This topic was requested by one of our educators as they wanted to learn more about the basics of sleep, sleep cycles, patterns and requirements for healthy sleep.
This is quite an interesting topic as it has so many facets and differences with each individual child and family. There are also cultural differences from around the world that can play a role in the requirements of sleep. All of these factors come into play when we and our children sleep and there are mountains of information on sleep so I will do this blog in installments. This first installment will explore:
- What is sleep?
- Sleep Cycles and how they impact on our children’s sleep/wake patterns
- 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! Sleep is the consolidation of our day; it is theorised that during sleep we process our thoughts, emotions and sort memories to clear our minds for more information.
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”. So, for our young children they need sleep more often and more of it as their brains are bombarded by new information all day every day and their brains need time to consolidate it all!
Another important factor in sleep is the release of Human Growth Hormone (HGH) when we enter deep sleep. This hormone in children allows their bodies, brains and tissues to grow and repair. The old wives tale stands true “you grow in your sleep!”
So, we have established that sleep is important. So how much do our children need?
The National sleep foundations sleep recommendations for a 24 hour period (includes naps in total amount required) are:
- Newborns (0-3 months) between 14-17 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 and your child may fall outside of these times on average. 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 getting to know your child’s needs is the best way to assist them to get better sleep overall.
So, if our child needs loads of sleep, why don’t they just have it in one big chunk at night?
Sleep serves a biological function for growth and repair as our body slows down and regenerates for the next day. However, if we didn’t have sleep cycles to bring us in and out of sleep we may never wake up!
There are several anthropological studies that explore the possible evolutionary reasoning behind sleep 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.
To cut a looooong story short, we need sleep cycles to maintain safety and for biological purposes (i.e. twitching to maintain muscle movement, dreaming for information consolidation etc.)
What does a sleep cycle look like?
Below is a simplified breakdown of one sleep cycle.
Adults sleep cycles are 70-90 minutes long as our limbic systems are mature. In children however, their limbic systems are immature and their sleep cycles are shorter 30-40 minutes. Newborns are the only stage of human development that does not cycle through these normal phases of sleep.
Newborns cycle between two sleep states - deep and active/light sleep - every time they sleep until around 4 months of age, this corresponds strongly with the startle reflex which is a part of their active/light sleep cycle. As children grow and mature their cycles of sleep begin to sync more with adults and their ability to sleep for longer periods improves.
Once an infant begins to cycle their sleep you may notice that they wake up after 30-40 minutes of sleep! We can sometimes worry that our child is going to be a 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 sleep cycles” together 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!
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 and their sleep may be un-restorative. In order to approach this balance there are periods called “wake windows” that can be followed as a guide to help understand when a child may need sleep.
Below is a common recommended window of sleep for different age groups:
|Age of child||Average time awake||Estimated naps per day|
|0-3 months||45 minutes -1 hour||6 down to 4 naps per day|
|3-6 months||1 to 1.5 hours||4 down to 3 naps per day|
|6-9 months||1.5 to 2 hours||3 naps per day|
|9-12 months||2 to 3 hours||2 naps per day|
|13-24 months||3.5-5 hours||1 nap per day|
*these wake times progressively increase with age.
Children are really good at letting you know when they need to sleep through their behaviour 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 are more often 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.