You may not know it, but there’s a lot going on in your body and mind while you sleep.
In fact, there are five stages of sleep which you cycle through not once a night, but usually between four and six times.
We’ve taken a look at each of the five stages to see exactly what is going on while you’re away in the land of nod.
This is that stage where you’re only just drifting off or waking up naturally and as such it’s the lightest stage of sleep.
This stage only lasts between five and ten minutes, and basically just serves as a transition between sleep and wakefulness and allows your body to wind down and your muscles to relax.
Now that your body is slowed down, your brain follows suit in Stage 2 as your heart rate starts to slow down, as well as your breathing and you start to become disengaged from your surroundings.
Your body temperature will also start to drop as you start to approach the completely relaxed state needed to drift into deep sleep.
This is the beginning of what we know as “deep sleep”, and the brain begins to really slow down into what are known as “delta-waves”, interrupted by slightly faster “beta-waves”.
If you get woken up during this stage you’re likely to be groggy and confused.
Stage 4 is the deepest of the sleep stages, and the brain exclusively experiences delta-waves.
This is the stage where you’ll take the most waking up, and its also where children are most likely to suffer from bedwetting and night terrors.
On the plus side though, the body uses this stage to restore damage and carry out most of its restorative work on any tissue damage.
Stage 4 is also likely to be the longest of the sleep stages, lasting around an hour.
Stage 5 is actually the only stage where we dream, and is perhaps better known as REM (Rapid Eye Movement) sleep.
REM sleep is characterized by random eye movements, and increased blood flow, breathing and brain activity.
In fact, brain scans show that the brain is almost as active during this stage of sleep as it would be while awake.
One of the stranger aspects of REM sleep is that your arm and leg muscles may become temporarily paralyzed.
This may be to stop us physically acting out our dreams, and could also be linked to sleep paralysis (which we discussed in another blog post).
As you go through the sleep cycle numerous times through the night, your REM stage gets progressively longer, starting out at 10 minutes and ending up lasting about an hour.
How long you spend in the REM stage also depends on age, for example while adults will usually experience it for 20-25% of the time they are sleeping, for a baby it is closer to 50%.
So there you have it. Who knew so much was going on while you lie there apparently unconscious?
There are now sleep apps such as Sleep Cycle which aim to monitor your sleep and ensure that you wake up at the end of a sleep cycle, so that you wake up feeling refreshed and as you would do waking naturally.
As we learn more and more about the sleep cycle hopefully we’ll be able to more accurately measure how much sleep we need, and improve our sleep health all round.