What is sleep for? What if I can't sleep, how will sleep deprivation affect me? For a substantial patch of our history we have been asking, "why do we sleep?" For many of us who can't sleep and are suffering from insomnia, apnea, snoring, snoring partners, sleepless nights looking after infants and a host of other sleep problems, we know that a lack of sleep is definitely bad for you.
We don't need to be told that sleep deprivation is a form of torture.
Indeed several medical sources will tell us that sleeping is good for us, but why do we sleep? In this day and age with all our scientific advancement, how can something so vital to our functioning remain shrouded in mystery? What do we actually know about why we do sleep? REM, dreams, restless or twitching leg syndrome and all sorts of other strange things occur when we are asleep and we still have some way to go to find out exactly why and how it all fits together and how the lack of sleep really affects us.
Although we are now able to conduct studies with a more scientific approach due to the advancement of technology, even the studies we can now do, such as monitoring electric activities in the brain when we are asleep, do not give us a definitive answer.
Although our sleep can be graphed and monitored and new research is frequently presented, the exact reasoning behind why we do sleep is still debated.
Why do we sleep? We can look at three broad theories which have been put forward and tested in various studies to try to explain why we need sleep.
These theories go some way to explain the fundamental reasons of why a lack of sleep is bad for us.

• Ever drawn a blank when trying to remember something? Maybe you are sleep deprived.
  One theory of why we need sleep is information consolidation.
  Cognitive research has led to the theory that we consolidate the information we have learnt throughout the day while we sleep and are therefore better able to use our learning if we have processed the information in our sleep.
  In this way sleep is also related to our ability to memorize things.
  Studies of sleep deprivation have shown that lack of sleep causes problems with memory.
  The consolidation theory is also reinforced by studies that show that the more a species relies on learning for their behavior, for example human beings as opposed to other animals whose behavior is typically genetically determined, the more time they spend in the REM phase of sleep.
  So next time you need to study for a test or are learning something new, try to add good sleeping patterns into your routine so that your memory and learning abilities can be optimized.
  If you can't sleep and end up with sleep deprivation your memory and ability to learn will most likely be affected too.
  

• The second theory is that when we are asleep we repair and restore our bodies and minds.
  While we are sleeping our bodies increase cell repair through protein synthesis.
  REM sleep has been linked to restoring our mental functions, while NREM sleep restores our physiological processes.
  Studies have shown that during times of high physical exertion we increase our amount of REM sleep, which indicates that sleeping serves to repair and restore.
  If you are an athlete or if your fitness and health is important to you, keeping to a routine circadian rhythm is something you should be considering if you want to ensure your body gets a chance to restore and heal itself properly.
  A lack of sleep could cost you when it comes to health and athletic performance.
  

• Ever wondered why do we sleep at night and for a certain length of time? The third theory is rather interesting.
  The evolutionary theory of sleep is that we adapted periods of being active and inactive to conserve our energy.
  Species would adapt to be asleep when it is most dangerous and hence least advantageous to be awake.
  Studies of different species' waking patterns have shown that animals with a greater number of predators would typically be asleep for shorter periods of time than those with fewer predators, like a type of hibernation.
  What is interesting about this theory is that our circadian rhythm has been set by years of evolution.
  Our bodies are now programmed to sleep in a certain way and if we have a disturbed pattern resulting in periods of sleep deprivation, our body balance is disturbed and we cannot hope to function at our best.
  

It is likely that we require sleep for a number of different reasons and that we have evolved with a pattern which best suits us.
Studies have produced evidence for each of these theories and they seem to coexist quite comfortably.
While we know that when we can't sleep, the resulting sleep deprivation is bad for us, all the reasons of why we do sleep are not yet fully realized, but will no doubt lead to some interesting studies and debate in future.