Are you getting enough

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Professor Jim Horne of Loughborough University recently addressed the Oxford University Scientific Society with the question: "Why Sleep?" A room full of bright, talented Oxford students suddenly looked remarkably blank. It may have been the fact that the lecture was held at 8:30pm and so, somewhat ironically, many of those present were already droopy-eyed before the talk even began. Still, probe the minds of Oxford students, or anyone in the general public, and the overall perception of sleep appears extremely limited. Preconceptions are replete with inaccuracies, assumptions and mythology. Sleep is a phenomenon that pervades our everyday lives, altering the way we act, the way we speak and the way we feel. Yet even science is at a loss to explain its intricacies. So how does sleep work? Why do we do it? How much are Oxford students getting? And, more importantly, are we getting enough?In order to get some answers rofessor Jim Horne of Loughborough University recently addressed the Oxford University Scientific Society with the question: "Why Sleep?" A room full of bright, talented Oxford students suddenly looked remarkably blank. It may have been the fact that the lecture was held at 8:30pm and so, somewhat ironically, many of those present were already droopy-eyed before the talk even began. Still, probe the minds of Oxford students, or anyone in the general public, and the overall perception of sleep appears extremely limited. Preconceptions are replete with inaccuracies, assumptions and mythology. Sleep is a phenomenon that pervades our everyday lives, altering the way we act, the way we speak and the way we feel. Yet even science is at a loss to explain its intricacies. So how does sleep work? Why do we do it? How much are Oxford students getting? And, more importantly, are we getting enough?PIn order to get some answers I performed some basic field research on undergraduates. The survey was a simple set of questions designed to see how much sleep students get during term time. The first and most striking discovery from the data was the response to the question about how much sleep students would ideally have. Of the 78 people that took part in the survey, almost 27% stated they would prefer to have ten or more hours in bed if they had the time, with 4% saying they would like to sleep for 12 hours or more on a regular basis! Most people say that sleeping longer means you are more rested and mentally sharp when you wake. But is this really the case?Sleeping is split into two defined phases that cycle throughout the night. First there is the deeper sleep known as non-ReM. This is divided into three stages, the first of which involves a very light sleep that only lasts about ten minutes. The body then enters true sleep, a deeper unconsciousness where the heart rate drops and the breathing pattern slows. This stage makes up the majority of our time sleeping. Twenty minutes later the body enters deep sleep, when breathing and heart rates reach their lowest level of the night. Critically, brain functions are also affected. When we are awake the delta waves which signal brain activity typically have very high frequency and a low amplitude. The high frequency of the signals means that the ‘refresh rate’ of our consciousness is greater during the day. during deep sleep these turn into slow, large-crested waves. Within 90 minutes of falling asleep, the second phase is initiated: ReM, or Rapid eye Movement sleep. The delta waves are extremely similar to those of someone who is awake; in fact their frequency can even exceed that of a fully conscious individual. Blood pressure rises, the breathing rate increases and as the name suggests our eyes dart wildly from side to side. Hence, ReM is characterised by very shallow sleep and it is during this period that most dreams occur. despite the intensity of brain activity at this stage, the body is effectively paralysed and so the individual is prevented from acting out their dreams. This cycle replays itself throughout the night, until we wake.It is also worth considering the difference between sleep and resting. Very little energy is conserved by sleeping. In fact, the amount saved each day by sleeping for eight hours is a mere 50kCal, about the equivalent of a piece of toast. Resting is a chance for the body to recuperate resources, repair tissues and redistribute supplies around the body. This can be done by simply reducing the level of activity for a period of time, rather than by sleeping. Sleep has a much larger effect on the brain than on the rest of the body.Individuals suffering from sleep deprivation typically suffer from grogginess, irritation and forgetfulness. Their ability to hold articulate conversations also suffers, as does their attention span and levels of concentration. The decrease in mental agility observed in a person going 17 hours without sleep is equivalent to that after two glasses of wine, the legal drink driving limit in the UK. However studies show that if subjects are kept awake for a few days without sleep, though they exhibit many of the neurological symptoms described above, there is no effect on the body at all. Contrary to popular belief even the immune system functions normally. Only the stress of not sleeping, rather than the lack of sleep itself, causes immune suppression. Hence, whilst rest aids the replenishment of the body, sleep aids the recovery of the mind, and the two concepts are entirely separate.According to the findings of the survey, students in Oxford tend to go to bed late and get up relatively early. The former (with 93.6% of those sampled still up and about after midnight) comes as no surprise, and only reflects the late-night culture of students. More surprisingly though was the finding that only 20.5% were still in bed after 9am. However, though there is a tendency to give ourselves a pat on the back for not conforming to the typical student stereotype, the survey does reveal that we are getting, on average, only around 7.5 hours sleep per night – over an hour less than we would like. Though the survey’s sample size is relatively small, it still shows that there is a discrepancy between how much sleep we want and how much we are getting.Furthermore just over 55% of students asked reported suffering from insomnia at least once a month. eating late at night, drinking alcohol, caffeine and smoking all have a detrimental effect on our sleep, as do noisy neighbours or housemates. However, the most significant causes of insomnia are psychological: grief and stress can lead to an over-stimulated mind and an inability to fall asleep. These cerebral factors are likely to be most influential in a university environment such as ours. Sleeping difficulties affect around 25% of the overall population, so such an incidence of insomnia here in Oxford should probably be expected. Still, it is worrying to see a large difference between students and the wider public, especially when the longer term physiological impacts of sleep loss are not fully understood.A less severe, but certainly more common occurrence is the effect of alcohol on sleeping patterns. Alcohol disrupts the intricate cycling of the sleeping stages. Going to sleep drunk means you are less likely to enter the deep sleep stage, instead flitting around in ReM sleep for most of the night. during the second half of the night you will sleep fitfully, awaking abruptly and struggling to regain deeper sleep. Though this may not manifest itself in actual consciousness, the depth of sleeping is invariably shallower as a result.So why do we sleep? Why does the body and mind shut down if the energy savings by doing so are only equivalent to tomorrow’s breakfast? due to the imprecise nature of the science there are many theories being thrown around. The famous suggestion by Francis Crick was that the purpose of sleep is to allow the brain to "take out the trash," for the brain to deprogramme the events it does not wish to store in the long term memory. Though this may not be physiologically accurate, the purpose of sleep does appear to be entirely based on the recalibration of the cerebral cortex. The sheer quantity of information absorbed after 16 or so hours of consciousness is staggering, the brain has been rewired extensively. Sleep may be a simple way for the brain to calm its activity and to decipher its position in the context of the world; in essence, to reaffirm its identity. It is the reordering of the brain’s synaptic superstructure thatthat seems to be the most pivotal aspect of sleeping.Finally: how much sleep do we need? Napoleon, who was not a good sleeper, once declared: "six hours sleep for a man, seven for a woman and eight for a fool." Given that the cycling of the deep sleep stage ends after around four hours, then the need for twelve or more hours of sleep per day comes across as questionable. Professor Jim Horne himself concluded that six hours of quality sleep should be enough for most of us. A surprising response perhaps, and one which according to our survey is only shared by 20% of students. Perhaps though our desire for a long lie-in has more to do with avoiding that impending essay than recovering from yesterday’s exploits.ARCHIVE: 5th week MT 2005

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