The strange world of dreams
Some people are more capable of remembering their dreams, some less. But we all dream every night. While we are dreaming we do not know that we are dreaming, do we? We undergo the most bizarre dream experiences without judging them or wondering about them. Only after waking up do we find out that everything was just fantasy. But the border between waking and dreaming is not as sharply drawn as you might think.
Lucid dreams
For it can happen spontaneously that you become aware that you are dreaming. Perhaps you recognise a dream you've had before, but not only afterwards, but during the dream. Suddenly you are able to judge the dream events, to become aware of absurdities and bizarrness while they are happening. As a rule, lucid dreams are more colourful and lively as normal dreams and they are easier to recall. Possibly you have even access to your true memories. Once you are aware that you are dreaming there is basically the possibility to influence the dream events. Interestingly it has been found out that two things are very difficult to realise during lucid dreams: changing brightness (turning on or off a light) and reading (the words don't make any sense or change).
False awakening
Although you normally have no access to your power of judgement during a dream you should at least be able to realise without a doubt that you have woken up. - Wrong. Quite a lot of people have apparently woken up, had breakfast, got dressed and left for work or university only to find out - after actually waking up - that it was just a dream. False awakenings can happen several times in a row. What is different to a plain dream during which you just dream that you are waking up somewhere and going to work somewhere is that the dream events occur just the way they occur in real life. The dream is a quite accurate reproduction of reality. Moreover you believe to remember yourself sleeping and dreaming shortly before, but are sure that you are awake now. Finally, you may also have access to your true memories.
Sleep paralysis
Imagine yourself waking up in your bed not able to move. You are clearly aware of your surroundings and you are sure to be awake. You feel the mattress you are lying on, the blankett covering you. With a little luck this paralysis is over after a few seconds and everything is back to normal. Though, it may happen that during this paralysis you have the feeling that a weight is pressing down on your chest. You have difficulties breathing. Maybe you hear strange sounds, maybe voices. You see some form or strange lights. But perhaps you have just the uncanny sensation of somebody being in the room. You are in panic and try in vain to move. Suddenly the "visitation" is over.
This experience is called sleep paralysis. In some cases it is accompanied by hypnopompic or hypnogogic hallucinations. The sleep disorder is as harmless as it is frightening. You can learn to end this state by carefully trying to move a finger and concentrating on waking up.
It makes sense that we are unable to move while in dream state. Otherwise we would live out our dreams and maybe hurt ourselves or others. Sometimes this paralysis already starts before we are fully asleep or continues when we are about to wake up. Sometimes this state is accompanied by hallucinations or dream images that are influenced by fear.
The term night-mare derives from this experience. People used to think that they were haunted by goblins, succubi, inccubi or witches. Every culture has its own myth relating to this phenomenon, e.g. "Old Hag" in the New Foundland area. Nowadays, a striking number of people with symptoms matching those of sleep paralysis report having been visited or even abducted by aliens.
Book tip
If you want to know more about the background of lucid dreams, sleep paralysis and similar phenomena, I can recommend the book "Lucid dreaming" by Celia Green and Charles McCreery ($ 18.99, Routledge, ISBN 0415112397). It summons up the scientific findings of the last decades and provides many reports by experiencers.