YOUR BRAIN ON SLEEP
Sure, it might feel like you’re out for the count on your stateof-the-art mattress (Simba versus Eve: discuss), but there’s an awful lot going on under the hood. See above – the hills and bumps on the graph depict your brain’s activity over the course of an average night. ‘We can identify four main stages of sleep,’ says sleep specialist Dr Sophie Bostock. ‘A sleep cycle is made up of the body passing through the three stages of non-rapid eye movement (NREM) sleep and back to
REM sleep, before beginning the next cycle,’ she explains. Let’s give it a spin.
STAGE ONE
‘In this stage, where you’re just losing consciousness, it’s very easy to wake up again,’ says Dr Bostock. When you’re tucked up in bed, you’re likely to spend about 10 minutes in this very light sleep before falling into stage two.
NREM SLEEP STAGE TWO
Proper toasty-underthe-duvet AKA ‘true’ sleep, where your heart and breathing rates slow and body temperature drops until you fully lose consciousness. ‘It’s probably where you’ll spend most of your time asleep,’ says Dr Bostock, with between 20 and 30 minutes typically spent in this phase until you go on to the next.
STAGE THREE
The most physically restorative phase of sleep, stage three is referred to by scientists as slowwave sleep (SWS). You might be out for the count, but your body’s hard at work secreting growth hormones from the brain and helping cells to re-energise and repair. If you’ve done a long run that day, you’ll require more of this kind of slumber.
REM SLEEP
Rapid eye movement sleep, so called because your eyes are flicking about all over the shop, is the phase normally associated with dreaming, where your brain is pretty active. ‘The electrical brain activity of someone who’s awake is actually very similar to that of someone in REM sleep,’ says Dr Bostock.
AND... REPEAT
Rather than just progressing consecutively from SWS to REM, you’ll reverse back through the NREM phases, transitioning from light sleep to REM before starting the next cycle back in stage one. Simple, eh?