Decades of studies on the importance of sleep in brain development and maintenance have given us a very good idea of the need for a decent amount of Shut-Eye.
Now American researchers have overcome our understanding of the major functions of sleep by developing a mathematical model that shows how we go through changes in sleep behavior as we leave the child behind for years.
“I was surprised at how big a change this is in a short period of time, and this switch happens when we’re so young,” says Van Savage, an ecologist and evolutionary biologist at the University of California, Los Angeles.
“It is an infection that occurs when water freezes ice.”
While sleep is something we all personally experience on an almost daily basis, there is still something we do not understand. Just to make matters worse, the closer we look, the more complex this function seems.
Savage and his team wrote in their report, “Assuming that sleep has evolved to perform some primary function, it is almost certain that many physiological functions have an extensive and time-consuming feature of animal life.”
A major part of the sleep process is to enter the state of consciousness by the transfer of our eyes as we dream, called Rapid Eye Movement (REM).
In adults, it kicks in at intervals of about half an hour, when we nodded, and seems to be locked into our memory banks by associating them with the consolidation we experienced while awake.
Sleeping newborns spend about half of their time in this state, while by the age of 10, the REM stage becomes the cause of about a quarter of their sleep. This memory-building dream phase is included with age 50, as well as less than 15 percent of the sleep duration.
We can imagine that infants need BEM sleep above their developing brain, packing it with experiences that will help them walk on the ground after finding their feet.
What’s going on the rest of the time, then? This down time is a good chance for the body to do a normal sweep of the detergent and be repaired. Not getting enough of it seems like a good way to collect waste that increases the risk of future neurological damage, such as dementia.
But for all we know about sleep patterns, we are short on comprehensive models that can help us understand how and why it evolved in the first place.
Combining their expertise in neuroscience, biology and mathematics, researchers used data from dozens of sleep studies to discover how the general relationship between REM sleep and time spent in body shape develops.
They found evidence of a connection in body mass in relation to increased amounts of sleep time. In younger humans, the brain grows faster than the rest of the body, requiring a lot of attention to the building connection.
Yet the relationship between brain development and maintenance needs is proportional. Once the brain is more or less formed, sleep should be done mostly in relation to its size.
Preliminary measurements from three other animals were also included, which provide some insight into the development of rabbits, mice, and guinea pigs.
The analysis revealed a surprising amount of continuity across species with the potential for REM sleep deterioration over the developmental similarity of humans over two and a half years. This change is so well preserved that it suggests that its function may be important for mammalian development.
It is too early to draw any strong conclusions from the model on mammalian development in general, or know if it can be applied even more widely to other animals.
But taking a mathematical approach in this way suggests that a major transition in the primary purpose of sleep is a normal stage of development throughout the animal kingdom or if the human child mind is particular in this regard.
“During that period the mind is really surprising and very different,” says Savage.
“In terms of our ability to learn languages or adapt our minds to different situations, what are the consequences?”
There is a lot going on inside that little head. Just one more reason to make sure that they and you – get good sleep as often as possible at night.
This research was published in Science advance.