Understanding Sleep

Sleep is controllled by 2 processes.  The first is called the Sleep Homeostat – this controls our drive for sleep.  The longer we are awake the sleepier we become.  The more we sleep the less we require (broadly speaking of course).  Our Sleep Homeostat maintains the balance between sleep and being awake.

The second process is called the Circadian Rhythm – this controls the time of day when we sleep.  We can train our Cardian Rhythm so that we sleep at night and are awake during the day.  Just as people who work night shifts might train their Circadian Rhythm to sleep during the day and be awake during the night.

It is not really important to remember what these processes are called, just that we have them…

Sleep can be divided into two parts

• Rapid Eye Movement Sleep (REM)
• Non Rapid Eye Movement Sleep (NREM)

REM

This is the lighter stage of sleep, were we process what happened in the previous day.  This is the stage where we normally dream and is usually the time when our eyes move from side to side (hence the name). 

NREM

NREM sleep can be divided into 4 stages

Stage 1 is the falling off to sleep stage, moving from wakefulness to a very light sleep

Stage 2 is when you begin to fall into a deeper sleep

Stage 3 is a further progression into a deep sleep

Stage 4 is the deepest stage of our sleep and is when our bodies recover from the days events and our immune system builds itself.

Once stage 4 is reached the cycle reverses back through the stages and into REM sleep.  This cycle is repeated throughout the night but with more ‘deep sleep’ in the first half of the night.