In today’s busy and hectic society many see sleep as a luxury rather than what it is – a necessity. More and more people are working overtime, and shift work trying to juggle a busy family life around their work. Along with this, it is not unusual for both parents to be working full time. The advent of our 24/7 society has pushed regular sleep to the side. Because of this, many men and women (and even children) wrongly consider sleep a waste of time.
Sleep is an essential element of the human body, without it we cannot survive. Getting enough sleep is associated with energy, joy, optimistic thinking and coping with negative emotions. Despite this almost 90 percent of Australians suffer from some type sleep disorder at some stage of their lives. Of these, 30 percent suffer from severe sleep disorders. Very few people regularly enjoy the amount or quality of sleep that they need. The estimated economic costs to the country from this are between $3 billion and $7 billion annually. There are also huge, unmeasured physical, psychological, emotional and social costs.
Sleep is complicated in the way that there are many different factors that influence the effectiveness of sleep. It’s not just duration that determines the effectiveness of said sleep, factors such as quality, frame of mind and deepness all contribute to the maximum desired outcome and even our perception of how we sleep. Many factors can play a part in the quality and quantity of our sleep and to maximise our sleep time an understanding of this is essential.
On average a healthy person will spend around one third of their life sleeping (Duman et al, 2009). Sleep is considered a natural periodic state of rest for the mind and body, in which the eyes will usually close and consciousness is completely or partially lost resulting in a decrease in bodily movements and responsiveness to external stimuli (Blanch et al, 2009). Inadequate hours of good quality sleep leads to a disruption to vital biological processes resulting in a decrease in cognitive function mental and physical health (Anderson et al, 2009) including impaired work performance due to a decrease in attention, judgement and responsible decision making (Volkow, 2009).
Why we sleep
Mammals are naturally diurnal animals and sleep for humans are broken into two distinct phases. These phases, Non Rapid Eye Movement (NREM) and Rapid Eye Movement (REM), represent the depth of sleep and electrical activity in the central nervous system (CNS) (Cirelli & Tononi, 2008). However, sleep is a heightened anabolic state where rejuvenation of many organ systems occurs, especially the immune and nervous systems. NREM is further broken into phases one to three during which have different waves of sleep and cognitive perceptions, phase one for example is associated with hyper‑CNS responses. During this phase the body may quickly jerk out of steep and this will be felt as a falling sensation (Walsh, 2009). Various genetic mutations have been associated with sleep including DEC2 mutations that lower the sleep requirement from eight hours to six and the 600072 prion gene that predisposes to Fatal Familial Insomnia (Kniff in, 2009; McKusick and Kniffin, 2009). The natural circadian rhythms of the body are a result of variations in levels of circulating melatonin hormone, from the pineal gland, and also adenosine levels which increase over the course of the day (Imeri & Opp, 2009).
Among the theories on why humans sleep, scientists have proposed the following:
Sleep may be a way of recharging the brain. The brain has a chance to shut down and repair neurons and to exercise important neuronal connections that might otherwise deteriorate due to lack of activity or over activity.
Sleep gives the brain an opportunity to reorganize data to help find a solution to problem, process newly learned information and organize and archive memories.
Sleep lowers a person’s metabolic rate and energy consumption.
The cardiovascular system also gets a break during sleep. People with normal or high blood pressure experience a 20 to 30% reduction in blood pressure and 10 to 20% reduction in heart rate.
During sleep, the body has a chance to replace chemicals and repair muscles, other tissues and aging or dead cells.
In children and young adults, growth hormones are released during deep sleep (World Federation of Sleep Research and Sleep Medicine Societies
Immune function is highest when we sleep
Detoxing. There appear to be “hidden caves” inside the brain, which open up during sleep, allowing cerebrospinal fluid (CSF) to flush out potential neurotoxins, like β-amyloid, which has been associated with Alzheimer’s disease. The research discovered “hidden caves” inside the brain, which open up during sleep, allowing cerebrospinal fluid (CSF) to flush out potential neurotoxins, like β-amyloid, which has been associated with Alzheimer’s disease. The interstitial spaces in the mouse’s brain took up only 14% of the brain’s volume while it was awake. Yet, while it slept, this increased by almost two-thirds to take up fully 23% of the brain’s total volume. The effect is that potential neurotoxins, like β-amyloid, are cleared twice as fast during sleep as during waking. While many neurological diseases, like strokes and dementia, are associated with problems sleeping. It could be that lack of sleep, and restriction of the brain’s cleaning system, may cause toxic metabolites to building up, leading to long-term damage.
Most likely we sleep for a combination of these reasons
Part 2 and more coming