Learning about sleep science has been very interesting for me and has helped me to better understand how to help my entire family with getting better sleep. In this post, I will do a brief introduction to some of the basics of sleep science.
Why do we sleep?
We spend a big chunk of our life sleeping, it’s really kind of crazy if you think about it. We can’t survive without sleeping. There’s a lot that happens within our bodies when we sleep and research shows that a consistent lack of sleep has been linked to many health issues. While we sleep, our brain is pretty active. Sleep really lets our bodies and brains rest and recharge.
Sleep Cycles
Sleep may seem simple, but there’s a lot that goes into it. Our sleep is made up of cycles, for adults each of these sleep cycles are somewhere around 1.5-2 hours. For our little ones, once they are about four months old their sleep cycles are about 45 minutes long. Usually around age 5 is when the sleep cycles lengthen to match adults.
Stages of Sleep
Our sleep cycles are made up of different stages. Newborns only have two stages of sleep – rapid eye movement (REM) and non rapid eye movement (NREM). REM sleep is considered to be active sleep, it’s when our eyes are moving under our eyelids and it is the stage that is said to be when we dream. For adults, REM sleep is generally the last stage of a sleep cycle, but newborns can go right into REM sleep.
Around 3 months of age, babies start experiencing all four stages of sleep that we experience as adults. The first three stages are all NREM sleep, and the fourth is REM sleep. Some sources report that there are four stages of NREM sleep, with two of them being deep sleep. They are similar so often these two stages are combined.
The first stage of NREM sleep is actually the transition of going from being awake to being asleep. It’s when our eyes start to close and our body movements and brain waves begin to slow. When you watch your baby fall asleep, you can see this happen. When their eyes start closing, they are in the first stage of sleep even though they aren’t entirely asleep.
The second stage of NREM sleep is light sleep, and it is where we spend a lot of our time while we are sleeping. Our bodies and brain waves have slowed down even more.
The third stage of NREM sleep is deep sleep. Our bodies and brain waves are at their slowest and this is the stage of sleep where it is hard to wake someone up from. This is also what would be the fourth stage of NREM sleep depending on what source you are looking at.
The final stage of our sleep is REM sleep. During this stage, our eyes are moving rapidly, hence the name, and our brain activity is more similar to when we are awake. Something interesting about this stage is that the muscles in your arms and legs are temporarily paralyzed during REM sleep, this would help keep you from acting out dreams. As we age, research shows that we spend less time in REM sleep.
Circadian Rhythms
Our circadian rhythms play a huge role in our sleep patterns. They are part of your body’s internal clock and help coordinate the timing of different bodily processes, including sleep. Circadian rhythms are why we get sleepy at night and they are linked to melatonin production. Melatonin is a hormone our bodies produce when it is dark
Just as melatonin is sensitive to light, so are our circadian rhythms. This is why exposure to light during awake times and dimming the lights and turning off screens as bedtime approaches is helpful for our sleep patterns.
When babies are born, their circadian rhythms are weak and they develop as they grow. This is why newborns’ days and nights can get mixed up and why sleep training not only isn’t recommended for newborns but it actually isn’t even possible. Circadian Rhythms become mature around the time babies start producing melatonin, a hormone that’s important for regulating sleep.
More on Melatonin
Babies generally start producing melatonin when they are about 3 months old. Melatonin is also known as ‘the sleepy hormone’ as it helps prepare our bodies for sleep. Our levels of melatonin are naturally highest at night and then are lower in the morning. Exposure to light at night can impact your body’s melatonin production. This is why I, along with many others, encourage dimming the lights and turning off any screens at least an hour before bed.
Our bodies are really amazing when you start looking into how everything works and the basics of sleep science!
This is really just the basic information about sleep science, so if you want to read more about the science of sleep I’ve included a list of sources below, so feel free to check those out! If you have any questions about your child’s sleep, you can schedule a free discovery call to discuss options of how we can support you.
Sources
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6175794/
https://www.sleepfoundation.org/how-sleep-works/why-do-we-need-sleep
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep
