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When the lights go out

By Marion E Brooks-Bartlett, on 21 June 2012

Sleep illustration

Sleep illustration by Matteo Farinella

Have you ever wondered what happens the moment you close your eyes and go to sleep? Did people give you this vague understanding of ‘it’s the time when your body gets to rest’?

Well, following Hans Berger’s invention of the Electroencephalogram (EEG) in 1924, we have been able to measures brain activity and we can now see that the brain is actually very active during sleep.

This brilliant invention displays waves with respect to time and and show that when you are in an awake state a ‘beta’ wave is produced  (frequency ~12-30 Hz), then you relax and alpha waves are produced at a frequency of 8-12 Hz. You then enter a theta state when you’re sleeping (freq. 4-8 Hz), and before you know it, you’re in a deep sleep producing delta waves on the EEG (less than 4 Hz).

This is not the only thing, though. From 1953, scientists started using an electro-oculogram (EOG) to analyse eye activity and the results, combined with those from an EEG, showed that our eye and brain activity during sleep is not too dissimilar to when we are awake. What can be distinguished is that when you dream, you experience Rapid Eye Movement (REM).

So what does this all mean for us? Well, now that we can measure the moment that people start sleeping and then the moment when they start dreaming, I can tell you that apparently, we dream about five times every night, though we might not recall them, and they last between 5-45 minutes, with the last dream lasting the longest (about 40 mins).

We have approximately a 5-7 second window to recall the dream before we forget it (I hate that – especially when it’s a good dream and I’m receiving accolades for being the world’s best scientist and… yeah right!). People tend to remember the most bizarre dreams and five percent of our dreams are about animals.

What was really enlightening about this talk by Professor Richard Wiseman, a psychologist from the University of Hertfordshire, was the selection of videos that he showed of people sleepwalking and making themselves a cup of tea while asleep. He also mentioned a whole family that got up while they were asleep and sat round the dinner table together.

Probably the worst thing that people can suffer from is a night terror. If you think you’ve had a nightmare, take that as being mild. Apparently, sleepwalking and night terrors occur during the time that delta waves are showing up on the EEG – this is when you’re in your deepest sleep.

The video we saw of a night terror showed a man that got up screaming and then jumped over his bed from left to right, and you could just sense the fear in him. This is quite different to acting out your dream.

So much was mentioned and this talk was incredibly informative, so just a few more points for those anxious to know: that feeling you get when you want to wake up but can’t move because you believe that some demon or evil force is holding/attacking you is called ‘sleep paralysis’ – the type of evil spirit usually depends on someone’s cultural beliefs.

You dream in real-time, so when you recall a dream it’s generally of the order of the length of time you were dreaming it. Then there’s pre-cognitiveness, which is when you dream about the future and things like natural disasters – scientists are not too sure of the validity of these, though some may be true. Richard  is sceptical about the idea of ‘levels’ in dreams – lucid dreaming is about as far as it goes. So no Inception-style adventures for us!

Ricahrd and his team released an iPhone app last year called called Dream:ON, which helps to affect the way you feel when you wake by playing music at a particular time when you’re sleeping to influence your dream. It also invites you post a short description of your dream to their experimental Dream Bank, which contains a huge number of them already.

Please check out Dream:ON at the Apple App Store.

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