Neuroscience Of Sleep

One of the most persistent topics that often holds humanity’s interest is the actuality and purpose behind their own biological functions. Many hold a desire to grasp and understand the concepts of how their body and brain works, and the evolutionary purposes behind every facet of the human existence. Among the most explored functions exists the process of sleep, one of the most mysterious quirks that have puzzled evolutionary biologists for generations. While many understand some basic science associated with sleep, the average person knows so little about the neurological and physiological science and purpose behind it. Many levels of comprehension and theory exist past the layman’s understanding of what sleep is and why it exists. Even though

scientists continue to search for answers, nobody understands every single facet of sleep’s function and the reasons of why animals sleep in the first place. One can understand sleep more completely if they comprehend the neurobiological functions associated with it, as well as the various reasons that sleep exists.
When one thinks of a person sleeping, they often just think of an unconscious person lying down in a bedroom. They often neglect to think about what exactly is going on in their brain during this process. The long-held myth that the brain had no activity during sleep has long been dispelled, and everyone knows of the brain’s activity during nightly rest. These activities are a complicated series of stages that even scientists do not know everything about yet. Robert Stickgold nicely summarizes the general patterns of sleep and the electrical brain activity associated with it in his article “Neuroscience: A memory boost while you sleep.” Stickgold explains that human sleep is divided into two main phases: rapid-eye-movement, abbreviated as REM, and non-rapid-eye-movement, abbreviated as NREM (559). While many know that these patterns are divided simply by eye movement during sleep, there is actually more evidence to support this division. These two phases are evidenced by patterns of electrical activity in the brain, which has been measured and studied by scientists. Waves known as theta waves oscillate at a rate of 4-8Hz, and are exclusive to indicative of REM sleep (Stickgold 559). The first stage of non-rapid-eye-movement sleep is a phase that transitions between a person’s full wakefulness and sleep. This stage includes waves of mixed frequency. Sleep spindles, waves that oscillate at a rate of 12-14Hz, are indicative of the second stage of NREM sleep (Stickgold 559). Delta waves, waves oscillating at a rate of 1-4Hz, occur in stages 3 and 4 of NREM sleep. These stages are known collectively as “slow-wave” sleep (Stickgold 559). Sleep spindles and delta waves are accompanied by slower oscillatory patterns, potentially less than 1Hz, which are classified as cortical slow oscillations (Stickgold 559).
One may wonder what the importance lies in studying the various stages of sleep. Many people just view sleep as a continuous activity with no further division and classification, when in reality, studies show that sleep is much more layered and transitional than that. The different speed of brain oscillations shows how our brain activity slows down and speeds up during different stages of rest. A much deeper process is at work here; a process of dynamic brain activity and function. The more scientists study these dynamic and complicated functions, the better they can understand sleep and its purpose.
The patterns of electrical brain oscillation can even be pushed to be understood further.

In their article “The cognitive neuroscience of sleep: neuronal systems, consciousness and learning,” Allan J Hobson and Edward F Pace-Schott attempt to further study brain functions during sleep and unearth their implications. Studies have shown how that the electrical patterns of rest are generated from subcortical and cortical regions within the brain (Hobson and Pace-Schott 680). These generations are not only found in human brain functions, but across many different species of animals. From the transition of waking to NREM sleep, almost all neurons show a decrease in firing, most likely resulting from the different activities that occur in the brain in the front regions of the brain, coming from the brainstem (Hobson and Pace-Schott 680). These activities are possibly influenced by the hypothalamus and circadian rhythms, meaning that waking neurological functions can have an influence and interference on the patterns that occur during sleep (Hobson and Pace-Schott 680). Neurons fire at a similar rate of waking activating during NREM sleep. The thalamus’s influence over the brain activities show themselves to be one of the biggest influences over sleep’s change in consciousness from waking activity, demonstrating how waking functions and separate areas of the brain hold a strong connection to functions occurring during sleep (Hobson and Pace-Schott

681).
Hobson and Pace-Schott go on to discuss how consciousness and dreaming relates to brain activities. They hypothesize that, contrary to popular belief, dreams do not occur strictly in an REM state. This is evidenced by the fact that dream-like functions and hallucinatory states are evidenced in stages of sleep outside of the REM phase (Hobson and Pace-Schott 684). However, since REM sleep has the best environment and highest likelihood to produce a dream-like state, it is the most convenient phase of sleep to use when studying consciousness and attempting to synthesize a dreaming model (Hobson and Pace-Schott 684).
Hobson and Pace-Schott and others’ studies of neurological functions of sleep, and what exactly influences its phases and electrical activity, has led to a greater understanding of sleep’s purpose and functions outside of relatively simple oscillation patterns.

Their dispelling of the myth that dreaming is exclusive to REM sleep paints a picture of a more complex dreaming phase, suggesting that it is not as linearly and stagnantly linked to consciousness as one may think. This further shows a fuller picture of sleep being a dynamic process that many continue to still study and understand. The better one understands how sleep occurs and the different patterns that are seen during rest, the easier one can ponder why animals sleep in the first place and why it is

important
In the article “Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise,” by Hugh HK Fullagar et. al, the concept of sleep’s importance is discussed. Athletic performance of athletes is hindered by loss of sleep. While many consider mental performance to be supported by sleep, they rarely consider physical performance as well. While it is true that athletic performance can be seen as a mental as well as a physical task, studies have shown that exercising is not as easy or efficient when one loses sleep (Fullagar et al. 161). Numerous studies on the loss of sleep show slower cognitive function and responding when one receives less sleep the night before a task (Fullagar et al. 161). In the article “Poor sleep and psychiatric symptoms at school: an epidemiological study,” E J Paavonen et al. discusses how sleep loss can lead to psychiatric problems later in life. A random sample of over 5,000 eight-to-nine-year-old children were selected from a variety of schools. The parents’ and the childrens’ report of sleep problems were both taken into account when considering how badly each child experienced sleep deprivation (Paavonen et al. 10). Psychiatric symptoms were evaluated by the students’ teachers by the Rutter B Scale. The study found that the children who experienced severe sleep problems also had more symptoms of psychiatric problems. Severe sleep problems were correlation with emotional problems, behavioral problems, and hyperactivity (Paavonen et al. 10). This study clearly illustrates how important sleep is to avoid sociological and psychiatric issues. The less sleep one receives, the less likely they are to behave optimally. While these studies do not take into account the children’s growth into adulthood, the misbehavior of children of young age is often indicative of more problems as one grows older.
All of these studies show how important sleep is. Without sleep, one experiences emotional, behavioral, and memory-related declines. Sleep was probably developed in order to avoid all of these issues. The brain is meant to sustain a waking cycle accustomed to circadian rhythms and hypothalamic patterns, not one of constant waking and working. Animals evolved a system of sleeping to avoid the deterioration that comes with a waking mind’s expenditure of resources and mental energy. Nobody knows the one true reason why animals sleep, but it is clear that it serves a very valuable purpose and that the benefits that come with sleep greatly outweigh the drawbacks of depriving oneself from it. Without sleep, humans would be emotionally, behaviorally, and physically handicapped.
The greater understanding of sleep is an extremely important aspect that every person should take the time to understand. While the depth and complication of neuroscience may be off-putting to some, one must at least comprehend the dynamic nature of sleep, and how there are many external and internal influences on its various functions. Despite numerous studies and time put into research, scientists still do not understand everything about sleep or why it occurs. The further studying of sleep will allow everybody, not just the elite scientific community, understand it more completely. Many hold a burning desire to discover everything they must about their own brain and its functions, and sleep is a staple of it that humanity cannot and will not remain completely undiscovered.