Let’s talk sleep cycles!

A sleep cycle refers to the stages of sleep during each cycle.

For infants and toddlers, during the day, a sleep cycle lasts 45 – 50 minutes. Overnight, it is between 2 – hours.

Sleep is broken into non-REM and REM sleep:

Non-REM sleep:

  • Also known as deep sleep, is very important for restorative sleep, physical growth and repair, cell repair, and metabolism regulation.

  • This is when your infant or toddler appears to be sleeping peacefully and still (a parent’s dream).

  • There are 3 stages to non-REM sleep and as you progress through each stage, you go from the lighter stages of sleep, into deep sleep.

REM Sleep:

  • Also known as active sleep, is when they are in a lighter stage of sleep.

  • It is during REM sleep that memory consolidation occurs, and this is very important for infants and young children, who are growing, developing and learning new skills.

  • During REM sleep, they can appear restless, which can often be confusing to parents as they may think their little one has started to wake up.

  • It is also during this time that they are easily woken.

At the end of a sleep cycle, your infant or toddler has a partial waking. During this time, they will check their environment (to make sure nothing has changed), re-position, they may look for their comfort item such as a toy or soother. During this time, they may even cry out or start making noises or movements that make it seem that they are actually awake, such as sitting up (which can be very confusing for parents). This partial waking can last anywhere from a few seconds to a couple of minutes.

At the end of this partial waking, they will either fully wake or transition into their next sleep cycle.

Why the wake could be due to many factors:

  • They have had enough sleep and are simply no longer tired.

  • They have a sleep association that needs to be repeated in order to go back to sleep.

  • Their sleep pressure at nap or bedtime was low which can result in a short nap (or waking 1 – 2 hours after bedtime at night or for older children, awake for longer periods overnight).

  • They were overtired at nap or bedtime. When they are overtired, this can cause a rise in cortisol which can result in not only difficulty settling to sleep, but also staying asleep.

Sleep cycles overnight:

After 3 - 4 months of age, children will enter non-REM sleep first and relatively quickly, transition into deep sleep. It is during this time that they are difficult to wake and most often, appear to be sleeping peacefully. This sleep cycle lasts approximately 90 - 120 minutes and after that time, they will have a partial waking. This partial waking may last a few seconds or a few minutes. And during this time, they may sit up, roll around, open their eyes, or even cry out. Following this, they will have a period of light sleep, before they transition into another deep, non-REM sleep cycle.

This explains why infants and children usually spend the first 3 - 4 hours in very deep sleep (and why it may seem like they happen to wake right when you are about to go to bed yourself).

As the night progresses, they transition between non-REM and REM sleep, with progressively longer periods of REM sleep. Even when in non-REM sleep in the second half of the night, they spend more time in the lighter stage of non-REM sleep. And this is why it is common for parents to be confused as to why their child can sleep well in the first half of the night, but wake during the second half.

It is during these lighter stages of sleep and when transitioning between sleep cycles that frequent wakings can become an issue. Furthermore, as their melatonin levels naturally start to decline whilst cortisol levels start to increase in preparation for waking up for the day, it re-settling back to sleep can become more challenging.

If you are having issues with short naps, frequent nighttime wakes, or you are just feeling overwhelmed by all things sleep, Little Slumber Sleep Consulting is here to help you.

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