Some science into our Dreams!

The weird animal having an elephant head, a giraffe’s long neck, and the body of a horse has been chasing you all the way from the mountain top to your favorite pizza restaurant and suddenly you jump into a chocolate pond! You open your eyes in a horrific jump and yell” Oh! It was just a dream! Now, what is this ‘dream’? Are they ‘just’ dreams? Let’s wonder.

So, What are Dreams?

Dreams can be thought of the happenings, images, or stories which our brain pictures when we are asleep. According to the National Sleep Foundation, an average person dreams four to five times in an eight-hour sleep each night. Each dream may last more than thirty minutes in the late nights. Experts say that occurrence of dreams is more likely in the REM(Rapid Eye Movement) phase of the sleep cycle. This REM phase lasts for the quarter of your sleep time occurring in about every 1.5-2 hour intervals. But then interestingly, children below 10 years of age dream in NREM(Non Rapid Eye Movement) phase of sleep. During sleep, dreams are indicated by high-frequency electrical activity in the brain.

Why don’t we remember our dreams?

Studies show that there are mainly two reasons why we don’t remember our dreams. First, When we are sleeping, the brain doesn’t stop functioning completely, instead, some events put the brain to sleep in stages i.e step by step. Researchers say that the Hippocampus (Hippocampus is a brain structure embedded deep in the temporal lobe of each cerebral cortex) is one of the last regions to go to sleep. Incidentally, Hippocampus plays a critical role in converting the information in the short term memory to the long term memory. If Hippocampus sleeps late then it is most probably a late riser region. When you wake up with a dream, the dream is in the short term memory now, and is not converted to long term memory because the Hippocampus is not fully awake and not ready.

Second, Two neurotransmitters, Acetylcholine and Noradrenaline are important for retaining memories. During sleep, levels of these two neurotransmitters decrease. During REM stage, initial acetylcholine levels return,almost taking us to a state of wakefulness. But, levels of noradrenaline stays low thereby reducing our ability to recall the happenings in a dream.

Do Animals Dream?

Like people, REM stage was observed in almost all mammals from cats and rats to horses. In a sleep study published in the journal Neuron in 2001, scientists Michael Wilson and Kenway Lovie of MIT- Massachusetts Institute of Technology researched on rats. They made rats run through a maze in search of food and made them sleep. They compared the brain patterns of rats running through the maze with their brain patterns during REM sleep afterward. The brain of the running rat created a distinctive pattern of neurons firing in the Hippocampus known playing an important role in the memory. They found that two patterns were amazingly similar that they could tell which of the maze the rats where dreaming of and whether the rats were still or running. And Wilson says “One theory regarding the role of dreams in memory is that dreams may provide the opportunity to bring together experiences that were related, but did not occur at the same time, in order to learn from them,” Wilson said. “For example, replaying a series of pleasant or unpleasant experiences may allow us to learn what these experiences had in common and use this to guide future behavior.”

Studies have shown that humans learning repetitive tasks can use REM sleep to enhance performance. In some cases, this “in dreams” practice session seems to be as good as practicing the tasks when awake. Tests have shown that both rats and humans are better at a recently learned task after a period of sleep. “It has been a century since Freud brought forward the study of the subconscious and the examination of the content of dreams as a tool for understanding the nature of cognition and behavior in humans,” Wilson said. “We now have the means to bring this world of dreams into the study of animal cognition, and by doing so, gain deeper insight into our own.”

Grey scale dreams

In this colorful real as well as virtual world it will be strange to know that some people dream in black and white. But yes, Most of the elderly people are found to dream in black and white, while most of the younger generation seem to have dreams in color. Researchers say that it might be due to exposure to black and white television to the elderly and the emergence of color televisions for the younger generations. 12% of the population is known to dream in greyscale.

Psychologist Eva Murzyn from the University of Dundee, UK has asked 60 subjects to fill the dream diaries after waking up. Half of the subjects were above 50 years of age while the remaining were below 25. Dream diaries were filled early in the morning as there were issues of subjects reporting that they couldn’t remember the color in the dreams as the day passed. Results were as following 

(i) 4.4% who were under 25, had their dreams in black and white

(ii) 7.3% of the people who were aged above 55 and had access to color television and film during childhood had dreams in black and white

(iii) Subjects who were above 55 years and had access to only black and white television dreamt in black and white for a quarter of the time. 

Very less percentage of people dream in grey scale in a population.

“There could be a critical period in our childhood when watching films has a big impact on the way dreams are formed,” she says. Even though they would have spent only a few hours a day watching TV or films, their attention and emotional engagement would have been heightened during this time, leaving a deeper imprint on their mind.

Michael Wilson of MIT says that this new ability to eavesdrop on the sleeping brain provides a basis for analyzing the content of dream states. It could be a valuable tool in treating memory disorders such as amnesia or Alzheimer’s disease, or it may help devise ways for people to learn and memorize more effectively.