Work hard, sleep hard
Written by Jann Yee Chin
As a medical student, there have been many times when I wished sleep was unnecessary: the desperate moments cramming, hoping it will be enough for the exam the next morning. Yet each hopeless attempt ends in a cowardly retreat to bed, overpowered by that desire to sleep. We find ourselves increasingly burdened by the need to balance a successful career and secure finances against social and family lives. The frequent outcome — sleep deprivation — impairs our efficiency and causes mental and physical disorders. Whether sleep deprivation is a global problem or not has become a hot topic of debate.
Sleep is vital to all mental and physical human activities, and so it is recommended that we have 7–9 hours of it a night in order to guarantee our good health, safety and optimal performance. The UK has little representative data on sleeping patterns in comparison to the US. However, in 2004 the Surrey Sleep Research Centre carried out a cross-sectional survey. Through face-to-face interviews of 2,000 British adults, aged 16–93 and randomly selected at national sampling points, 59% reported sleeping problems in the previous week, with 18% admitting that they do not sleep sufficiently on the majority of nights. The youngest participants, aged 16–24, slept one hour longer than the average of 7 hours calculated from the entire sample. There was no discernible difference between men and women.
These findings correlate well with the US studies, but in comparison with 40-year-old data reveal no statistically reliable reductions. Nevertheless, the concern surrounding sleep deprivation stems from laboratory studies that suggest that even relatively moderate restrictions on sleep can lead to decreased performance and health. Epidemiological studies have reported associations between sleep and mortality, work safety, and mental and physical health.
Sleep deprivation leads to a number of physiological changes, of which two have been identified as the most important. Researchers from the University of Tennessee showed that sleep-deprived rats become immunocompromised and die primarily of bacterial infection, while a group at the University of Lübeck in Germany saw a similar immunosuppression in humans, with sleep-deprived individuals producing fewer antibodies to vaccinations. The second important change relates to the maintenance of the neural system and the consolidation of memory. Hallucinations, mood swings and mental illness may develop with prolonged sleep deprivation. The majority of sleep deficit effects are thought to be due to dysfunction of the brain’s frontal cortex, which is responsible for cognitive control, orchestrating thoughts with actions, maintaining attention, emotional control, and learning from experience and mistakes. Scientists from the University of Athens studied 22 patients with obstructive sleep apnoea syndrome, a respiratory disease that causes sleep deficiency. Using Magnetic Resonance Spectroscopy, they observed a significant decrease in the activity of the frontal cortex in comparison to healthy individuals. They concluded that less sleep allows less time for the nerve cells to rest and repair, and this results in neural damage by excess metabolic end-products and frontal cortex dysfunction.
There are two processes that control sleep. The first is a biological clock located in a region of the brain called the suprachiasmatic nucleus, which responds to light and controls the timing of sleep, so that we are more active in the daytime and asleep at night. It also controls processes vital for growth and development. Sleep is divided into five stages — a ‘rapid eye movement’ (REM) stage and four stages of non-REM. These stages cycle throughout the night, alternating between non-REM and REM sleep every 90 minutes. The second process relates to the specific neural control of REM and non-REM sleep. The multiple components of REM sleep suggest the interaction of multiple cellular pathways. Researchers confirmed this in 1975, showing two groups of neurons, one controlling the onset of REM sleep, and the other, its offset. The onset is driven by neurons producing the neurotransmitter acetylcholine (called cholinergic neurons), whilst the offset is determined by a different type of neurons, which produce 'aminergic' neurotransmitters and have an inhibitory effect upon the cholinergic cells. The neural activities of both are reciprocally related by a negative feedback loop.
Consistent with the fact that dream sleep is emotionally charged, brain imaging studies indicate that an ‘arousal pathway’ stimulates the hypothalamus and a part of the brain known as the limbic system. Accumulated evidence has shown that non-REM sleep is caused by the inhibition of the pathways that produce this stimulation. In a series of experiments in the 1970s, scientists showed that non-REM sleep resulted in a reduced activity pattern of cells belonging to the reticular activating system (RAS). The RAS involves the basal forebrain area, which sends cholinergic neurons to the frontal cortex.
There has been much interest in the chemicals that can induce sleep. Researchers explored the release of such chemicals, and discovered that the neurons at the base of the forebrain possess receptors for adenosine, an important metabolic chemical. They isolated a class of receptors that, upon binding of adenosine, causes an efflux of positively charged potassium ions. The resulting internal negative charges of the neurons cause reduced cellular activity. Thus, a negative feedback system exists to dampen arousal with increasing stimulation, which explains why over longer periods of being awake, we become increasingly tired.
There has been an equal amount of interest in discovering substances that could bypass altogether the need for sleep. The potentially improved efficiency could open up a world like the one represented in the television drama series 24. Alternatively, we could spread our current physiological workload over a longer time period, which would allow for the social activities we so desire. Caffeine is widely consumed to counter fatigue, to good effect. Its primary mechanism of action is to compete with adenosine at the receptors found in the RAS. The stimulant effects on mood, attention and performance are largely recognised, and extensive research by food and drug associations have shown it to be a safe drug with no health risks. Yet the use of caffeine as a counter-measure is not universally supported. Caffeine delays tiredness but does not inhibit the side-effects of sleep deprivation.
Altering our lifestyles and working habits to ensure healthier living is clearly more beneficial than relying on counter-measures against sleep deprivation. Despite my occasional desperate efforts to stay awake, I welcome the bliss of sleep and leave a world without it for someone else’s dreams.
