Dehydration

‘Electricity in your head. Feel your head going, it’s as if it’s not there – as if the head part is not quite secure. It’s a peculiar feeling.’ anon 2009

The human body is about two-thirds (approximately 70%) water. Water is essential to the normal working of your body. It lubricates the joints and eyes, aids digestion, flushes out waste and toxins, and keeps skin healthy.
Dehydration occurs when the normal water content of your body is reduced. This leads to a change in the vital balance of chemical substances in your body, especially sodium (salt) and potassium. In order to function properly, many of the body's cells depend on these substances being maintained at the correct levels.NHS choices website