The Importance of Sleep
SLEEP WELL – FOR THE
REST OF YOUR LIFE!
Sleep is essential for all of us; yet a huge number of us have problems in regularly getting a good night’s sleep. So the more we know about it the better.
Why is sleep important?
Sleep is a necessary biological function to keep us physically and emotionally well. A good night’s sleep is restorative and refreshing, and helps with the ability to function well the next day by enabling the body and brain to be rested, reorganised and rejuvenated. Studies show that how well we sleep in the night is directly linked to next-day productivity and wellbeing.
How does sleep happen?
Humans have an internal 24-hour biological clock called the circadian rhythm, which governs the sleep/wake cycle, telling us when to sleep and when to wake. The circadian rhythm acts as the body’s natural internal time keeping system and is synchronised to the dark-light cycle where we live.
What happens when we sleep?
Normal sleep is made up of five different stages that form the sleep cycle. Stages 1 to 4 are part of non-rapid eye movement (NREM) sleep, and Stage 5 is called rapid eye movement (REM) sleep. We go through the sleep cycle several times a night.
• Stage 1: light sleep - the transition from wakefulness to sleep
• Stage 2: the onset of sleep - disengagement from surroundings
• Stage 3: deep sleep begins - the first restorative phase of sleep
• Stage 4: further deep sleep – waking from this stage becomes more difficult. This deep sleep helps the body repair itself and replenish energy levels
• Stage 5: REM sleep - usually begins about 90 minutes after onset of sleep. Each period of REM sleep gets longer throughout each sleep cycle. REM sleep is essential for maintaining alertness and functioning in the day
How much sleep is needed?
Different people need different amounts of sleep. For some, only three hours a night may be enough, but most of us will need about seven to eight hours a night to feel refreshed the next day.
What is the effect of age on sleep?
Generally, as we get older it is normal for sleep patterns to change and this can be due to alterations in the sleep cycle, which occur naturally with age. Young and middle-aged adults typically complain of difficulty falling asleep. Elderly people more often experience nocturnal awakening and early morning awakening. The prevalence of insomnia also increases with age.
Is the quality of sleep important?
Quality of sleep is as important, if not more so, than the length of sleep experienced. Quality sleep is sleep that is sufficient in depth (achieving deep sleep stages often enough), with the full sleep cycle being experienced several times a night. Quality sleep is restorative and refreshing, and is an important factor for adequate next-day functioning.
What is the role of melatonin in sleep?
Melatonin is a hormone released by the pineal gland in the brain that regulates the circadian rhythm. It is stimulated by darkness and acts as a sleep ‘time-cue’. Melatonin is an important physiological regulator of sleep. Studies have shown a link between declining melatonin production in the body, increasing age and insomnia.
Facts about sleep
• Approximately one-third of our life is spent sleeping.
• During sleep, the body has a chance to replace chemicals and repair muscles, other tissues and aging or dead cells. In children and young adults, growth hormones are released during deep sleep.
• During REM sleep breathing becomes more rapid, irregular and shallow, eyes move rapidly, heart rate increases and blood pressure rises. Limb muscles are temporarily paralysed. Brain waves during this stage resemble brain waves during wakefulness.
• Most dreams occur during REM sleep and some also occur (but to a lesser extent) in non-REM sleep stages.
• Sleep helps boost a healthy immune system, and can also balance the appetite by helping to regulate levels of the hormones that play a role in feelings of hunger and fullness. So, sleep deprivation may cause an urge to eat more, which can lead to weight gain.
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