Written by Kelly West (B. Psyc Science)
Behaviour and Development Specialist
This is quite an interesting topic as it has so many facets and differences with each individual child and families approaches to sleep and bedtime routines. There are also cultural differences from around the world that can play a role in the requirements and perceptions and routines of sleep. All of these factors come into play when we and our children sleep and there are mountains of information on sleep so this topic will be completed in a series of installments. This first installment will explore:
1. What is sleep?
2. Sleep Cycles and how they impact on our children’s sleep/wake patterns
3. Homeostatic sleep pressure
Sleep, what is it exactly?
Sleep is that magical time of an evening when we feel our eyelids getting heavier and we curl up in our beds and drift into unconsciousness for 7-9 hours (we hope!). Sleep is a very important part of our lives, rightly so as we spend a third of our lives doing it!
A study referred to by the National Institute for Neurological Disorders and Stroke suggest that sleep plays a “housekeeping role in that it removes toxins in your brain that build up while we are awake”. For young babies and infants, sleep is a period of the day where most growth, repair and development of many tissues, organs and internal systems is focused on. For older children and teenagers, sleep ensures learning is consolidated and provides a sounder learning experience during schooling. For adults, sleep consolidates our day, processes our experiences and refuels our bodies to continue the next day.
Explored in a study found in Sleep Medicine Reviews online journal, the consequences of insufficient amounts and poor sleep quality had possible impacts on children’s emotional regulation, irritability and negative impacts on how children interact socially.
Interestingly, having too much sleep also has negative effects on children’s learning and behaviour as found in a study in the Journal of Clinical Child and Adolescent Psychology. So finding the right balance of just enough sleep is tricky. So what can we do?
We can look at the Australian national recommendations for child and adolescent sleep to find what window of sleep best suits our child. The National sleep foundations recommendations for a 24 hour period (includes naps) are:
• Newborns (0-3 months) between 14-18 hours
• Infants (4-18 months) between 12-15 hours
• Toddlers (18 months – 3 years) between 11-14 hours
• Preschoolers (3-5 years) between 10-13 hours
These times are recommendations not rules so use them as a guide to understand how much sleep we should be promoting for our children each day as they grow. The Rule of thumb as stated by Pediatric sleep researcher A. Sadeh is that “if your child sleeps for less time but shows no signs of tiredness or irritability or sleep-related dysfunction than they are getting enough sleep”. Each individual child’s sleep needs are unique and ever changing (just to make things more tricky for us!). Therefore the best thing we can do is to help them fall somewhere in these ranges and check them for the signs of insufficient advised by Sadeh above.
Sleep Cycles
If our child needs loads of sleep in a 24 hour period, why don’t they just have it in one big chunk at night like adults do?
Remember that sleep serves a biological function for growth and repair as our body slows down and regenerates for the next day. So for babies and children who are growing at such rapid rates, their sleep needs will be higher, but they also need to eat, interact and learn so their sleep is broken into various sleep periods versus one VERY big one.
Another very important fact to note is that our bodies NEVER sleep in one big chunk! Did you know that even you as an adult wake multiple times throughout the night. The only difference between children and adults is we have had many years of practice putting ourselves back to sleep when we wake throughout the night you don’t even remember doing it most of the time. Babies and young children are learning this very important skill and often wake fully as they search for help to get back to sleep until they can do it on their own. The reason why we wake multiple times is something called a sleep cycle.
There are several anthropological studies that explore the possible evolutionary reasoning behind sleep and night wakings and they conclude that we require sleep cycles to ensure we are protected from danger. If we went straight into deep sleep, where our sensory systems significantly slow down, and we stayed in this state for our whole sleep we wouldn’t hear a startling noise that may alert us to danger, we wouldn’t hear our crying infant who needs us in the night, our muscles would relax too much and we would be very stiff when we eventually woke.
What does a sleep cycle look like?
Babies and young children have smaller sleep cycles than adults and are more easily fully aroused when they cycle through their sleep throughout the night. Adults have larger sleep cycles as our brain structures in charge of controlling sleep have fully matured. The saying, “sleep like a baby” was most definitely coined wrong as babies do not sleep soundly at all!
So, lets look at a sleep cycle to begin to understand what happens when babies, children and adults sleep. Below is a simplified breakdown of one sleep cycle.
