why we dream ?

Tucked in your bed, wrapped in the blanket, in the middle of the night, a series of thoughts and emotions passes through your mind, while you are asleep. Now you are entering the mysterious and fascinating world, where the rules of reality don’t apply. Yes! You are right. It’s the DREAM. You are dreaming now, because your subconscious is speaking to you, while you are asleep. That means your brain is active at night, revealing your deepest thoughts, feelings and fears.
Theory of dream:

It is difficult to explain the function of dreaming. Despite many theories, scientists still do not completely understand the purpose of dreaming. What we do know so far is that dreaming is a way of sorting and shuffling various events that happen during your waking hours.
A dream is nothing but the succession of images that pass through your mind during sleep. Perhaps dreams are our way of confronting our lives and dealing with things. Our brain pulls out information and incidents and sorts them through memories and deciding, which ones to retain and which ones to lose.
The best explanation is the psychosomatic theory of dreams. It suggests that dreams are a product of ‘disassociated imagination’, which is dissociated from the conscious self and draws material from sensory memory for simulation, feedback resulting in hallucination. In other words, dreams are vivid representations of repressed urges.
REM Dreaming stage:Photo: IainPolysomnographic record of REM sleep, which provides data regarding electrical and muscular states during sleep. EEG highlighted by red box. Eye movement highlighted by red line.
Human sleep consists of six recurring stages that are independent of one another. These includes four non-REM stages, one REM stage and the waking stage as the last one. The most vivid dreams occur during the REM (Rapid Eye Movement) stage of sleep - the normal stage of sleep with rapid movement of the eyes.
About 4-5 periods of REM sleep occur during a normal night of sleep. The eye movements at this stage are associated with PGO Waves (Ponto-geniculo-occipital waves), and are generated by the pontine nucleus with projections to the major component of the vertebrate mid brain, called superior colliculus. In this stage, respiration and heart-rate speed up resulting in increased brain activity, muscular immobility and a change in the neuromodulatory systems.
Does REM sleep occur in all mammals?Photo: Andrew.Beebe
We all know that every species shows some form of sleep. Studies so far show that REM occurs in most mammals. Even dolphins exhibit some sort of REM sleep. During slow-circle-swimming, they allow half their brain to sleep at a time.
But what about reptiles? Being common ancestor of birds and animals, we might expect that reptile must show REM sleep. But this is not true. Reptiles don’t have brain development like mammalians and also do not have a neocortex. Therefore, they don’t exhibit REM sleep. Even if they did, it would be quite different from that of mammals. More studies are needed to prove it.
Photo: Who dreams the most?
Studies suggest that the percentage of REM sleep is the highest during early childhood. It means the more immature a person is, the more dreams they would have. In other words, the smaller the animal, the more REM sleep. (Read more about the sleepiest animals).
Therefore, cats, dogs, pigs and of course humans all dream. But koalas and brown bats are the winners as they might be dreaming a lot. And, who dreams less? Giraffes and elephants sleep very little - only 3-4 hours a day. Thus, they might dream less.
Lastly, even though we dream a lot, within 5 minutes of waking, most of it is gone. It is a common tendency to forget 90-95% of our dreams. In closing, a quote about dreams that sums it up well: “The best thing about dreams is that fleeting moment, when you are between asleep and awake, when you don't know the difference between reality and fantasy, when for just that one moment you feel with your entire soul that the dream is reality, and it really happened.”