened during our day. We discard experiences that are not useful or relevant. Like what you had for breakfast 10 days ago, or the radio commercial you heard in traffic. And where more important experiences are turned into memory. Like how to finally play the piano piece properly from start to finish that you have been practicing for 30 minutes each day.

During REM sleep is also when we dream. In fact, while the body is paralyzed during a dream, the brain shows very little difference when in REM sleep than when completely awake and conscious. It is very easy to get woken up during the REM state. And people typically do not feel drowsy or groggy when waking up from a dream. This is because the brain is essentially only very barely asleep.

Upon first falling asleep, we spend just a few moments in the initial drowsy/twilight state. Then we spend the majority of the sleep cycle in deep sleep. Lastly, we finish by spending a few moments in the REM state. As each sleep cycle completes, the brain spends slightly more time in REM sleep, and slightly less time in the deep sleep state. By the time the early morning comes, around 4 am and later, the brain is almost exclusively in REM sleep. This means our bodies are spending very little time in the other states of sleep.

How is a baby sleep cycle different than an adult’s?

Besides having shorter sleep cycles, babies’ brains are doing a lot more during sleep than their parents’ brains. They are also repairing and restoring their bodies during deep sleep, and creating memories during REM sleep like adults. However, they are also only able to grow during deep sleep, and learn during REM sleep! A child is only able to gain weight, muscle mass, etc, during deep sleep. And is only able to “learn” words, sounds, colors, faces, etc, during REM sleep.

I always tell my families that babies not only need more sleep than you do, they also need sleep more than you do! If you find your little one is struggling to get the amount of sleep you feel is necessary, please check out one of Baby Sleep Trainer’s amazing online programs. Healthy sleep for parent and baby is likely much closer than you realize.

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