12th March 2018
It’s believed humans spend around a third of their lives sleeping, but have you ever wondered why we sleep in the first place?
If you think about it, we spend a good portion of our day in a vulnerable, unconscious and paralysed state. Although times have changed since the dawn of mankind, many of us now sleep in the comfort of our homes, without the risk of getting attacked by animals in the night as our ancestors once faced.
Researchers believe the longest we could go without sleep is around 11 days, this would result in significant deficits in concentration, motivation, perception and other mental and physical processes. It’s obvious we need sleep, however why we sleep is a popular conundrum, as although many have researched the area it would be fair to say we don’t have a definitive answer as to why we sleep.
What we can be sure about is that sleep if very important for our health and well-being, in short it enables our brains and bodies to recover. Sleep scientist Allan Rechtschaffen conducted an experiment on sleep depriving rats, which resulted in them dying within two/three weeks. The experiment of course can’t be carried out on humans for obvious reasons, but it does show the importance of sleep.
There are 5 defined stages of sleep, the first four stages are non REM sleep and the final stage is REM sleep.
The first stage is the light sleep period in which you can be woken up easily. Within minutes of falling asleep the brain starts to produce alpha and theta waves and the eye movement slows down. This stage is usually brief lasting around 7 minutes or longer if you are disturbed, as you are still somewhat alert in this stage.
During stage two you are still in a fairly light sleep, however this is when the body starts to prepare for a deep sleep. The brain produces sudden increases in brain wave frequency known as sleep spindles and the body temperature begins to drop and the heart rate slows. If you are having a ‘power nap’ you would want to wake up after this stage.
Stages 3 & 4 are often referred to as ‘slow wave sleep’, the process of going into deep sleep. During this stage the brain begins to produce slower delta waves and you won’t experience any muscle activity or eye movement. At this stage it becomes harder for you to be woken up as your body becomes less responsive to outside stimulants, if you were to wake up it is likely you would feel disorientated for a few minutes. During this stage the body regrows tissues, builds muscle/bone and strengthens the immune system. Unfortunately the older you get the less deep sleep you achieve; therefore you need to get as much sleep as you can while you are younger.
REM sleep usually happens around 90 minutes after you fall asleep. The first stage of REM lasts around 10 minutes, with the later stages taking longer, an average adult can have five to six REM cycles each night. The final stage can last up to an hour and it’s in this stage when the brain becomes more active. Your eyes jerk quickly in different directions and your heart and breathing quickens. It’s during this stage that you can experience intense dreams. Adults spend around 20% in the REM stage, whereas babies can spend up to 50%.
The different phases last for different durations at various stages of our lives, therefore on an average night you move through the stages in a sequential manor.
Working out how much sleep you need is based on a number of personal factors; therefore there isn’t a definitive number. It’s all about the quality of your sleep not necessarily the quantity, therefore it’s important to listen to your body to see if you feel refreshed when you wake. Over time you can then work out what the factors/times are when you feel most refreshed in the morning and incorporate this into your nightly routine.
Having said that the Sleep Council have put together some guidelines on the recommended hours of sleep required per age, please see table below for more details
Everyone from time to time will experience a poor night’s sleep, leaving you feeling fatigued, short tempered and lacking concentration. Although you may feel irritable this wouldn’t have any harming effect on your health. However if you experience several sleepless nights this can start to affect your health. Your brain will start to fog resulting in the difficulty to concentrate and make decisions. Your likelihood of injury/accidents increases and you may also start to feel down and even fall asleep in the day.
If this condition was to continue it can make you more prone to more serious medical conditions such as high blood pressure, heart disease, obesity and diabetes. This is why it’s very important to get a good night’s sleep, if you are experiencing issues it would always be advised to contact a medical practitioner.
Research has taken place that suggests sleeping less may result in an increase in weight. The study found that people who sleep less than seven hours a day tend to gain more weight and have a higher risk of becoming obese. If you are sleep deprived you have reduced levels of leptin, this is the chemical that makes you feel full and increased levels of ghrelin, a hunger stimulating hormone.
If you usually sleep for less than five hours a night, you have an increased risk of developing diabetes, according to a medical study. The study suggests that missing out on deep sleep may lead to type 2 diabetes by changing the way the body processes glucose (the high energy carbohydrate that cells use for fuel).
Some of us are more prone to catching every cold and bug going around, have you ever thought that could be a result of poor sleep? Prolonged sleep can disrupt your immune system, therefore meaning you are less able to fend off any nasty bugs that could make you ill.
Most of us have woken up in an irritable mood after a poor night’s sleep, have you ever wondered how this could affect your health if you suffer from sleep deprivation for prolonged periods of time? Chronic sleep debt can result in long term mood disorders such as anxiety and depression.
Sleep deprivation is believed to be a contributing factor for difficulty conceiving for both men and women. Disruptions to sleep reduce the secretion of reproductive hormones, therefore causing potential difficulties conceiving.
It is believed long-standing sleep deprivation is associated with increased heart rate & blood pressure and increases in chemicals linked with inflammation, all of which can put extra strain on your heart.
Although there isn’t a concrete answer as to why we sleep, what is certain is the importance of a good night’s sleep for our health and well-being.