As you can see sleep is broken into several stages where different activities happen in the brain to promote various systems to complete tasks while we sleep. Adults sleep cycles are 70-90 minutes long as our limbic systems (the sleep control centre) is mature. In children however, their limbic systems are immature and their sleep cycles are often shorter 30-40 minutes.
Did you know newborns are the only stage of human development that does not cycle through these normal phases of sleep! Newborns cycle between only two sleep states - deep and active/light sleep – every single time they sleep until around 4 months of age. This is also known as the onset of the “4 month sleep regression” as babies now suddenly have proper sleep cycles! As children grow and mature their cycles of sleep begin to sync more with adults and their ability to sleep for longer periods improves as they learn to connect sleep cycles without needing to fully rouse.
Once an infant begins to move into cycled sleep you may notice that they suddenly wake up after 30-40 minutes of sleep and are fully awake! We can sometimes worry that our child is going to be a perpetual catnapper because they don’t seem to be able to sleep for longer than that. This is actually a very common side effect of infants progressing into adult-like sleep cycles. As these sleep cycles are so new, children can take time adjusting to the new arousal and deep sleep states. As the child develops their limbic system and practices “linking/connecting sleep cycles” they are able to return to sleeping longer stretches of time at once.
Homeostatic Sleep Pressure
A very important factor in our ability to sleep and our ability to reach deep sleep is something called homeostatic sleep pressure. You can physically feel this pressure building throughout the day as your eyes begin to get sore and your energy levels are dropping. We can push this pressure away temporarily with stimulants such as coffee and refined sugars but in the end sleep pressure will always win!
There are several hormones and environmental factors that contribute to sleep pressure. Utilising our understanding of the environmental factors contributing to sleep pressure can help us to support a good nights sleep for our children. Exposure to natural light (especially late afternoon sun), minimizing exposure to blue light within an hour of bedtime (blue light is emitted by most technology screens), being physically active for at least 30 minutes a day, having a consistent bedtime routine to cue sleep. There are many other factors but that is just to name a few.
Children’s bodies build sleep pressure more quickly than adults as their bodies and brains are growing, consuming more calories and they are significantly more physically active than us. These factors all contribute to increasing our child’s need to sleep and although they may fight it… sleep pressure always wins!
It is this sleep pressure that also creates our children’s need to nap. The more sleep pressure they have built up the more they need to sleep to reset the balance. Interestingly, children also need to build up adequate sleep pressure in order to nap more restoratively. Too little and they won’t sleep for long and feel unrested, too much sleep pressure and the nap may be un-restorative. In order to approach this balance of over and under-tiredness there are periods called “wakefulness windows” that can be followed as a guide to help understand when a child may need to sleep.
Below is a common recommended window of wakefulness for different age groups:
Age of child Average time awake Approximately naps per day
0-3 months 35 minutes - 90 minutes 6 down to 4 naps per day
3-5 months 75 to 120 minutes 4 down to 3 naps per day
5-10 months 2 to 3.5 hours 3 down to 2 naps per day
10-14 months 3 to 4 hours 2 down to 1 naps per day
14-24 months 4 to 6 hours 1 nap per day
3-5 years 6 to 12 hours May still take 1 nap but most children will transition away from day naps
*these wake times progressively increase with age. For example, a 3 month old’s window of wakefulness will be on the lower end of the range (75-85 minutes) and as they reach 6 months old they would start aiming for the upper end of the range (90-120 minutes).
Children are really good at letting you know when they need to sleep through their behaviour and physical reactions as well. Looking at a combination of wake windows and sleep behaviour cues can allow you to pinpoint the best times for your child to go to sleep.
Sleep cues for a baby/infant may be:
• rubbing eyes,
• crying,
• irritability or
• yawning.
While toddlers sleep cues can be:
• increased challenging/defiant behaviour,
• irritability,
• yawning,
• rubbing eyes.
Preschooler aged children have the language to express how they are feeling and are better at regulating their sleep behaviours so their cues are often more verbal but don’t forget they will still rub their eyes, become irritable and challenging just like younger children.
In the next instalment of this sleep series we will look at:
• Understanding Sleep attachments/associations
• Dummies and Cuddly Toys and role they play in sleep
• Bedtime routines
• Strategies for when something seems to be going wrong