Appliance of science: Why do we dream?

Dr Naomi Lavelle offers up some more scientific answers to your questions

WHEN it comes to dreams people have very different opinions; some say they never dream, some remember every detail. Then there are those that debate the why, how, and when of dream. Regardless of what you think about dreaming, you may be interested in some of the theories on why we dream at all.

THREE TYPES OF DREAMS

There are three basic types of dream, regular dreams, lucid dreams and nightmares. Regular dreams occur when we are in a deep sleep. Lucid dreams usually occur during a lighter phase of sleep; we are at least partially aware that we are dreaming and we can often consciously change the course of the dream.

SLEEP AND DREAMS

There are five stages of sleep, stages 1, 2, 3, 4 and the rapid eye movement (REM) stage. We usually move into deeper sleep as we pass through each stage and while we do dream in each stage, it’s thought that most of our dreaming is done during REM.

Studies have shown that we tend to have different types of dreams at each stage of sleep; very short dreams are associated with the earlier stages of sleep and these are more realistic and relatable in nature. As we move into deeper sleep our dreams tend to become more obscure and disjointed.

THE WHY OF DREAMING

There are a number of theories as to why we dream, each based on scientific studies. Some say dreaming is an asinine activity that serves no purpose, but most agree this is not the case, although they may argue as to the true value of dreams.

Let’s start with the activation-synthesis hypothesis, the notion that dreaming serves no purpose. Followers believe dreams are simply electrical brain impulses firing off as we sleep, pulling random thoughts and images from our memory.

Then there is the threat stimulation theory (TST) favoured among many evolutionary biologists. Basically this theory states that dreams are the body’s way to prepare for potential danger, by simulating threatening situations through dreams that trains us to overcome the dangers posed. And all this happens while we sleep, so if we ever do find ourselves in similar danger in real life, we have already gone through the training process.

The next theory is that dreams help us solve problems; our brain gets to work things out without some of the distractions passed by the activities of our waking hours. Perhaps the most famous case is that of the chemist August Kekule, who supposedly discovered the benzene ring structure after dreaming of atoms linking together in a chain and then twisting, like a snake biting his own tail, into a ring structure.

Not surprisingly the famous neuroscientist and father of psychoanalysis, Sigmund Freud, believed that dreams were merely manifestations of our unconscious desires.

Some sleep studies have reported high level of brain activity in an area called the amygdala, an area of the brain associated with emotions. This has led to another theory that dreams allow us process emotions without necessarily having to relive the emotional events.

Finally, dreaming may be important in the process of laying down memories. MRI studies have shown that brain areas associated with short and long term memory consolidation (the hippocampus and amygdala) are activated while we dream.