Pre-natal & Newborn course
The Science of Sleep
Babies are growing and developing every single day and sleep is a hugely important part of this development. During sleep, our children take growth spurts and advance their cognitive development in memory, language and motor skill to name a few. I am really passionate about the science behind sleep and I use this science as a basis for my sleep training. What I’m going to do in this video is tell you a bit about the science of baby sleep, and how we can use that knowledge to help instil some good sleep habits which will allow your baby to be the sleeper you want them to be.
2.1 Day/Night Rhythm (The Circadian Rhythm)
A Circadian Rhythm is an internal, natural process that regulates our body in roughly 24-hour cycles. The most well-known circadian rhythm is the wake-sleep cycle which I will discuss in the next section. It’s connected to a ‘master clock’ in our brain which is highly sensitive to light, helping us to differentiate between day and night. Other cues such as temperature, noise and activity can also affect this master clock.
Exposure to light for a child (and adults) sends signals to the body which create alertness to help the child stay awake. As night approaches, the master clock begins producing melatonin, which is a sleep hormone, and it repeats this through the night to help our babies sleep better and longer. This is why it’s important to have our little one’s sleep environment as dark as possible, and make sure they are exposed to natural light in the day.
Jet lag is a great example in adults; remember how groggy you felt if you have suffered with it in the past? Until we get our child’s rhythm right, they aren’t operating at their best which can impact their mood, and ultimately their development.
2.2 Wake-Sleep Cycle
An adult’s wake-sleep cycle will likely be 7-9 hours of sleep and 15-17 hours of wakefulness in a 24-hour period. For children, sleep hours are a larger portion of the day which will reduce as your babies gets older. However, that period of night time sleep should always be around 11-13 hours, with day naps varying depending on age.
Adults and children go into a much deeper sleep in the earlier part of the night. This is due to the production of a sleep hormone called melatonin. When our babies have the correct day/night rhythm in place, they will start to produce melatonin naturally at night time. We can further promote it with the use of a consistent bedtime routine which helps wind them down and gives the body cues that bedtime is approaching.
As the night goes on, melatonin production slows down as your baby’s body prepares for waking. As the melatonin production slows, another hormone called cortisol starts being produced. This leads to lighter sleep in the latter part of the night and can often result in multiple night wakings or early wakings. The importance of the child’s body clock and regulating the hormone for sleep (melatonin) and the hormone we produce when awake (cortisol), is significant for their ability to sleep longer and better at night.
When I talk to clients about over-tiredness being the devil, it’s because when a child is over-tired they will be slightly grumpier, fight sleep and end up producing more cortisol. Therefore, the right amount of daytime naps and an appropriate bedtime will help your child in not becoming over-tired. Not only do they become more difficult to settle at bedtime, the build-up of cortisol in their body won’t disappear immediately, leaving a more-than-normal amount overnight which can then lead to wake-ups in the night and/or lighter (less quality and less restorative) sleep.
I am going to go into these a lot more throughout this course, but the key areas and steps you can take to positively impact the wake-sleep cycle are:
- Seek out sun for your little one as much as possible. Exposure to that daylight helps reinforce the circadian cue.
- Be consistent with your baby’s sleeping and waking periods. Varying bedtime or morning wake up time can confuse the body clock, leading to unsettled bedtimes and early wakings.
- Create a consistent bedtime routine, enabling your baby to understand the cues for night time. This will help their body prepare for sleeping at night.
- Regular exercise and stimulation for your child will not only help their physical and cognitive development, it will help support their internal body clock and assist them to fall asleep easier at night.
- Limit artificial light before bed. This can include dimming the lights or avoiding electronic devices, including TV, at least one hour before bed.
Melatonin
This hormone is naturally created in the human brain’s pineal gland. It’s production is facilitated by darkness and so it helps regulate the circadian rhythm and synchronise wake-sleep cycles in humans. Babies aren’t born with melatonin but they do start producing it naturally very quickly which will help them differentiate between daytime and night time sleep.
Very young babies don’t produce melatonin but once they reached a few months of age, our children will have started to produce it naturally. As circadian rhythms are established their brains create this at regular times over a 24-hour period.
Sleep environment and regular routine is key in supporting their bodies to do this.
Cortisol
Think of this as the ‘wake-up’ hormone. The brain controls production of this hormone at key points in the 24-hour cycle when we need to naturally rouse and wake up. Without this we wouldn’t be able to get out of bed in the morning!
Over-tiredness is the enemy of good quality sleep. When a child is overtired, either from inadequate amounts of sleep (day or night) or a late bedtime they can produce cortisol to give them a ‘second wind’.
Cortisol can build up in the body and is hard for children to work through their system. So, when they most need sleep, the cortisol makes it harder for them to unwind and fall asleep. This can lead to them fighting sleep, multiple wake-ups once they do fall asleep and periods of lighter sleep instead of the deep restorative sleep they need.
If your child has been waking up very early for some time it can take a while for them to adjust to waking up later as their body has been used to creating cortisol early in the morning. Once their sleep is on track, later wake-ups can often be one of the last improvements you see, but stick to the routine and it will come with time.
2.3 The Sleep Cycle
Where the wake-sleep cycle focuses on day and night, The Sleep Cycle is what we do during those periods of sleeping. Understanding how sleep works in children can help us to work out suitable methods for establishing healthy sleep habits. There are 2 types of sleep: REM Sleep (light sleep) and Non-REM Sleep (deep sleep).
Light sleep and deep sleep alternate in approximately 45 minute cycles for young children (approximately 90 minutes in adults) which is shown in the diagram below. In between sleep cycles, all humans arouse/wake, albeit briefly so most people don’t remember them at all. These ‘wakes’ during the night are completely normal, but it’s the inability to return to sleep after these wakes which can cause sleep problems.
If your baby has been using an external sleep associations (I will go into this in much more detail throughout the course but examples are feeding for comfort, a dummy, sleeping in parent’s bed) to help them get into their first sleep cycle, or back to sleep from a wake during the night, they will continue to seek that external comfort again and again.
This course will show you how to help your baby get back to sleep from those wakes without sleep associations, teaching them how to self-comfort which is the key part of independent sleep.
