Novel methodologies are helping scientists unravel the mysteries of our brains, providing a better understanding of sleep cycles, dreams and brain activity.
Read on to find out about the known facts as of 2020.
As modern neuroscience has discovered, sleep follows a very precise mechanism and evolves in 90 minutes cycles on average. Each of these sleep cycles includes three clearly identified phases: calm awakening or light sleep, then deep sleep and finally REMS.
REMS (Rapid eye movement sleep), as amazing as it may sound, is truly occurring multiple times every night! This is the phase when neuroscientists belive our most exciting dreams occur.
For now scientific experimentation cannot yet prove a subject in a period of REMS is dreaming. But empirical experience shows 85% of people remember their dream when awakened during this phase, versus only 10% to 15% during deep sleep.
It is estimated that humans dream 100 minutes on average every night. Thus a 60 year old will have spent about 5 years of his or her life dreaming within a total of 20 years sleeping!
These sleep cycles differ as the night progresses: initially slow and deep sleep phases are longer and REM sleep is at its shortest. Later during the night the slow sleep and deep cycles shorten, whereas the REM phase becomes longer.
This is why the length of our consecutive nightly dreams increases. Our first dream in the night lasts just about ten minutes, then the second one about twenty minutes, while the following dreams last half an hour. These last dreams are the ones best remembered, as they take place at the end of the night, when we are about to awake.
We always best remember our dreams when we just awake, as they are still in our short-term memory, which only keeps the very recent past in our mind. For us to really remember a dream, it must reach the long-term memory part of our brain, which normally does not happen. It will only happen when we write down the story of the dream, so has to have a record of it. By thinking about a dream we had, it will then more easily be remembered.
Another notable fact is that the first hours of the night provide more rest, where both the body and the brain are mainly resting and dreaming less. As if the biological priority was to rest at first, and only dream if time permits after the body is rested.
Dreaming and remembering it
Humans are not all equal when it comes to dreaming. As a matter of fact we don’t all have the same capability for dreaming or for remembering our dreams.
Thus, women seem to dream more than men. Waking up during a REMS phase, 95% of them remember what they were dreaming, compared to only 80% of men. They are also able to give a more detailed account of the events, which seem to last longer. Women are also more prone to nightmares than their male counterparts.
Researchers today have no scientific explanation for this phenomenon. At most, one can draw a parallel with the fact that women are often endowed with a greater emotional imagination than men and therefore may be more inclined to dream in a rich and detailed manner.
We don’t dream the same way at all ages.
It is very complicated to determine from what age a child begins to dream and specialists do not agree on that. It seems that in the first months, even the first years of life, the baby and the child are rather victims of night terrors, a phenomenon which is not akin to dreams and which occurs during slow sleep rather than during sleep within REMS.
For a child to begin to dream, he must have the maturity necessary to realize that it is a dream and that he has the vocabulary to tell it. Otherwise he cannot interpret his dreams.
Age and ability to dream
It therefore seems that the ability to dream increases in the first months of our life, as does all of an individual’s cognitive abilities. Conversely, this ability to dream would also decrease with age and seniors would have fewer dreams than adults in full bloom of age. Again, impossible to generalize or have certainties, but two elements support this hypothesis.
Seniors often sleep for shorter durations than younger people. However, as was said, REM sleep lengthens over the night, during the third and fourth cycles. It is therefore likely that the elderly simply have less REM sleep available to them to dream.
Like other organs, the brain ages and rusts with age. Neuronal plasticity decreases, that is to say that the neurons become less adaptable, the connections between them are sometimes less potent. This is why it is more difficult to learn new things as you get older than when you are a high school student or a student. In the same way, this lack of plasticity could play a role on the imagination and dreams.
Serious research on dreams began in the 1950s, which made it possible to highlight the particularities of REM sleep as well as its functioning. The majority of researchers believe nowadays that most of the dream in its successful form takes place during the REM phase.
At the end of the 19th century, Edmond Goblot launched an inverse theory, taken up more recently by neurobiologist Jean-Pol Tassin: we would dream during short periods of wakefulness, between two sleep cycles. A theory that they defend thanks to the existence of the famous alarm clock dreams where the external stimuli, which eventually wake us up, are integrated into the dream.
Evolution and the ability to remember as well as the ability to tell our dreams come from the effectiveness of these neurons that we all have by the billions. This neural mechanism varies according to age and sex, but everyone goes through the same sleep.