What is the effects of sleep deprivation and chronic lack of sleep?
- Fatigue, lethargy, and lack of motivation
- Moodiness and irritability
- Reduced creativity and problem-solving skills
- Inability to cope with stress
- Reduced immunity; frequent colds and infections
- Concentration and memory problems
- Weight gain
- Impaired motor skills and increased risk of accidents
- Difficulty making decisions
- Increased risk of diabetes, heart disease, and other health problems
- Sleep-deprived people who are tested by using a driving simulator or by performing a hand-eye coordination task perform as badly as or worse than those who are intoxicated.
- Sleep deprivation also magnifies alcohol's effects on the body, so a fatigued person who drinks will become much more impaired than someone who is well-rested.
- Driver fatigue is responsible for an estimated 100,000 motor vehicle accidents and 1500 deaths each year, according to the National Highway Traffic Safety Administration.
- Caffeine and other stimulants cannot overcome the effects of severe sleep deprivation. The National Sleep Foundation says that if you have trouble keeping your eyes focused, if you can't stop yawning, or if you can't remember driving the last few miles, you are probably too drowsy to drive safely.
- Activity in parts of the brain that control emotions, decision-making processes, and social interactions is drastically reduced during deep sleep, suggesting that this type of sleep may help people maintain optimal emotional and social functioning while they are awake.
Sleep disorders costing Australia $5.1 billion a year
A new economic report commissioned by the Sleep Health Foundation released on 2 Feb 2012 reveals sleep disorders cost the Australian economy more than $5.1 billion a year in health care and indirect costs. In addition, the reduction in life quality caused by sleep disorders has a further cost equivalent of $31.4 billion a year. The report, 'Re-awakening Australia – The Economic Cost of Sleep Disorders in Australia' highlights more than 1.5 million Australian adults, 9% of the adult population, now suffer from sleep disorders, including sleep apnoea, insomnia and restless leg syndrome.
According to Proffessor Hillman, chairman of the Sleep Health Foundation, about 5 % of heart disease and high blood pressure and 10 % of depression is attributable to sleep disorders.
"And then of course workplace accidents and productivity losses and for that matter losses of life quality.
What happens to my brain when I sleep?
Neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells in the brain. Neurons in the brainstem, which connects the brain with the spinal cord, produce neurotransmitters such as serotonin and norepinephrine that keep some parts of the brain active while we are awake. Other neurons at the base of the brain begin signaling when we fall asleep. These neurons appear to "switch off" the signals that keep us awake. Research also suggests that a chemical called adenosine builds up in our blood while we are awake and causes drowsiness. This chemical gradually breaks down while we sleep.
During sleep, we usually pass through five phases of sleep: stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. These stages progress in a cycle from stage 1 to REM sleep, then the cycle starts over again with stage 1.
We spend almost 50% of our total sleep time in stage 2 sleep, about 20% in REM sleep, and the remaining 30% in the other stages. Infants, by contrast, spend about half of their sleep time in REM sleep.
During stage 1, which is light sleep, we drift in and out of sleep and can be awakened easily. Our eyes move very slowly and muscle activity slows. People awakened from stage 1 sleep often remember fragmented visual images. Many also experience sudden muscle contractions called hypnic myoclonia, often preceded by a sensation of starting to fall. These sudden movements are similar to the "jump" we make when startled.
When we enter stage 2 sleep, our eye movements stop and our brain waves (fluctuations of electrical activity that can be measured by electrodes) become slower, with occasional bursts of rapid waves called sleep spindles (waves at 12 - 14Hz).
In stage 3, extremely slow brain waves called delta wavesbegin to appear, interspersed with smaller, faster waves.
By stage 4, the brain produces delta waves almost exclusively. It is very difficult to wake someone during stages 3 and 4, which together are called deep sleep. There is no eye movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they wake up. Some children experience bedwetting, night terrors, or sleepwalking during deep sleep.
When we switch into REM sleep, our breathing becomes more rapid, irregular, and shallow, our eyes jerk rapidly in various directions, and our limb muscles become temporarily paralyzed. Our heart rate increases, our blood pressure rises, and males develop penile erections. When people awaken during REM sleep, they often describe bizarre and illogical tales – dreams.
A complete sleep cycle takes 90 to 110 minutes on average.
The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep. As the night progresses, REM sleep periods increase in length while deep sleep decreases. By morning, people spend nearly all their sleep time in stages 1, 2, and REM.
If our REM sleep is disrupted one night, our bodies don't follow the normal sleep cycle progression the next time we doze off. Instead, we often slip directly into REM sleep and go through extended periods of REM until we "catch up" on this stage of sleep.
People awakened after sleeping more than a few minutes are usually unable to recall the last few minutes before they fell asleep. This sleep-related form of amnesia is the reason people often forget telephone calls or conversations they've had in the middle of the night. It also explains why we often do not remember our alarms ringing in the morning if we go right back to sleep after turning them off.