What are the four stages of sleep?
We all know that sleep is good for us. Studies have long demonstrated the link between rest and our overall health – which, in turn, can often make us reflect on our own habits. Whether we’re getting too much or not enough is one thing, but many of us also pore over the quality of sleep we’re getting, as well as what goes on when we do get some shut-eye.
A new study has revealed that our routine – more specifically, when we go to sleep – is equally as important. Those who fail to stick to regular bedtimes are, according to the research by UK Biobank, 26% more likely to suffer from stroke, heart attack or heart failure than those who do.
The key is consistency, with the aim being to "wake up and go to sleep within 30 minutes of the same time each night and each morning, including weekends," says the study's lead author, Jean-Philippe Chaput of the University of Ottawa. So, a routine when it comes to adult sleep, just like with babies, is crucial.
To help improve our sleep and our habits around it, a good place to start is looking at – and understanding – the four stages of sleep. Of course everyone is different, and some nights it’s easier to drift off than others, but generally speaking, by knowing what these steps are, we can better prepare ourselves and encourage improved sleep.
The stages of sleep – explained
NREM Stage N1
Typically lasting between 1-7 minutes, stage one is when a person first falls asleep. Although your muscles and brain activity start to relax during this stage, you are not fully asleep yet. It is easy to wake someone up in this stage of sleep and those who are awakened at this point may not register that they were asleep. But, if left undisturbed, they can usually transition to stage 2 quite easily.
NREM Stage 2
As well as experiencing a drop in temperature, people tend to be much more relaxed in this stage of sleep – their heart rate and breathing slows as a result. Eye movement also stops and general brain activity slows, as your body gets ready to enter deep sleep. This stage usually lasts around 10-25 minutes.
NREM Stage 3
It is during this final stage of non-REM sleep that your body starts to undergo important, restorative functions. It bolsters your immune system and triggers recovery and growth.
As you enter deep sleep, it is much harder to wake up. Your muscles, pulse and breathing rate relaxes significantly and your brain activity calms during what is referred to as the delta or slow-wave sleep. This stage typically takes between 20-40 minutes.
REM Stage R
Lasting around 10-60 minutes, the final stage of sleep – REM – is where brain activity picks back up, as does eye movement, breathing and heart rate – though muscle movement is still low, beyond the occasional twitch. It is the dreaming stage of sleep and takes up around 25% of your total time asleep.
Throughout the course of a night, you will go through four to six cycles in total – and you may wake up in between, even if for a brief moment.
Read more on sleep
The exact time you should go to bed, according to sleep experts (Yahoo Life UK, 6-min read)
Here's What It Means If Your Teeth Fall Out In Your Dreams (Huff Post, 2-min read)
How to get a better night’s sleep at any age (Yahoo Life UK, 6-min read)
