What are the stages of your sleep cycle?
Sleep scientists estimate that most of us should experience around 4-5 sleep cycles a night, and, during these cycles, your body will move through different stages of NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement) sleep.
These sleep stages are extremely important – your body needs them to rest and repair. Certain sleep stages can even dictate what hormones are released and impact psychological functions such as empathy and mood!
So what are these different stages of sleep and just what are they doing for your body?
Stage One – NREM 1
The first stage of sleep is sometimes known as ‘NREM 1’ or the ‘transitional stage’ and the chances are you’re very familiar with this phase of sleep. Your brain waves will be shifting from alpha state, a relaxed, calm state, to theta waves, which normally occur when you feel deeply relaxed or during meditation.1
During this stage you will be feeling drowsy although it’s still very easy to rouse someone from NREM1 and sometimes they can be jerked awake by a loud noise or movement. It’s also the stage of sleep where you experience muscle twitches or jolts, which can sometimes make you feel as though you are falling.
Although generally, you’re only supposed to spend 5% of your total sleep time in stage one, if you suffer from insomnia or stress, you may spend longer in this phase.
Stage Two – NREM 2
In the second stage of sleep your breathing and heart rate will gently start to slow down and your body temperature will decrease. Eye movement will stop and, aside from quick bursts of waves known as ‘sleep spindles’, your brain waves will slow, preparing you for deep sleep.
You can still wake someone up from NREM2 but they are more likely to recognise that they were sleeping, rather than nodding off. You will spend around 50% of your time sleeping in this second stage which usually lasts around 10-20 minutes.
What are sleep spindles?
Sleep spindles are brief bursts of activity and recent research has even indicated that sleep spindles could be related to your ability to learn. One study found that the more sleep spindles that were produced in napping the subjects, the more refreshed and able they were to perform learning tasks.2 This seems to imply that too little sleep in NREM2 could impact your ability to learn and retain knowledge!
Stage Three & Four – NREM 3 & 4
In 2007, the American Academy of Sleep Medicine combined the third and fourth stage of sleep, which is why some refer to there being 4 sleep stages and others 5. Since very similar functions occur during these stages, sometimes known as ‘deep sleep,’ I’ll try and talk about both collectively.
During stages 3 & 4 slow delta brainwaves will start to occur and your blood pressure will slowly drop. It’s very difficult to rouse someone from deep sleep and, if you do awaken suddenly from this stage, you may feel groggy and disorientated for quite a while.
This is the sleep stage where your body will repair itself and it can last for up to an hour; during this stage hormones such as HGH (Human Growth Hormone) are released and the blood supply to your muscles will increase.3 This stage of sleep is also extremely important for your immune system, which you can find out more about in Dr Jen Tan’s blog ‘How does sleep affect the immune system.’
Interestingly, NREM 3 & 4 are also the stages during which you are most likely to experience sleep walking and night terrors.
Stage Five – REM sleep
REM sleep is sometimes referred to as ‘dream sleep’ and it the stage where you will start to dream. Your brain activity will start to increase, as will your heart rate and blood pressure.
It’s an incredibly important stage of sleep for your memory and emotional health – dreams can help you to hone your survival instincts and work through emotional issues as well as regulating what memories get committed to short and long-term memory. If you want to learn more, please read my blog, ‘The dangers of dream deprivation.’
What happens if you miss a stage?
The amount of time of spend in a particular sleep stage can vary, depending on factors such as your age or when you go to bed. The likelihood of missing an entire sleep stage though, is very rare as in general, it’s difficult to break a sleep cycle. The more likely scenario is that you will experience a disruption to a stage of sleep.
For example, if you are woken up in the middle of stage 4 sleep, you can expect to experience the typical symptoms of sleep deprivation and well as sleep inertia. On first waking up, you will feel tired, groggy and have impaired cognitive ability but if this disruption is an on-going issue, you may notice that certain aspects of your health are affected, such as your immune function, mood and digestion.
This is why it is very important to try and deal with the issues that could be causing the disruption, whether it’s stress, insomnia, a nasty bout of the flu or your diet. All can contribute to poor sleep so make sure you practice a good sleep hygiene routine before bed and keep a healthy, balanced diet.
If you still find yourself struggling to nod off or waking up during the night, you could try our gentle stress remedy Dormeasan. Dormeasan is prepared using extracts of organically grown Valerian and Hops, and can help to gently regulate your sleep pattern. Unlike most conventional sleep pills, Dormeasan is a non-drowsy formula and is best taken 30 minutes before bedtime.
“I have trouble sleeping, after taking this I slept like a baby.”