Chris Idzikowski (Director of the Edinburgh Sleep Centre) gives expert video advice on: Why do we dream?; What is a dream?; Does everyone dream? and more...
Why do we dream?
I've no real idea why we dream at all. I just interpret perceived dreaming as an awareness of oneself during rapid eye movement sleep, which is the dream state. During rapid eye movement sleep the brain is almost as if it's awake. But because most of the centers are pretty much disconnected, there are little bits that are working but not pass the information up. You're free floating in whatever the brain's trying to do at that point. So I think cultures have ended up interpreting dreams in a variety of ways and the interpretations vary on the cultural, the time point in that culture, so I have no real idea of what they mean at any one point in time.
What is a dream?
I think for the most part one would always regard dreaming as that bizarre visual confused imagery one gets during sleep. But if you're talking to a blind person who is congenitally blind then they may experience the dream in a completely different way. So it wouldn't be visually driven, it would be driven by another sense.
Does everyone dream?
Everybody has Rapid Eye Movement sleep. Dreaming is gaining an awareness of oneself whilst one's in that REM state, and that's what is dreaming about. Now, dreams are highly evanescent; they may last momentarily after an awakening. So 20, 30, 40 seconds after waking up after Rapid Eye Movement sleep and dreaming, the odds of remembering that state are extremely low. So most people who say that they can't dream -- it just means that they've gone into light sleep, and have woken a while after Rapid Eye Movement sleep. For the majority of people, if they simply set their alarm clocks for 15 minutes earlier than normal, and go to bed thinking to themselves, "I'm going to recognize what's going on in my head when the alarm goes off," they should recognize that they're actually in a dream state. I would recommend a gentle alarm clock.
What can stop you dreaming?
With a stroke, those centers that actually generate the state of rapid eye movement sleep may be destroyed. They're not very common, but they do occur. Or one can get a variation, instead of having highly visual vivid imagery and intensely colored dreams, those dreams can become darker and less vivid and so on. One gets a gradient of effects from strokes, but they are there.
Do we dream every night?
Rapid eye movement sleep occurs every night, so dreaming can occur every night.
Can you manipulate another persons dream?
It is possible to manipulate dreams by providing some stimulus externally. I'd almost say an emotional stimulus, something that is most relevant to the person is most likely to get in without waking the person.
Do we have more than one dream a night?
One has roughly four rapid eye movement, perhaps five rapid eye movement bouts during the night, so that number of potential dreams during the night and some people would say they're aware of the dreams running right through the night. So they could actually go through one REM episode into the next. For that reason there's no reason why one shouldn't have more than one dream. In fact, where subjects have been awoken during rapid eye movement sleep the first REM episode is quite short and very often people say they weren't dreaming, that mentation is really quite dull and not that interesting. In the second REM episode it does get a little bit more vivid, thus more likely to get a real dream report and it is not until the third fourth episode that's really getting lots of dreaming going on.
Why do we only remember some dreams?
I suspect the difference between nights is all probably almost one to do with body temperature more than anything else. Body temperatures partly correlated with alertness and awareness of what's going on and just slight variations in body state are enough to create a difference.
Do we ever have the same dream twice or more?
Unfortunately, post-traumatic stress disorder dreams are recurrent nightmares. The two are tied together. Yes.
What is the difference between dreams and nightmares?
A nightmare is a dream but one that is associated with lot of negative thinking and emotions and reactions.
Why do some dreams become nightmares?
The thing about rapid eye movement sleep is our physiology is hugely uncontrolled at that time. So big changes in heart rate and respiration and so on. How one interprets the motion depends on the context, the context of that emotion. So if I go back to work I used to do on parachuting, I used to say you can research either fear or euphoria with parachutists in early jumps but when you're looking at the physiology of the emotion it was very similar for both and a run of experiments showed that depend-- [SOUND GOES OUT ON VIDEO AFTER THIS]
Do we dream in black and white or colour?
The veracity in the colors associated with the dream can vary from really being very vivid to just monotone.