The Stages of Sleep

Of all the phenomena that we experience on a daily basis, sleep is one of the least understood and most studied of all.  When you sleep, the body goes through a series of stages as it shuts down and enters a period of inactivity.  There are four primary stages of sleep, which we will discuss in detail below.  Knowing the stages of sleep will help you get a better sleep overall, and pave the way to you getting the most out of your day.

Need for sleep

Just why do we sleep anyway?  Scientists have been searching for an answer for some time, to no clear conclusion.  It’s no secret that we need it.  Prolonging the need for sleep a few hours in one night can have your body paying for it.  But why exactly do we?  There are a few different theories that scientists have put together.  One theory is that sleep is a survival mechanic that encourages us to becoming inactive at night, when survival is the most dangerous.  Another theory puts out that sleep gives the body a period of inactivity to conserve the energy that the body needs to survive.  Probably the most discussed and most likely theory is that the body uses sleep as a period to restore and rebuild.  In a sense it helps the body maintain itself through the daily grind of life.  This theory also hold the most weight, as you need less and less sleep the older you get.  Whatever the reason, we definitely need it.

Types of SleepSleep

There are two primary groups of sleep that all other stages of sleep are subgroups of.  They are NREM, or Non-rapid Eye Movement sleep, and REM, or Rapid Eye Movement sleep.  NREM sleep consists of the stages 1-4 of sleep, while REM follows the four stages.  Once REM sleep occurs, the entire cycle starts over again, beginning at stage 1 again.

Once your body begins to prepare itself for sleep, it begins producing what are called Beta Waves.  These brain waves relax the brain and begin slowing down bodily funtions.  Once the brain and body begin to slow down, the brain begins producing Alpha Waves, which are slower than Beta Waves.

Once your body begins producing Alpha waves, the brain moves into Stage 1 of sleep.  Stage 1 is an extremely light stage of sleep, and one can be woken easily.  Stage 1 is characterized by the production of Theta Waves.  As this stage is more of a transitional stage between wakefulness and sleep, most people won’t even perceive it as being asleep.  This stage typically lasts from five to ten minutes.  This is the best stage of sleep to wake up during.  Waking up during this stage of sleep will feel natural, and allow you get get up and go about your day easily.

Stage 2 lasts for around twenty minutes, and is characterized by the brain’s production of sleep spindles.  Sleep spindles are rapid, sudden, and rhythmic bursts of brain waves.  As these sleep spindles are created, the heart rate begins to slow and body temperature begins lowering.

Stage 3 is characterized by the production of delta waves.  Delta waves are the slowest of the brain waves produced during sleep.  During the stage the individual finally begins to reach a state of deep sleep.  Environmental stimuli will often fail to generate a response, and if the person is woken up, they will experience a state of discomfort and confusion.

The fourth and final stage of sleep is known as Stage 4.  During this stage, the body transitions into REM sleep.  During REM sleep, the muscles of the body become increasingly relaxed, while the brain becomes more active than ever.  This phenomenon is referred to as paradoxical sleep.  Because of the increased brain activity during this stage, dreaming usually occurs.  Because stage 4 is the heaviest stage of sleep, it is by far the worst stage to wake up during.  Waking up during stage 4 will result in heavy grogginess and a lack of energy.

After REM sleep occurs, the body reverts itself back to stage 1 and goes through the cycle again.  This process is known as the sleep cycle.  Throughout the night the body goes through periods of NREM and REM multiple times.  This is normal and is necessary for a healthy sleep.