what is the nature of sleep? most people think of sleep as a state of unconsciousness, punctuated by...
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What is the nature of sleep?Most people think of sleep as a state of
unconsciousness, punctuated by brief periods of dreaming. Sleep is actually a
state of altered consciousness, characterized by
certain patterns of brain activity and
inactivity.
Facts about SleepMost adults need seven or eight hours' sleep a
nightA giraffe sleeps for an average of 1.9 hours a dayA cat sleeps for an average of 12 hours a dayFamous figures like, Margaret Thatcher,
Napoleon and Florence Nightingale only needed four hours
An adult sleeping for eight hours will burn approximately 50 calories
Almost two thirds of the population claim they do not get enough sleep
Why do we sleep? While the exact function of
sleep is unknown, but according to the evolutionary theory, sleep evolved to conserve energy and protect us from predators.
According to the repair/restoration theory, sleep is thought to be necessary for restorative/healing value, both physically and psychologically.
Loss of Sleep… suppressed immune
system impaired creativity and
concentration slowed performance
and misperceptions on monotonous tasks
Benefits of Sleep
restoration of energy repairing of brain and
body tissuerelease of growth
hormones
Stages of SleepEach night, we go
through four to five cycles of distinct sleep stages.
Each stage has its own rhythm and corresponding changes in brain activity and behavior.
The average person progresses through the stages of sleep 3 to 6 times per night.
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Stage 0
This period of falling asleep is also called the hypnagogic state. (hip-na-gog-ic)
relaxed with eyes closedbrain briefly emits alpha waves = associated
with absence of concentrated thought and relaxation
Stage Isensory images and slow rolling eye
movements theta waves on an EEG-- lower in
amplitude and frequency than alpha waves
pulse slows more, muscles relax, breathing uneven
If awakened during this stage, you would report that you were “just drifting.”
Lasts from 30 seconds to about 10 mins.
Stage IIBrain waves shift from low-frequency
waves to high frequency wavesEyes roll slowly from side to sideAbout 50% of our sleep time is in
stage II
Stage IIIAbout 30 minutes into sleep=
drift down into a deeper level of sleep
larger-amplitude delta waves begin to sweep your brain every second or so
Stage IVDeepest sleep of allOften difficult to wakeLarge, regular Delta Waves
occurring more than 50% of the time
If awakened by a loud noise = may feel disorientated
Talking out loud, sleepwalking, and bed-wetting—all of which may occur at this stage—leave no trace on the memory
Rapid Eye Movement =REM sleepmuscles are more relaxed, eyes begin to move
rapidly pulse rate becomes irregular levels of adrenal and sexual hormones in blood
riseface or fingers twitch large muscles in your arms and legs are paralyzed
brain shows waves that closely resemble those of
a person fully awake = REM sleep is called active sleep
Stages of Sleep--REMStages I-IV are called NREM
(non-REM) or quiet sleep. It is during REM sleep that
almost all dreaming normally takes place.
REM sleep lasts about 15-45 minutes after which you retrace the steps to Stage IV.
Sleep Disorders: When Sleep Becomes a Problem
Are you one of those lucky people who takes sleep for granted? If so you may be surprised to discover the following facts:•An estimated 2/3 of adults suffer from sleep problems and about 25 percent of children under age 5 have a sleep disturbance•One in five adults is so sleepy during the day that sleepiness interferes with their daily activities. •Each year [Americans] spend more than $98 million on over-the-counter sleep aids and another $50 million on coffee to keep them awake during the day.
Sleep Disorders: Dyssomnia & ParasomniaPsychologists divide sleep disorders into two
major diagnostic categories: 1) Dyssomnias: problems in the amount,
timing, and quality of sleep2) Parasomnia: abnormal disturbances
occurring during sleep
Sleep Disorders: DyssomniaInsomnia: “lack of sleep” persistent difficulty falling asleep or staying asleep, or
wake up too early 10% of the population serious insomnia = other medical or psychological
disorders also (alcohol and other drug abuse, anxiety disorders, and depression)
most popular treatment = drugs—either over the counter pills or prescription tranquillizers and barbiturates (which decrease Stage 4 and REM sleep therefore affect the quality of sleep)
Sleep Disorders: DyssomniaSleep Apnea: “no breathing” repeated interruption of breathing during sleep air passages to the lungs are physically blocked
or the brain stops activating the diaphragmmay kill neurons in the brain critical for
learning and memorycan also lead to high blood pressure, stroke,
heart attack
Sleep Disorders: DyssomniaNarcolepsy: sudden and irresistible onset of sleep during
normal waking hours afflicts one person in 2000 runs in familiesREM-like sleep suddenly intrudes into the
waking state of consciousnesssudden attacks of muscle weakness or paralysisLong daily naps and stimulant or
antidepressants may help reduce the frequency
Sleep Disorders: ParasomniasNightmares: Anxiety-arousing dreams generally
occurring near the end of the sleep cycle, during REM sleep
Night Terrors: Abrupt awakenings from NREM (non-rapid-eye-movement) sleep accompanied by intense psychological arousal and feeling panic
Sleep walking: Tends to accompany night terrors also occurs during NREM sleep.
Sleep talking occurs in REM and NREM sleepThese events are more common in children, but
they can also occur in adults, usually during times of stress or major life events.
Help with Sleep DisordersDuring the Day:Exercise—it works away tensionAvoid Stimulants—coffee, tea, soft drinks, chocolateAvoid Late Meals & Heavy DrinkingStop Worrying—focus on problems at a set time earlier in the dayUse Pre-sleep Rituals—follow the same routine every night
In Bed:Use progressive muscle relaxation-tense and relax muscle groupsYoga-type gentle exercises to help relaxationImagine yourself in a tranquil settingUse deep breathingWarm bath or shower can induce drowsiness
Psychoactive Drugs Overview:http://
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