Why do we need to sleep?

Good quality sleep is crucial for health and the benefits we derive are innumerable. It is all too easy to become accustomed to a poor baseline quality of sleep in the go-go-go world we live in today to the point that we can assume this is normal. The World Health Organisation (WHO) has declared sleep loss to be an epidemic in industrialised nations. This can lead to a multitude of issues over the longer team including disease, depression, weight gain and more. The field of sleep medicine originates back to the 1970s and there is still a lot we don’t know. It’s time to demystify sleep in this primer.

What is sleep?

It’s all too easy to get caught up in the minutiae of sleep and why it is important but what is sleep? I’ve always found sleep to be intriguing and elusive. We all need sleep to survive and it certainly isn’t a period of inactivity despite the experience of absence during these hours. At its core, sleep is characterised by stereotypical body positions and a lack of responsiveness. It is a physically restful state where we are unaware of our environment and this is a state we share with many animals. In fact, even microorganisms cycle through periods of activity and inactivity thought to be controlled by their circadian clocks, which are influenced by night and day. Despite decades of sleep research, the summary is that sleep is extremely complicated and we don’t fully understand the purpose of sleep.

Lack of responsiveness occurs because our brain closes off our perception to external senses when asleep. The thalamus blocks the signals, acting as a gatekeeper to prevent these signals from reaching the higher parts of the brain (cortex).

Why we need to sleep?

There are various explanations for sleep:

  • Energy conservation
  • Emotional regulation
  • Processing information from the day
  • Consolidating our memories
We know that our heart rate slows down, and we go into a state of physical relaxation influenced by the autonomic nervous system. Studies have shown that those who experience poor sleep have increased sympathetic, and reduced parasympathetic tone. This can manifest as reduced resting heart rate and increased blood pressure. One major function of sleep may be regulation of the autonomic nervous system, often referred to as our ‘fight or flight’ response. 

Sleep in modern-day society

Humans are the only known species to deprive themselves of sleep without justifiable gain. This is exacerbated by modern day pressures to use every minute of the day to work have led to a significant shift in the way we value sleep. Now we have airports, supermarkets, cafes and more open 24/7 alongside 24/7 connectedness via our mobile phones and laptops. People have come to value productivity and connectedness to technology so much that sleep is often regarded as an interference and a waste of time. Regardless of how busy we are, the research makes it clear that we cannot afford to ignore the importance of sleep for our mental and physical wellbeing. 

Need for sleep

Pinpointing the aspects of sleep that cannot be replicated in other ways remains a great scientific challenge. We have learned much about the underlying processes that occur during sleep and how this relates to how we function during the day and our wellbeing. There is still much to learn and it is a fascinating field that I’ll be keeping my eye on.

Recommended reading ?

Why We Sleep: The New Science of Sleep and Dreams

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