The Sleep Stages:
Since the 1950’s there has been research into sleep and brainwaves. Studies have shown that human sleep patterns progress through a series of sleep stages in which different brain wave patterns are displayed.
There are two main types of sleep:
1) Non-Rapid Eye Movement (NREM) Sleep (aka ‘quiet sleep’)
2) Rapid Eye Movement (REM) Sleep (aka ‘active sleep’ or ‘paradoxical sleep’)
In the earliest phases of sleeping, you are relatively ‘awake and alert’. The brain produces ‘Beta Waves’, which are small and fast and associated with day to day wakefulness. Beta waves are not very consistent in their patterns, which makes sense when you consider all the different inputs our brain receives while we are awake. As the brain begins to relax and slow down, slower waves, known as ‘Alpha waves’, are produced. During this time you are not quite fully asleep and you may experience vivid and strange sensations known as hypnagogic hallucinations. Examples of this would be the sensation you are falling or hear someone call your name. Another common event during this period is the ‘myoclonic jerk’, where you suddenly are startled or jerk for what seems like no apparent reason.
The 5 Sleep Stages:
1) Stage 1: is the beginning of the sleeping cycle, a relatively light sleep stage. Stage 1 is often considered the transition period between wakefulness and falling asleep. In Stage 1, the brain produces high amplitude theta waves, which are slow brain waves. This is a relatively brief period that generally lasts only 5 to 10 minutes.
2) Stage 2: is the second of the sleep stages and lasts generally about 20 minutes. The brain begins producing sleep spindles, bursts of rapid, rhythmic brain wave activity. Your heart rate begins to slow and body temperature starts to decrease.
3) Stage 3: is when deep, slow brain waves, known as delta waves, start to emerge. Stage 3 is a transitional period between light and very deep sleep.
4) Stage 4: Sometimes referred to as Delta Sleep because of the slow ‘delta’ waves occurring in the brain at this time. Stage 4 is a very deep sleep lasting approximately 30 minutes. Delta Sleep is the deepest of the sleep stages and the most difficult in which to wake a sleeper. Sleep walking, Talking in your sleep, and bed wetting are most likely to occur near the end of Stage 4.
5) Stage 5: Known as REM (Rapid Eye Movement) sleep, Stage 5 is when most dreaming occurs. REM sleeping is characterized by eye movement, increased respiration rate, and increased brain activity. REM sleep is also referred to as ‘paradoxical sleep’ because while the brain and other body systems become more active, muscles become more relaxed. Dreaming is a result of the increased brain activity, voluntary muscles become paralyzed. On average, we enter the first REM Sleep stage about 90 minutes after falling asleep. The first REM cycle may last only a short time, but each cycle becomes longer and can last up to an hour as sleep progresses.
The Sequence of Sleep Stages:
It is interesting and important to note that a sleeper does not progress through these sleep stages in sequence. Sleep does begin in Stage 1 and progresses into and through stages 2, 3, and 4. After reaching Stage 4, Stage 3 and then Stage 2 are repeated before entering Stage 5 (REM). Upon completion of Stage 5 REM sleep, the body usually returns to Stage 2. A person will cycle through these sleep stages approximately 4 or 5 times throughout the night.
To get the most effective sleeping experience, we need to be able to pass through these cycles undisturbed- thus one of the reasons it is important to have a comfortable mattress: So you can get the undisturbed stretches of rest and sleep to re-energize your body. A good night’s sleep is important for your physical and mental health.