Humans have a long way to decoding the enigma of the human brain. The human brain, unlike that of any other animal, is capable of tasks that cannot be expected from even the advanced forms of artificial intelligence (AI). For a company to design an artificial intelligence system as complex as the human brain would require an algorithm involving billions of networks and the simple yet complicated ability to make CALCULATED DECISIONS. A calculated decision must have a reason, conscience, and the ability to foresee the consequences of the decision taken. An artificial system may conjure up a reason for action but may be unable to do it with a conscience and/or understand its repercussions.
The human brain differs from that of the other animals as it comprehends needs beyond the need for nutrition, safety, and reproduction. Our brain is driven by opportunities and gain, yet it is never satisfied. So, for such a deviously genius character, how can it not accomplish the task of recollecting dreams?

Why do we dream?
Dream psychology and sleep medicine are unpredictable fields as all the situations (as incurred by the brain) cannot be imagined in the laboratory. However, dreams are a sign of a healthy brain. The animal in the vicinity – such as dogs, cats, and cows – are also capable of dreaming; so can babies and people who have acquired blindness.
The concept of dreaming has been described as a way of keeping one part of the brain engaged (during sleep) as the other part actively processes the events of the day to judge which memories should be promoted from being short-term to long-term memories. No matter how dramatic or unforgettable the dream was, the memory leaves the brain within 120 seconds of being awake. Dreams are fabricated by the brain – unlike experiences and memories – and yet the brain chooses to forget them.
Those who remember their vivid dreams explain it to be like a movie – fast-paced, adventurous, and long – however, most dreams are only a few seconds long. The way we remember our dreams may not just be the dream but instead the emotions we associate with the dream which fills in these blanks. Since dreams are fleeting, so is our ability to recall them.

Why do we don’t remember our dreams?
Scientifically, we can dream in two states – during REM SLEEP and NON-REM SLEEP. REM sleep refers to the sleep where we engage in rapid eye movement (REM) and can last between 90 minutes after falling asleep to one hour before naturally waking up. The dreams we have during non-REM sleep may be remembered since they occur in a state where the person may be awake, but the dreams during REM sleep are difficult to recollect. Often, people who report not having dreams are unable to remember them. Various theories have been put forward to explain this and have been narrowed down to acceptable ones.
1. HIPPOCAMPUS
The hippocampus is a structural component of the brain involved in learning and memory. When a person goes to sleep, most of the parts of his brain not in use are shut off and put to sleep as well – the last one being hippocampus. The hippocampus is known to reduce a portion of its activity a few minutes after the rest of the brain does. If this logic is applied to when a person wakes up, scientists have found that the hippocampus is also the last part of the brain to get active.
During REM sleep, the hippocampus – being the region essential for memory – sorts through memories and eliminates the ones which are not required. While it is still active, its other part is inactive – which forms new memories. Hence, when a person wakes up, their dreams dissipate because of the lag caused due to the hippocampus.



2. NEUROTRANSMITTERS
Neurotransmitters are molecules which enable the transfer of message across NEURONS via a chemical path. The levels of neurotransmitters acetylcholine and noradrenaline varies throughout sleep and play a role in memory retention.
As a person goes to sleep, the levels of both the neurotransmitters drops. However, when the person enters REM sleep, the level of acetylcholine increases, which allows the occurrence of the dream. The production of acetylcholine tends to activate the CORTEX of the brain, thus enabling a dream. Noradrenaline remains inactive and hence, the events of the dream are not stored.
3. Unnecessary memories
Dreams are deemed unnecessary by the brain. During REM sleep, dreams are crucial as they ensure the hippocampus is active, but the other parts are distracted. Yet, dreams are momentary and avail no benefit to the brain or the person later. Hence, even if the memories associated with the dream are stored in the brain, they are eliminated.
This does not just occur with dreams. Elimination of unnecessary memories is an essential function of the brain – which may occur when we are awake as well. The exact memories of brushing our teeth or taking a shower are also eliminated.
Is it possible to recollect dreams?
Majority of the people can recollect some elements from their dreams. These dreams may have been during the non-REM sleep or the person may have an exceptional memory. Scientists also say that nothing is truly lost in the brain. If an event related to a forgotten dream occurs while the person is awake, the brain can get triggered to recollect it. People who choose to keep a dream journal also tend to remember their dream more than those who do not keep one.

Humans do not need to remember their dreams, but the inherent curiosity of humans causes us to chase this wild goose. Dreams range over a variety of concepts and as per many people, reflect the psyche of the person. Inculcating simple habits can boost memory and enable recollection of dreams but stressing over the same can cause more harm than good.