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The Cycles of Sleep

The Cycles of Sleep

The R90 approach simply means Recovery in 90 minutes. Ninety minutes is the length of time it takes a person under clinical conditions to go through the stages of sleep that constitute a cycle.

Our sleep cycles are composed of four (or sometimes five) distinct stages, and it’s easy to think about our passage through a cycle as being like a journey down a flight of stairs. When we turn the lights off and get into bed at night, we’re at the top of the stairs. Down at the bottoms of the stairs is deep sleep, which is where we want to get to.

The Top of the Stairs: Dozing off

Non-REM (NREM) Stage 1

We’re slowly taking our first couple of steps down the staircase, and we’re somewhere between awake and asleep for a few minutes. Have you ever jerked awake suddenly because you’ve imagined yourself to be falling? That happens here and it’s just a hallucination, but it means we need to begin our descent down the stairs again. It’s very easy to pull us back up the stairs from here – a door opening, a voice in the street outside will do it – but once we manage to negotiate this stage successfully, we make our way down to…

The Middle of the Stairs: Light sleep

NREM Stage 2

In light sleep our heart rate slows and our body temperature drops. From here, we can still be dragged back to the top of the stairs by someone shouting our name or, in the case of a mother, her baby crying. We spend the biggest percentage of our time asleep in this state, so it can feel like a long flight of stairs at times, particularly for those getting stuck in light sleep, but it isn’t time wasted if it’s part of a well-balanced cycle. Information consolidation and improved motor-skill performance is linked to this stage, and as we move further down we begin the transition to the really good stuff.

The Bottom of the Stairs: Deep sleep

NREM Stage 3 (and 4)

Congratulations. You’ve reached the bottom of the stairs. Down here, it takes a good deal of effort to wake us. Our brain produces delta waves, the slowest-frequency brain waves (we produce high-frequency beta waves when we are awake) in deep sleep. We want to spend as much time as we can down here, wallowing in it, as this is where we reap the major physical restorative benefits of sleep, such as the increase in our release growth hormone. We hope to spend around 20% of our time down here in deep sleep during the night.

Helter Skelter: REM

In the Beatles’ song ‘Helter Skelter’, they sing of going back up to the top of the slide, where they stop and turn and go for a ride. It’s not too dissimilar to this stage of sleep. We head back up the stairs, to light-sleep territory for a while, before we reach a stage of sleep many of us are familiar with: REM (Rapid Eye Movement). This is where our mind takes us off on a ride – we do most of our dreaming in this stage while our bodies are temporarily paralysed, and REM sleep is believed to have beneficial effects on creativity. We need to get back up towards the top, stop and turn and go for a ride every bit as much as we need to get to the bottom of the stairs, and again, we should be looking to spend around 20% of our time in this stage. At the end of the REM stage we wake – we usually won’t remember this – before beginning the next cycle.  

Each cycle during the night is different. Deep sleep accounts for a higher portion of our sleep in earlier cycles, as our body prioritizes getting this as soon as it can, while REM sleep accounts for a higher portion in later cycles. However, if we have been getting less sleep than normal, our brain will drop into REM for longer in earlier cycles, demonstrating its importance to us. This is just one of the reasons why ‘catching up’ on sleep – by going to bed earlier than normal or sleeping in later – is a waste of your time. Once sleep has been lost, it’s gone. But our bodies are remarkably good at doing our catching-up for us.

Ideally, we would spend a night in bed smoothly making the transition from one cycle to the next, in a pattern of sleep-wake-sleep-wake… gradually getting less deep sleep and more REM sleep as the night progresses, until our final wake in the morning. This is the key to getting the right quality of sleep: all the light sleep, deep sleep and REM we need in a series of cycles which feels to us like one long continuous night’s sleep.

However, there are all sorts of obstacles in our way: noise, age, stress, medication, caffeine, physical disturbances like a partner’s leg touching us, breathing through our mouths instead of our noses, snoring and sleep apnoea, temperature and the necessity of a bathroom visit can bring us back up towards the top of the stairs and leave some of us doomed to spend too much of the night in the lighter stages of sleep, or takes us out of our cycles entirely.

The knock-on effects of this can range from growing levels of daytime fatigue to fatal consequences. Our bodies can dump us straight down into a micro-sleep during the day when we least expect it, such as when driving a car or operating a piece of machinery.

If we’re trapped in light-sleeping patterns then it doesn’t matter how much sleep we’re getting – we’re not benefiting from it fully. The R90 approach tackles the obstacles that stop us getting down the stairs. 

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