Jann Yee Chin is a medical student based in Addenbrookes Hospital
As a medical student, there have been many times when I wished sleep was unnecessary: the desperate moments cramming, hoping it will be enough for the exam the next morning. Yet each hopeless attempt ends in a cowardly retreat to bed, overpowered by that desire to sleep. We find ourselves increasingly burdened by the need to balance a successful career and secure finances against social and family lives. The frequent outcome — sleep deprivation — impairs our efficiency and causes mental and physical disorders. Whether sleep deprivation is a global problem or not has become a hot topic of debate.
Sleep is vital to all mental and physical human activities, and so it is recommended that we have 7–9 hours of it a night in order to guarantee our good health, safety and optimal performance. The UK has little representative data on sleeping patterns in comparison to the US. However, in 2004 the Surrey Sleep Research Centre carried out a cross-sectional survey. Through face-to-face interviews of 2,000 British adults, aged 16–93 and randomly selected at national sampling points, 59% reported sleeping problems in the previous week, with 18% admitting that they do not sleep sufficiently on the majority of nights. The youngest participants, aged 16–24, slept one hour longer than the average of 7 hours calculated from the entire sample. There was no discernible difference between men and women.
These findings correlate well with the US studies, but in comparison with 40-year-old data reveal no statistically reliable reductions. Nevertheless, the concern surrounding sleep deprivation stems from laboratory studies that suggest that even relatively moderate restrictions on sleep can lead to decreased performance and health. Epidemiological studies have reported associations between sleep and mortality, work safety, and mental and physical health.
Sleep deprivation leads to a number of physiological changes, of which two have been identified as the most important. Researchers from the University of Tennessee showed that sleep-deprived rats become immunocompromised and die primarily of bacterial infection, while a group at the University of Lübeck in Germany saw a similar immunosuppression in humans, with sleep-deprived individuals producing fewer antibodies to vaccinations. The second important change relates to the maintenance of the neural system and the consolidation of memory. Hallucinations, mood swings and mental illness may develop with prolonged sleep deprivation. The majority of sleep deficit effects are thought to be due to dysfunction of the brain’s frontal cortex, which is responsible for cognitive control, orchestrating thoughts with actions, maintaining attention, emotional control, and learning from experience and mistakes. Scientists from the University of Athens studied 22 patients with obstructive sleep apnoea syndrome, a respiratory disease that causes sleep deficiency. Using Magnetic Resonance Spectroscopy, they observed a significant decrease in the activity of the frontal cortex in comparison to healthy individuals. They concluded that less sleep allows less time for the nerve cells to rest and repair, and this results in neural damage by excess metabolic end-products and frontal cortex dysfunction.
There are two processes that control sleep. The first is a biological clock located in a region of the brain called the suprachiasmatic nucleus, which responds to light and controls the timing of sleep, so that we are more active in the daytime and asleep at night. It also controls processes vital for growth and development. Sleep is divided into five stages — a ‘rapid eye movement’ (REM) stage and four stages of non-REM. These stages cycle throughout the night, alternating between non-REM and REM sleep every 90 minutes. The second process relates to the specific neural control of REM and non-REM sleep. The multiple components of REM sleep suggest the interaction of multiple cellular pathways. Researchers confirmed this in 1975, showing two groups of neurons, one controlling the onset of REM sleep, and the other, its offset. The onset is driven by neurons producing the neurotransmitter acetylcholine (called cholinergic neurons), whilst the offset is determined by a different type of neurons, which produce 'aminergic' neurotransmitters and have an inhibitory effect upon the cholinergic cells. The neural activities of both are reciprocally related by a negative feedback loop.
Consistent with the fact that dream sleep is emotionally charged, brain imaging studies indicate that an ‘arousal pathway’ stimulates the hypothalamus and a part of the brain known as the limbic system. Accumulated evidence has shown that non-REM sleep is caused by the inhibition of the pathways that produce this stimulation. In a series of experiments in the 1970s, scientists showed that non-REM sleep resulted in a reduced activity pattern of cells belonging to the reticular activating system (RAS). The RAS involves the basal forebrain area, which sends cholinergic neurons to the frontal cortex.
There has been much interest in the chemicals that can induce sleep. Researchers explored the release of such chemicals, and discovered that the neurons at the base of the forebrain possess receptors for adenosine, an important metabolic chemical. They isolated a class of receptors that, upon binding of adenosine, causes an efflux of positively charged potassium ions. The resulting internal negative charges of the neurons cause reduced cellular activity. Thus, a negative feedback system exists to dampen arousal with increasing stimulation, which explains why over longer periods of being awake, we become increasingly tired.
There has been an equal amount of interest in discovering substances that could bypass altogether the need for sleep. The potentially improved efficiency could open up a world like the one represented in the television drama series 24. Alternatively, we could spread our current physiological workload over a longer time period, which would allow for the social activities we so desire. Caffeine is widely consumed to counter fatigue, to good effect. Its primary mechanism of action is to compete with adenosine at the receptors found in the RAS. The stimulant effects on mood, attention and performance are largely recognised, and extensive research by food and drug associations have shown it to be a safe drug with no health risks. Yet the use of caffeine as a counter-measure is not universally supported. Caffeine delays tiredness but does not inhibit the side-effects of sleep deprivation.
Altering our lifestyles and working habits to ensure healthier living is clearly more beneficial than relying on counter-measures against sleep deprivation. Despite my occasional desperate efforts to stay awake, I welcome the bliss of sleep and leave a world without it for someone else’s dreams.
Jann Yee Chin is a medical student based in Addenbrookes Hospital
posted by Eau at 5:17 pm
2 Comments:
This post is interesting.. Hmmm... Though my professors at med always say that 7 hours sleep is way too much for a medical student. Haha.. I don't know.. My professor also said, as long as the sleep including REM phase enough, even if the person sleep very little, it'd be enough. Good blog!
well, how do you know if you sleep through the REM phase enough if you don't sleep enough in the first place? 8 hours ensure this, I think.
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