Sleep is an essential part of life and vital for a normal, healthy functioning body. We are naturally programmed for quality sleep so that our bodies and minds can rejuvenate and recharge, allowing important processes to take place.
Do you know that you pass through 4 stages of sleep?
Sleep is regulated by your body (circadian) clock and consists of cycles of stages. Each stage has a particular level of consciousness and is when certain physiological processes take place. Each of these sleep cycles last from 90 to 110 minutes on average.
Stage 1 – drowsiness
Referred to as somnolence or drowsy sleep, muscle activity slows down and muscle tone becomes relaxed. There is a loss of conscious awareness of the external environment, but you can be easily awakened.
Stage 2 – light sleep
Conscious awareness of the external environment disappears. This stage occupies 45 to 55 per cent of total sleep in adults. Your heart rate slows and your body temperature decreases. This stage of the cycle is alternated throughout sleep with REM sleep.
Stage 3 – deep sleep (or slow–wave sleep characterised by delta brain waves)
At this stage it is hard to wake up, but if you do you will be groggy and disoriented. This is because blood flow to the brain decreases and redirects itself towards the muscles, restoring physical energy. Immune function increases during this cycle.
Stage 4 – rapid eye movement (REM) sleep (or dream sleep)
This stage accounts for 20 to 25 per cent of total sleep. It occurs 70 to 90 minutes into your sleep cycle and is repeated 3 to 5 times during the whole cycle. REM sleep is when you process emotions, retain memories and relieve stress. Breathing is rapid, irregular and shallow. The heart rate increases and blood pressure rises. There is complete relaxation of the muscles and vivid dreams occur just before natural awakening.
Sleep and your body
While you are sleeping specific processes occur to encourage rejuvenation and repair to take place in the following parts of the body:
While you sleep, the brain organises memories, reinforces learning by committing it to memory and improves concentration. Your moods are also regulated during REM sleep, when you are actively dreaming. The brain may also replenish dwindling energy stores that cells need to function and repair cellular damage caused by your metabolism, and may even grow new nerve cells in the brain.
The nervous system
This rests and repairs the neurons that are important for carrying out both voluntary and involuntary commands, such as breathing and the digestive process.
The immune system
Without adequate sleep your immune system is vulnerable to infections and diseases, colds and flu, and reduced tissue repair.
These are produced to trigger or regulate particular body functions and are timed for release during sleep. One of these is the growth hormone that is vital for growing children and for some restorative processes such as muscle repair. During sleep our bodies secrete hormones that help control appetite, energy metabolism and glucose processing. Loss of sleep upsets the balance. Poor sleep also increases production of cortisol, the stress hormone. Cortisol is increased just prior to waking to prepare the body for the waking day.
With sleep having such a significant role to your health, ask your self are you getting a good night’s sleep?