Deadlines and exams often tempt us to maximise our time by pulling all-nighters, but Emily Longworth explains why this is a counter-intuitive methodEven the most sane and responsible among us have pulled an all-nighter during the college term. With the accumulative stress of mid-terms and exam times peaking more than once throughout the year, it often seems like a better option to deprive yourself of sleep for the sake of a few more hours’ cramming. Anyone can assess that this is a bad tactic, as all humans are partial enough to sleep to dedicate a third of their lives to it, but somehow the world of science still hasn’t pinpointed what exactly sleep does.It is also still under discussion as to what the effects are of getting little sleep regularly; are they as damaging of one night of getting no sleep at all? Most studies deal with both separately, as each have uniquely complex effects on the body and mind. An all-nighter is defined as an incidence of acute total sleep deprivation (essentially, going straight into college after powering-through a night of partying and/or cramming). But regular sleep loss is termed chronic partial sleep restriction, which is inarguably more common amongst students. The effects of the all-nighter are more extensively researched, but both models of exam-time sleep for students have their detrimental side-effects.Despite the unanswered questions surrounding the exact function of sleep, we do know that it’s vital to body restitution, in the same way that energy conservation, thermoregulation and tissue recovery are. It’s essential to cognitive performance too; this is especially relevant to memory conservation. These effects just haven’t been directly seen under a microscope, the study of memory in itself is a multi-layered field with many inconclusive theories still. So how does sleep directly affect memory?"Memory recall and ability to maintain concentration are much improved when an individual is rested," says Dr. Philip Alapat, medical director at the Harris Health Sleep Disorders Center in the US. But the technicalities of why are only partially explained. Sleep loss does activate the sympathetic nervous system, one of the main parts of our body’s autonomic nervous systems which generally functions to maintain the body’s fight-or-flight response.When the normal function of the sympathetic nervous system is interrupted by sleep deprivation, blood pressure rises and stress increases. This is owing to cortisol (the “stress hormone”) which is released when we haven’t slept. Cortisol has an intrinsic effect on our stress levels, and our continued health. One study showed that in people who had repeatedly gotten less sleep than the prescribed 8-hours, having undergone 6 days of restricted sleep, the cortisol concentrations in their bodies were 6 times higher than those who were well-rested. This shows that even getting a poor sleep on a regular basis will mitigate the body’s stress balance.In sleep deprivation, increased cortisol levels are one of the bigger parts of our understanding of insomnia. The less we restore cortisol levels to what they should be, the more likely it is we’ll be unable to sleep again, as our internal hormonal rhythm is wholly disturbed. Mood alterations and insomnia are said to be directly caused by repeated disruption to our cortisol levels. Essentially, even if you pull an all-nighter and somehow battle to stay awake through the entirety of the next day, you still may not feel tired come nightfall. This is the curse of the insomniac.Aside from this, sleep loss and sleep deprivation can cause weight gain, both long-and short term. One function of cortisol is to release glucose into the blood system when blood sugar gets too low. When cortisol is too high, unnecessary glucose is released and cannot be burned up, ultimately being stored as fat. Where another study concluded that: “Elevations of evening cortisol levels in chronic sleep loss are likely to promote the development of insulin resistance, a risk factor for obesity and diabetes.” The body’s immediate and accumulative response to sleep loss is conducive to putting on weight.But the most immediately noticeable and enduring part of an all-nighter is the inability to concentrate. According to the US National Library of Medicine and National Institute of Health, sleep deprivation affects the brain’s frontal lobes, which in turn slows down their communication. Essentially, this is the impairment of special, auditory and visual attention, which equates to feeling like the living dead for a 9am lecture.If our overall vigilance is so highly impaired, and our performance in more demanding cognitive functions is lacking after a night of no sleep, surely there’s not a good word to be said for pulling an all-nighter right before an exam. But somehow, we still do it, probably because it feels like it maximises our time. But all sleep researchers have stated that the opposite is true – in stressing our neuron function and pushing the brain to its limits. In fact, it was found that polyphasic sleep, the gain of at least a few hours sleep, sporadically and unstructured, is better than no sleep at all.Additionally, there is evidence that shows how our working memory is significantly impaired by sleep deprivation, as well as our ability to multi-task or recognise faces. When all of this is put together, despite the lack of conclusive agreement over how exactly sleep keeps our body’s ticking among scientists, it still doesn’t seem to make sense to pull an all-nighter. Where all known disadvantages significantly outweigh the advantages of no sleep, we can agree that putting the books away and replacing them with snores is the wise student’s choice.