Sleep is a mystery and still not fully understood by science, but we do know some of its common stages and how they work for us
Do you Know What Sleep Actually is?
Sleep is a natural state of altered consciousness when sensory activities and voluntary muscles are inhibited compared to wakefulness. Interactions with surroundings are also reduced to a minimum and reaction to stimuli is also decreased. In other words, we can also call it our mind’s hibernation mode. A good sleep enables the body to rest and refresh and that’s why after it, we feel nourished and fresh. Lack of sleep just like lack of food can result in many physical and psychological problems. Research has shown that even the healing process of wounds can slow down due to lack of proper sleep.
Sleep directly affects the way our body and brain functions, how we look and how we perform in our routine lives. Its lack can hinder all critical functions of our daily lives and both quality and quantity of sleep are important for a healthy lifestyle.
How much should we sleep?
On average, adults should have minimum 8 hours and on average 9.5 hours of uninterrupted quality sleep. This makes their minds and bodies rejuvenated the next morning they wake up. If the sleep time is too short, a body may not get proper time to complete all the phases necessary for muscle repair, hormone release that regulate appetite and growth and memory re consolidation. Due to lack of quality sleep, we may wake up tired, unmotivated to work and mentally unprepared for next day’s challenges and social activities.
The Sleep Cycle
Sleep consists of REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement) cycles and per sleep there are usually four cycles. The NREM consists of three sub-stages N1, N2 and N3 also called delta or slow-wave sleep. The normal procedure of sleep is N1-> N2 -> N3 -> REM.
1. NREM or Non-REM (non-rapid eye movement)
When we fall asleep out activity levels slow down and our heart rate, temperature, breathing rate and energy levels decrease. The brain waves also get bigger but slower, but we are still able to maneuver if necessary to adjust ourselves during sleep e.g. if we feel cold we can adjust our bodies. In this stage, our reflexes are fairly active and this stage of sleep constitutes about 80% of our total sleep.
a. The first sub-stage N1 consists of light and drowsy sleep when we are between sleep and wakefulness. It can also occur between deep sleep and REM. The muscles are still active and our eyes are rolling slowly and opening/closing moderately.
b. N2 constitutes about 45-55% of total sleep in adults and theta activity are observed at this stage when we slowly become hard to awake. Muscle activity decrease and we are no longer aware of our external environment.
c. N3 constitutes about 15-25% of total sleep and is also known as deep sleep. We become very less responsive to the environment and many stimuli also don't produce reactions. This stage is the most restful form of sleep and is very important as the total percentage of this stage out of our total sleep period is already low. This is also the stage mostly responsible for rejuvenating the body. This is also the stage when parasomnias like sleepwalking, nocturnal enuresis, night terrors and somniloquy occur
2. REM (Rapid Eye Movement)
REM constitutes about 20-25% of total adult sleep and in this stage most of the muscles are paralyzed, heart/breathing rate and body temperature are unregulated and we experience vivid dreams. This stage is also known as the paradoxical state when we exhibit ECG waves high in frequency similar to our awakened state but still harder to arouse us compared to any other stage. On average, an adult reached REM stage every 90 minutes and remains there for longer during latter-half of sleep. This stage comes when we return to stage 1 from a deep sleep.
Scientists don’t exactly know the function of this stage, but they do know that its lack has something to do with an inability to learn complex tasks. A newborn baby consumes 9 hours a day on average just for REM sleep and by the age of five it decreases to only 2 hours approximately.
Awakening
Awakening is the end of sleep and occurs when we start to survey our environment and start adjusting ourselves. Awakening usually happens after slow-wave sleep just after the REM stage ends and sometimes even in the middle of it. It involves brain’s rapid electrical activation starting from thalamus and further spreading throughout the cortex.
Although when we are asleep, we are far from being productive, it’s still one of the most important human needs and we should always ensure we are getting the recommended levels of sleep. This enables us to spend the remaining time being more productive and active in our lives.
Sleep is a natural state of altered consciousness when sensory activities and voluntary muscles are inhibited compared to wakefulness. Interactions with surroundings are also reduced to a minimum and reaction to stimuli is also decreased. In other words, we can also call it our mind’s hibernation mode. A good sleep enables the body to rest and refresh and that’s why after it, we feel nourished and fresh. Lack of sleep just like lack of food can result in many physical and psychological problems. Research has shown that even the healing process of wounds can slow down due to lack of proper sleep.
Sleep directly affects the way our body and brain functions, how we look and how we perform in our routine lives. Its lack can hinder all critical functions of our daily lives and both quality and quantity of sleep are important for a healthy lifestyle.
How much should we sleep?
On average, adults should have minimum 8 hours and on average 9.5 hours of uninterrupted quality sleep. This makes their minds and bodies rejuvenated the next morning they wake up. If the sleep time is too short, a body may not get proper time to complete all the phases necessary for muscle repair, hormone release that regulate appetite and growth and memory re consolidation. Due to lack of quality sleep, we may wake up tired, unmotivated to work and mentally unprepared for next day’s challenges and social activities.
The Sleep Cycle
Sleep consists of REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement) cycles and per sleep there are usually four cycles. The NREM consists of three sub-stages N1, N2 and N3 also called delta or slow-wave sleep. The normal procedure of sleep is N1-> N2 -> N3 -> REM.
1. NREM or Non-REM (non-rapid eye movement)
When we fall asleep out activity levels slow down and our heart rate, temperature, breathing rate and energy levels decrease. The brain waves also get bigger but slower, but we are still able to maneuver if necessary to adjust ourselves during sleep e.g. if we feel cold we can adjust our bodies. In this stage, our reflexes are fairly active and this stage of sleep constitutes about 80% of our total sleep.
a. The first sub-stage N1 consists of light and drowsy sleep when we are between sleep and wakefulness. It can also occur between deep sleep and REM. The muscles are still active and our eyes are rolling slowly and opening/closing moderately.
b. N2 constitutes about 45-55% of total sleep in adults and theta activity are observed at this stage when we slowly become hard to awake. Muscle activity decrease and we are no longer aware of our external environment.
c. N3 constitutes about 15-25% of total sleep and is also known as deep sleep. We become very less responsive to the environment and many stimuli also don't produce reactions. This stage is the most restful form of sleep and is very important as the total percentage of this stage out of our total sleep period is already low. This is also the stage mostly responsible for rejuvenating the body. This is also the stage when parasomnias like sleepwalking, nocturnal enuresis, night terrors and somniloquy occur
2. REM (Rapid Eye Movement)
REM constitutes about 20-25% of total adult sleep and in this stage most of the muscles are paralyzed, heart/breathing rate and body temperature are unregulated and we experience vivid dreams. This stage is also known as the paradoxical state when we exhibit ECG waves high in frequency similar to our awakened state but still harder to arouse us compared to any other stage. On average, an adult reached REM stage every 90 minutes and remains there for longer during latter-half of sleep. This stage comes when we return to stage 1 from a deep sleep.
Scientists don’t exactly know the function of this stage, but they do know that its lack has something to do with an inability to learn complex tasks. A newborn baby consumes 9 hours a day on average just for REM sleep and by the age of five it decreases to only 2 hours approximately.
Awakening
Awakening is the end of sleep and occurs when we start to survey our environment and start adjusting ourselves. Awakening usually happens after slow-wave sleep just after the REM stage ends and sometimes even in the middle of it. It involves brain’s rapid electrical activation starting from thalamus and further spreading throughout the cortex.
Although when we are asleep, we are far from being productive, it’s still one of the most important human needs and we should always ensure we are getting the recommended levels of sleep. This enables us to spend the remaining time being more productive and active in our lives.
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