One of the most enthralling studies within the fields of psychology and neuroscience revolve around a conventional activity we all perform with every day that passes by: Sleep.

When our eye lids are fastened and reality is no more, sleep may not appear to be as any extraordinary process but in fact, it uncovers a great deal about the way in which the human brain functions. Cognitive psychologists and neuroscientists have not only revealed innumerable reasons to why we sleep and dream, but have also thoroughly scrutinized the cycles that occur in the process. Our desire to have a siesta is prompted by natural cycles of activity in the brain. Altogether, Sleeping constitutes of two main states, REM (Rapid eye movement) and NREM (non-Rapid eye movement). Typically, we all begin with the NREM cycle that is to be followed by a short period of REM whilst the overall percentage of each varies as we age.

But before that, there is the bewitching state that we all go through known as the hypnagogic state. We’ve all experienced this peculiar phenomenon at the very initial stages of our sleep, where we witness familiar faces, landscapes and geometric shapes behind our closed eyelids. As all these characteristics blend with another along with the thoughts we were having whilst wakefulness as reality gradually fades away.

The NREM cycle generally consists of four stages. The first stage is the stage of dozing of into sleep itself. It is the varying activity in the brain, as our eyelids get heavy and eventually shut. One can be effortlessly brought back to wakefulness especially by ones own thoughts. Nevertheless, being aroused from this stage of sleep can make on feel as if one hasn’t slept at all. What makes this stage quite fascinating is that it is within this stage that most of us experience the most common ‘dream’ of falling which in return results into sudden muscle contractions (Called Hypic myclonia).

The second stage includes a period of light sleep. As we get older this stage tends to lengthen and we sleep more lightly. Nevertheless, the purpose of this stage is to prepare the body for deep sleep. Polysomnographic readings indicate spontaneous periods of muscle contractions and relaxations as the heart rate slows down and body temperature increases until the body reaches the final stages.

The third and fourth stage both include deep sleep where the fourth one is considerably more intense than the third. Ever been aroused after a fair amount of sleep to feel severely languorous?  That’s because it doesn’t matter how many hours of sleep you get, as long as you are woken up in any of these two stages, you will feel quite disembodied for at least a few minutes.

The NREM sleep has proven to be quite a significant cycle as it repairs and regenerates tissues, builds new bones and muscles and strengthens the immune system.

Moreover, it is followed by the REM (Rapid Eye Movement) cycle that generally occurs ninety minutes after sleep onset. The recurring cycles lengthen throughout ones sleep with the first being around 5 minutes and the final one being around an hour. Throughout the cycle, heart rates and respiration rates speed up and eyes move rapidly in all directions (hence the name). It is within this stage that we all undergo intense dreams as a result of heightened brain activity. Whilst we dream, major voluntary muscles in our body are paralyzed in order to prevent us from acting out our dream.

But the mind-blowing part is this; polysomnograms show brain wave patterns in REM to be similar to that of wakefulness. In other terms, we are wide-awake but in a contrasting state of consciousness. So every time you go to sleep, you are actually wide-awake within your own head during the REM cycle but are aroused to not remember anything! So how can we be so sure that we’re not dreaming now?