You may find it hard to believe that up until the middle of the 20th century it was thought that our brains had an off and on switch.
Our brain would literally turn off and we’d fall asleep and then in the morning the brain would turn back on and we’d be wide awake.
If only it was that simple hey.
This almost leads me to conclude that people didn’t have problems with sleep before this, although I find that very hard to believe.
Fast forward to the modern day and age and we now understand that there is a lot more to falling asleep and waking up again.
We are now aware that sleep typically occurs in 90 minute intervals and these encompass 5 stages of sleep.
So, what are the 5 stages of sleep?
First A History Lesson
Nathaniel Kleitman, an American physiologist, wanted to know more about consciousness, but decided to base his research on the opposite end of the spectrum.
Therefore, he studied the unconsciousness that is related to sleep. His research started to unravel the many mysteries of sleep, and this is probably why he is recognized as the father of modern sleep research.
Kleitman, and one of his graduate students, Eugene Aserinsky, conducted a number of sleep experiments together. They used an early version of an EEG machine to monitor participants’ brain activity. And most famously discovered “Rapid Eye Movement” or REM sleep.
Aserinsky, noticed the wild, darting eye movements of many of the subjects on numerous occasions throughout the experiment. Kleitman, wanted to repeat the experiment, but this time on his daughter, Esther.
It was from here in 1953 that Kleitman and Aserinsky proved that REM sleep was connected to brain activity and dreaming.
And the rest, as they say, is history.
What Happens in Each Stage of Sleep?
The frequency of our brain waves play a major part in being awake and being asleep.
The more active and awake you are, the higher the frequency of the brain waves. As soon as you begin to relax, brain wave activity is far slower.
The First Stage of Sleep
The first stage of sleep, light sleep, sees muscle activity slow down, although there may be occasional muscle twitching.
Your eye movements slow right down. You may feel your muscles contract suddenly which typically gives you the sensation of falling. The first stage of sleep typically lasts about 5-10 minutes on average.
This stage of light sleep is when it is easiest to wake up
The Second Stage of Sleep
The second stage of sleep can last anywhere between 10-25 minutes and your eye movements will slow right down before eventually grinding to a complete halt. This stage is also referred to as light sleep.
Your brain waves will be very slow, although there is usually a quick surge of waves now and then as well.
These surges of waves are believed to be connected in some way to sensory processing and consolidating your memories.
Therefore, this stage of sleep is extremely important as we get older.
The Third Stage of Sleep
The third stage will see the highest magnitude of waves, although this is when your brain waves are also at their slowest.
This is when you have generally started the first of the two stages of deep sleep. Stages 3 and 4 are often combined together, which is why you may have often heard of “the 4 stages of sleep”.
The Fourth Stage of Sleep
The four stage is the deepest stage of sleep you will experience during the night. Your breathing slows right down, your blood pressure drops, your muscles relax, and human growth hormones are released, which allows the body’s cells to regenerate.
This stage is essential for your physical health and recovery. The fourth stage of sleep is what most weightlifters and bodybuilders strive for, as they know it is when their muscles will grow.
The Fifth Stage of Sleep
The fifth and final stage is REM sleep. This is identified by rapid eye movement and is most commonly associated with dreaming.
The physical effects of REM sleep include an increase in heart rate and blood pressure, and the loss of temperature regulation.
Neuroscientists are still to this day studying the full function of REM, as it is considered to be somewhat a mystery.
Nevertheless, it is accepted that REM sleep plays a pivotal role in the brain’s ability to learn and remember things. This is when the brain stores data into long-term memory.
The Facts About Sleep Stages and Cycles
- Each sleep cycle will last for approximately 90 minutes (although the time can vary, but 90 minutes is used as an average) and you will typically go through stages 1-4 the first time around. When the next sleep cycle commences stage 1 is replaced by REM sleep.
- The average length of the first sleep cycle can last anywhere from 70 to 100 minutes, whereas the second and subsequent sleep cycles will last roughly 90 to 120 minutes.
- As the night (and your sleep) progresses the length of the periods of REM sleep will increase.
- You will spend more time in the deeper sleep stages (stage 3 and 4) during your earlier sleep cycles. It is during your later sleep cycles that you spend more time in REM sleep.
- If you want to take a power nap during the day you should limit this to about 20 minutes, as you don’t want to enter the deep sleep stages. This is typically why you feel extremely groggy when you wake up after a slightly longer nap. This is commonly known as sleep inertia.
- A long nap should be for 90 minutes or more so you make it through at least one sleep cycle.
- Our sleep cycles differ with age – infants have far shorter sleep cycles and spend longer in REM sleep.
- At the opposite end of the spectrum, elderly individuals will typically experience a much longer sleep cycle, but will spend a lot less time in REM.
- For all you coffee drinkers, I’m sure you know that caffeine isn’t great for helping you sleep, and this is especially true the closer you drink a cup of coffee to bedtime. Caffeine typically has an adverse effect on your deep sleep stages during the first half of the night.
- Weirdly, it seems the opposite is true for alcohol. If you enjoy a beverage just before bedtime you’ll usually fall asleep very quickly, but later on in the evening once your body once has started to process the alcohol, it will start to act as a stimulant. This means that the second half of your night’s sleep is likely to be disturbed.
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Use The 5 Stages of Sleep to Your Advantage
The various forms of sleep deprivation are on the rise and therefore you should realize just how important sleep is for your overall physical and mental well-being.
Simply by knowing what the 5 stages of sleep are can help you to better understand your own sleep-wake cycle.
This will allow you to make any changes you deem necessary to your sleeping habits to ensure you get the perfect night’s rest.