Facts about
The Nature of Sleep

sleep

Sleep is such an important part of our lives, yet many of
us don’t pay much attention to it. It is usually not until wehave problems with sleep that we notice it and start totry to understand the nature of sleep. As well as humans,other mammals, reptiles and birds all sleep, while fish,amphibians and insects do not (although they may rest).
Some animals sleep in many short bursts, while others,
like humans, prefer to sleep in one long block.
We all know what sleep looks like - we recognise asleeping person because they have their eyes closed, willusually be lying down, breathing in a slow rhythm, withrelaxed muscles and generally keeping still, although they
may rearrange their bodies every so often. Being asleep isbeing unconscious to most things happening around you,but is different from a coma or passing out because
sleeping people can be woken up, by loud noises orbright lights or touch.

Stages of Sleep
Research tells us that there are two types of sleep:
 REM rapid-eye-movement sleep:

this type of sleep occurs for about
25% of the night, and is characterisedby electrical activation of the brain,very relaxed muscles and body
becoming immobile, and rapid eye movements as theeyes dart back and forth under closed eyelids. REM
sleep provides energy to the brain and body andsupports daytime performance. Dreams often occur
during REM sleep, although they can occur at any stage.
 NREM non-rapid-eye-movement sleep: this typeof sleep occurs during the other 75% of the time, andcan be further broken down into 4 stages:
 Stage 1: this stage is light sleep, between being
awake and falling asleep
 Stage 2: this stage is the onset of sleep, when theperson begins to become disengaged from theirsurroundings. Body temperature drops andbreathing and heart rate become regular.
 Stages 3 & 4: These stages are the deepest andmost restorative sleep, known as ‘delta sleep’ Stage 3 is a transition into Stage 4, or ‘true delta.’
During these stages, blood pressure drops,
breathing becomes slower, muscles are relaxed andreceiving more blood supply, tissue growth andrepair occurs, and hormones are released(including growth hormone, which is why growing
teenagers need to sleep more).

Role and Function of Sleep
Sleep is essential to humans, just like air, water and food.
When necessary, people can cope without sleep for
periods of time, but the longer we are awake the stronger
the urge to sleep becomes.
The exact role and function of sleep has been a topic ofdebate for researchers, but most agree that sleep serves a
restorative purpose, both psychologically andphysiologically. It is thought that delta sleep (stages 3 & 4) ismost involved with restoring the body and physical energy,
while REM sleep is most important for restoring mental
function such as memory and concentration.
Sleep is important for general physical health, restoringenergy, repairing injuries or illness, growth, psychologicalwell-being and mood, concentration, memory, work
performance, and getting along with others.

Effects of Lack of Sleep
People vary in terms of how much sleep they need - while
the average sleep duration for adults is 7-8.5 hours pernight, some people function well with 4-5 hours and othersrequire 9-10 hours. Whatever your individual needs, lack ofsleep or poor sleep quality can have effects including: Poor attention, concentration andmemory
 Irritability and other mood disturbances Impaired judgement and reaction time Poor physical coordination (dangerousfor driving)

The seriousness of these effects depends on how bad thesleep deprivation is (e.g. less sleep vs. no sleep; one night’s
poor sleep vs. chronic problems) and the tasks andresponsibilities of the day. If you have ongoing problems
with sleep, it is important to seek help.

How Well do Good Sleepers Sleep?
Good sleepers usually take less than 30 minutes to fallasleep at the beginning of the night and will wake up onceor twice during the night. In other words, it is unrealistic to
expect to fall asleep immediately on getting into bed or tonever wake up at all during the night. Even the best
sleepers in the world don’t achieve this! Also, everybody,even the best sleepers, will have a night now and thenwhen it takes them a long time to get to sleep. This is often
triggered by a stressful event and will usually pass after anight or two. Similarly, everybody will have a night now andthen when they find it difficult to get back to sleep after
waking in the middle of the night.

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http://www.cci.health.wa.gov.au regarding the information from this website before making use of such information.

See website www.cci.health.wa.gov.au for more handouts and resources.

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