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What they are:
'Brain Waves' are the minute recorded variations in voltage taken from pairs of electrodes placed upon the skull and face. You can do this with an EEG, whether one of the old ones with reams of paper and ink, or the newer models that cost 150,000 dollars and are essentially a low powered Dell with a big monitor and lots of specialist cards and amp boosters.
The two predominant varying factors are the amplitude and frequency of the waves : -
|
| / | /| | ^
| / | /| / | /| ( ) height is Amplitude
/ \ | | | \ | | | |
/---\---- /---|-------|--\-----/---|-------| |
\ / \ / \ / \ /
\ | | | \ | | |
| / | / | / | /
|^ \/ |^ \/
--- rapidity is frequency ----
Through the use of conventions, these have been classified for a variety of purposes, including sleep research, medical
diagnosis, broader research into bioligical rhythms, biofeedback, nuerofeedback and all forms of crankery.
The common wave type conventions :
Alpha - The relaxed wave, one sought by meditators the world over. Close your eyes, don't attempt to solve any partial differential equations, and you'll probably exhibit these. A low amplitude, fairly high frequency wave.
Beta - You're awake and doing stuff with your eyes open. Welcome to the real world, Beta style. A fast low amplitude wave, you'll also see it in your dreams, because that's the part of sleep where you're just a different type of awake.
Theta - A slower, somewhat higher amplitude wave seen in various stages of sleep, as well as the waking state of those unfortunate to be suffering from too much cypress hill upside the head (injury/illness).
Delta - Sweet, sweet Delta. High amplitude, low low frequency. This is the Barry White of waves, seen in (and used to classify) the deepest stages of sleep (SWS 3 & 4). Ohhhh baayyby.
What they aren't:
Brain waves won't tell anybody what you're thinking, dreaming, trying to mind control, the imminent tin-foil hat plans of the alien overlords, or the methods which the government are using to make your cat spy on you. Each of the wave types can be hard enough to spot that sleep stage classification is more art than science at times.
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