Sleep - the land of dreams

Have you ever wondered what happens when you go to sleep? Why we dream of the things we dream? Well this weeks New Scientist helped to clear up our misconceptions on sleeping and dreaming as the cover page story (spanning an astonishing 10 pages) dealt with the mechanisms of the brain while we relax and fall into the embracing arms of our dreams.

So what is happening while we sleep? During the sleeping period, complex changes occur in the brain which when observed using an electroencephalograph (electrodes that join onto the skull to track brain activity) showed that 8 hours of sleep is actually divided into 4 cycles which are repeated over and over again. Stage 1 lasts between 5 to 15 minutes and is essentially the awake stage as it is the time taken to fall asleep. Stage 2 is often characterized by falling sensations and jerking muscles that awake us during the night, but is mainly the time when fatigued muscles are allowed to rest and our alertness is replenished. The next stage (stage 3-the slow wave sleep) is essentially more important as it carries out the major changes and thus people waking up during this period often feel groggy and disorientated, reducing their alertness, attention, concentration, judgement and problem solving.

And more importantly what are dreams? According to a recent study done whereby people were woken up during their sleep in order to ensure they remembered details about their dreams we rarely ever encounter our senses. According to the study our dreams are mostly to do with sight with very little use of sound or touch. 

It is now thought that perhaps this has to do with how our mind deals with our memories, which are processed in 2 stages. First memories are moved across the hippocampus, something like the human memory's printing press, and then they float into our concious, re-emerging several days later filling the inner cortex. This also helps to explain why we don't see full scenes and events but only pieces of our memories, with the order signifying how our memories are re-packed. A recent study conducted in Arizona, found that places seem to dominate dreams as they are most remembered, followed by characters, actions and finally physical objects. This helps to explain why we sometimes dream of different events and places not seen in years. 

Another experiment conducted at the Univeristy of Surrey (UK) found that people who hadn't slept for 29 hours had an excess cound of white blood cells in the blood indicating the importance of sleep So what does this all mean? It just goes to show how important sleep is in life however many questions till remain and there is much more we still need to discover to clear this mysterious subject.