Stages of Sleep
Throughout the night, we transition through a variety of sleep stages, each owning individual properties. These sleep stages have been scientifically proven from as early as the 1950's. The most prominently studied sleep stage, known as REM, was pioneered by a graduate student name Eugene Aserinsky.
There are 2 main types of sleep:
- NREM (Non-Rapid Eye Movement, also known as quiet sleep)
- REM (Rapid-Eye Movement, also known as active or paradoxical sleep)
Within the earliest phases of sleep, you're still relatively alert and most definitely conscious. The brain produces what are known as beta waves, which are small and frequent. As the brain begins to relax, you produce slower waves which are known as alpha waves. During this time you are drifting in and out of consciousness and may experience extreme sensations known as hypnagogic hallucinations. A common occurrence would be feeling as though you are falling. Stage 1
Stage 1 marks the beginning of the sleep cycle and is an extremely light version of sleep, which is often referred to as a transition between wakefulness and sleep. This period of sleep is very brief, lasting around 5-10 minutes. If you waken someone from this stage, they may report not being sleeping at all.
Stage 2
The second stage of sleep lasts for approximately 20 minutes. There are bursts of brain activity, rapid rhythmic brain waves known as sleep spindles. You will also experience physiological changes such as a drop in body temperature and a decrease in heart rate.
Stage 3
Slow, deep brainwaves known as delta waves begin to emerge during stage 3 of sleep. It can also be categorised as a transitional period between light and deep sleep.
Stage 4
Stage 4 is often referred to as major delta sleep, because of the slow brainwaves known as delta waves. This is a deep sleep state that lasts around 30 minutes. This is were bed-wetting and sleepwalking may occur.
Stage 5
Stage 5 is where most of the dreaming occurs, rapid eye movement (REM) sleep. We enter the REM stage, on average, 90 minutes after falling asleep. The first cycle of REM only lasts a short while, though each cycle increases as the night goes on. REM can last as long as 1 hour, at the later periods of the night.
