We spend a staggering one third of our lives asleep. Because we are asleep, this third of our lives often passes us with little to no recognition. This strange blind spot in our own personal experience is mirrored in the scientific understanding of sleep. It is a topic that is barely taught at medical school and one that gets far less than a third of medical financial resources devoted to it. Sure we are slowly but surely piecing together the reasons for sleep but as it stands sleep is a phenomenon that is still shrouded in mystery, from the reason why we sleep through to why we dream. We really do not know as much about sleep as we would like. Let’s look at what we do know and what we don’t.
We know that sleep is as important as drinking water and eating food. How do we know that? Like food and water, going without sleep can kill you. Not indirectly, but directly. One of the earliest sleep researchers called Rechtschaffen, “experimented on rats, forcing them to stay awake. They all died of weight loss, within two weeks, despite eating more than usual.” Yes, not sleeping can actually kill you. Directly. Sleep is a key component in our lives and it is also something that we share with every other animal species from the tiny ant to the mighty elephant, we all sleep and we all need sleep to stay alive.
While we can guess at its central role in our lives, we are only just starting to understand the underlying factors that make it so important. There are massive debates and arguments raging amongst the many scientists who study sleep about why we sleep, what its primary function is. Some believe sleep has no single reason but rather a multitude of interconnected reasons, others think that we sleep to allow the body to cleanse and repair itself, another group think that sleep is a mechanistic battery recharging process while another group think that sleep developed as a way of stopping us from hurting ourselves when it was dark.
Whatever the reasons for sleep, there is one thing that all the scientists agree on. The Western world is not getting enough of it. While there is some disagreement on the exact figures, the ball park figures are that between a third and a half of all adults in the Western world are not sleeping enough. There are multiple reasons for the crisis in sleep deprivation, from the pressures and stresses of modern life through to our massive consumption of foods and drinks that play havoc with our sleep, from junk food to coffee, from alcohol to cigarettes, from our old obsession with reading books in bed to our new obsession with reading our iPad in bed, we seem to have a multitude of behaviours that are bad for our sleep.
While we still are not sure of exactly why we sleep we have started to uncover a number of the physiological and psychological functions that occur during sleep that could help us work out the ‘why’ of sleep. For example, new research has found that when we sleep the brain flushes away a range of harmful toxins that build up during the day. We have also recently discovered that sleep helps to regulate a range of hormones in the blood including some that regulate our appetite. Another group of experimenters has shown that sleep plays a major role in the memory storage process and yet another still has found that sleep is essential for cell regeneration.
When you go beyond sleep itself to the world of dreams there are even more mysteries. Dreaming is an even more confusing and even harder phenomenon to study. While sleep at least providers some physical clues to chase up, there is little that scientists can look at when they study dreams beyond the changing brain waves. What is interesting is that we do know dreams are just as important as sleep.
Before examining that a brief explanation of the different stages of sleep. There are four (or five depending on how you break them up) different stages of sleep. The most well known of these is the rapid eye movement (or REM) stages. This is the stage where we do the majority of our dreaming. We go through several REM phases during a normal night’s sleep and each of these is characterised by increased brain activity.
Right, so back to how we know that dreaming is just as important as sleep. Remember the rats who died of sleep deprivation? Well, the during the same experiment a group of rats were deprived of just their REM sleep, meaning that they were not sleep deprived but rather were woken before they entered the REM sleep stage. Guess what happened to them? Unlike those that were deprived of sleep altogether and who died in two weeks, these rats died in four. It seems that even if you sleep every night, if you are not able to enter the REM stage you may die.
These findings lead Francis Crick, who was one of the discoverers of the DNA double helix, to suggest that while non-REM sleep is for repairing the body, REM sleep is about rewiring the brain. This certainly seems like a distinct possibility but even though he came up with this hypothesis many decades ago we are still working on proving or disproving it.
So what do we know about sleep? It seems that while we are chipping away at the major questions, why do we sleep and why do we dream, we are still not 100 per cent sure of either. What we do know is that both sleeping and dreaming are not just luxuries but are vital necessities, they are both as important as the water we drink and the food we eat at helping to keep us alive and going without them will kill us just as surely as not eating or drinking would.
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