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Why is sleep important? The effects of sleep deprivation

People spend just under a third of their lives sleeping, and the fact that sleep is essential seems self-explanatory. Today, we’ll explain why this regenerative process is so important and what sleep deprivation does to our mind and body. You’ll learn why we sleep and how just one poor night’s sleep can affect your well-being.

by CALIDA

10 April 2024 • 6 min reading time

Man lies on his arm with his eyes closed. He is wearing a light blue sleep shirt from CALIDA.

The importance of sleep for our physical and mental health is often underestimated.

Why do we sleep and what is sleep?

When we sleep, our state of consciousness changes. We continue to breathe as our blood pressure and heart rate drop, our muscles are paralysed and we no longer interact with our environment. While some processes shut down, others use this time to work at full speed; the body regenerates from the mental and physical exertions experienced during the day.

Sleep and sleep pressure – tiredness – are controlled by hormones. The release of the sleep hormone melatonin increases when it gets dark in the evening, which is how we get tired. People with sleep disorders often have trouble falling asleep because melatonin production, which is controlled by our eyes, is not working properly.

The sleep cycle and the four sleep stages

Sleep can be divided into four stages, which reoccur several times during the night; the frequency of sleep cycles depends on the duration of sleep, which should ideally be between seven and eight hours per night.

During this time, our body releases different hormones to stimulate the regeneration of body and mind. A cycle of four stages lasts about 100 minutes and proceeds as follows:

  • Falling asleep, approximately 5%: transition between wakefulness and sleep (noises affect our sleep, we are easily startled)

  • Light sleep, approximately 50%: the body relaxes (sleep is easily disturbed, blood pressure and heart rate slow down)

  • Deep sleep, approximately 20%: body and mind regenerate (blood pressure and heart rate are low, growth hormones are released)

  • REM, approximately 25%: intense dreams and eye movements (muscles are completely relaxed, stress hormones increase)

Many people wake up after the REM stage and the sleep cycle starts all over again. Most people don’t remember this brief waking period the next morning.

Five reasons why getting enough sleep is so important

Our sleep ensures that we feel refreshed and fit. In order to achieve this, many important processes take place in the body, of which we – of course – are not aware. However, they are essential for our well-being and health. Here are the top five reasons why you should get enough sleep every day:

1. We process memories and emotions

When we sleep, we process what we’ve experienced during the day. Both good and bad memories and emotions are filtered and sorted. According to current findings, dreams may help us to contextualise our feelings and deal with them better.

That’s why adequate sleep is so essential, especially for children, who perceive the world much more intensely than adults. The new sensory impressions and situations experienced daily are processed during sleep, which contributes to cognitive and linguistic development.

2. Increased release of growth hormones

During the light and deep sleep stages, a particularly high amount of growth hormones are released; these are essential for both adolescents and adults. Tiny muscle tears and other signs of physical wear are repaired at night. Athletes in particular should therefore ensure adequate regeneration during sleep in addition to a protein-rich diet.

3. Blood pressure remains constant

During sleep, our heart rate and blood pressure drop. This is very important in order to achieve a balance between stressful periods in everyday life when our heart rate can rise. Getting enough sleep significantly reduces the risk of cardiovascular conditions such as high blood pressure.

4. Sleep strengthens the immune system

During the day, our body is busy with all kinds of tasks that prevent it from recovering or warding off illness. Information is absorbed and processed in the same way as food; we burn fat and calories, our blood pressure and insulin need to be kept in balance.

Bedtime is therefore essential in order to fight pathogens and keep us healthy. As we sleep, our immune system makes more antibodies and T cells, so-called killer cells, which destroy pathogens and maintain our health. Injuries can also heal faster if you get enough sleep.

5. Sleep stimulates the metabolism and cleanses the body

While we sleep, all metabolic processes in the body can proceed undisturbed. The metabolism of fat and glucose ensures the depletion of carbohydrate stores and a healthy insulin balance, which reduces the risk of becoming overweight and helps you lose weight more quickly. The metabolism in the brain additionally ensures that toxins are removed, meaning that your body is naturally detoxified while you sleep.

What happens if you experience acute or chronic sleep deprivation?

Sleep is essential for keeping your body and mind healthy – but what happens after you have a poor night’s sleep? Does a sleepless night actually affect your body, and what happens when we experience chronic sleep deprivation? We’ve got the answers.

Consequences of acute sleep deprivation

Everyone experiences a restless night every now and then, when they can’t sleep at all or the sleep they get is poor. Whether it’s a party, stress, racing thoughts or commitments like care work that are keeping you from sleeping, just one poor night’s sleep is enough to affect your well-being.

Many people suffer from difficulty concentrating after sleepless nights. They are slower to absorb information and their ability to express themselves also suffers. Increased irritability occurs in particular when you have to do things that you don’t feel up to doing.

In addition to a ‘shorter fuse’ and decreased memory performance, acute sleep deprivation can also have physical effects: headaches and feeling weak are typical. So it’s a good idea to take it easy on days like these and avoid activities that could be dangerous due to reduced focus. Lack of concentration and momentary nodding off can have terrible consequences, especially when driving a car!

What happens with chronic sleep deprivation

Even one night affects our brain and body, so it’s no wonder that people with chronic sleep deprivation often experience difficulties in everyday life or health problems. Among other things, persistent sleep deprivation increases the risk of:

  • Mental illnesses such as depression

  • Cardiovascular conditions such as high blood pressure

  • Metabolic diseases such as diabetes mellitus

  • Neurological diseases such as Alzheimer’s

  • Becoming overweight

  • Bacterial/viral infections

The list of possible consequences of chronic sleep deprivation is long and clearly shows how important sleep really is. You should definitely consult an expert if you suffer from long-term insomnia, since they can identify causes such as reduced melatonin production or other problems, and treat them specifically.

Our eight tips for improving your sleep

If you have trouble falling asleep or staying asleep every now and then, this is not a reason to seek medical attention. Still, you should work on your sleep in order to be fit and well rested every day. The following tips can help you improve your sleep hygiene:

  1. Have a set bedtime that suits your sleep type

  2. Practise calming evening rituals such as journalling, meditation or yoga

  3. Avoid screens, large meals, caffeine and alcohol before bedtime

  4. Use comfortable bed linen and sleepwear that’s suitable for the season and made of natural materials

  5. Ensure your bedroom temperature is between 16 and 18 degrees Celsius

  6. Ensure you’re sleeping in a tidy environment without a lot of distractions (bedroom and study should be separate)

  7. Ensure the room is completely dark and quiet

  8. Use calming, natural room scents such as lavender or chamomile

Getting enough sleep is important because it has a huge impact on our ability to function and our mood. What helps you fall asleep best?


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