2/9: Consciousness and Sleep
Sleep and the Brain
- Brain is active while sleep
- Sleep is a biological need, unique for each person
- Boredom unmasks sleepiness
- Sleep is an active process
- Snoring may signal the presence of sleep apnea, a sleep disorder
- Everyone dreams nightly
- Sleep need remains unchanged throughout adulthood
- People aren't good judges of whether or not they're sleepy
- Only short-term solution for sleepiness is a nap or caffeine
- Chronic sleep disorders can have diverse causes
- We have a circadian rhythm which is set by light and dark cycles, reason why body has hard time adjusting to night shifts
- Sleep disorders do not disappear without treatment
Consciousness
- Consciousness: our awareness of ourselves and our environments
- Sleep
= Unconsciousness
- Your brain continues to process external info while asleep
- brain continues to process internally generated info
- brain remains active when asleep
- generally, people can be easily awakened
- Need for sleep
- Several theories
- Sleep protects us from the dark
- evolutionary perspective: also from predators
- Sleep restores body tissues and brain reorganizes/repairs itself and consolidates memories
- Sleep allows us to grow
- pituitary gland releases growth hormone
- Sleep: Research
- Genetic Variability
- Humans will sleep at least 9 hours without interference
- 7-8 hours of sleep makes people live longer than without
- Sleep-wake cycle includes
- major period of sleep at night
- smaller period in the afternoon
- Naps
- focus attention
- help us make concentrated decisions
- Circadian Rhythm
- Biological clock regulates body rhythms every 24 hours
- largely affected by sleep-inducing hormome Melatonin
- produced by Pineal gland
- melatonin only produced in darkness
- bright light inhibits melatonin and resents the "clock"
- thought to conrtibute to depression, seasonal sleep disorder caused when natural light not present to help regulate sleep clock
- Morningness- Eveningness
- Horne and Ostberg, 1976
- stable preferences to times of day
- function of variations in circadian rhythms in body temperature and endocrine secretion
- research showed rhythms as short as 16 hrs as long as 50 hrs
- short biological rhythms
- hit peak body temperature and alertness earlier in the day and therefore get sleepier earlier
- Circadian arousal determines use of mental shortcuts
- morning during morning no use and vice versa
- morning during evening much use and vice versa
Sleep Stages
- Five Stages 5 ( regress through them)
- Sleep Cycle: 90 minutes
- Stage 1
- 5 min
- Fantastic images, hallucinations
- sensation of falling, floating, junping
- Stage 2
- 20 min
- can wake up without too much difficuklty but clearly asleep
- bursts of rapid brain activity( spindles)
- Stage 3
- 30 minutes
- Transitional
- beign to emit slow delta waves
- Stage 4
- 30 min
- delta waves
- slow-wave sleep
- hard to awaken
- end: sleepwalking/bedwetting
- Stage 5
- regress through stages 3-2: REM
- eye-movement phase
- 10 min
- Brain waves resemble of nearly awake stage 1
- but: heart rate rises, breathing increases, eyes twitch
- Beginning of a dream
- Brain's cortex is active but
- brain-stem blocks messages
Sleep Disorders
- 10-15% of adults have Insomnia:
- persistent problems in falling asleep/staying asleep
- Those who experience stress on average
- receive one hour less of sleep
- Narcolepsy: people spontaneously collapse into REM sleep
- Sleep apnea: stopping breathing during sleep intermittently
- 1 in 20 people (mostly overweight)
- causes the CNS to stop functioning
- Parasomnia:
- sleep walking, sleep talking, tooth grinding
- Night terrors: sitting up, walking around, talking, heightened heart rate/breathing
- mostly in children but can be in adults
- generally happen in DEEP sleep (stages 3 and 4) not REM
Sleep Deprivation- Higher risks for accidents, cause difficulty with work, lead to more mistakes and irritability
- Cohen, 1996
- adding/decreasing an hour affects # accidents
- Exhibit slower reaction times and increased errors on tasks
- Insufficient sleep
- decreased cognitive functioning
- mood
- work performance
- quality of life
- Cumulative
- Performance declines after 24 hrs of sustained wakefulness makes you 'stupid'
Sleep and Metabolism- Deprivation lowers level of leptin and raises levels of ghrelin
- they signal appetite activation and supression
- low levels of leptin = signal of starvation
- high levels of ghrelin = increased appetite
- body mass index propotional to sleep loss
- Facilitating sleep
- go to bed only when sleepy and keep bedroom cool
- sleep same time, get up same time
- use your bed only for sleep and relxaxing activities
- sleep in room that is fully darkened
- use muscle relaxation, visual imagert to calm before sleep
- avoid bedtime snacks
- don't nap after 3pm
- no distractions; noise generator to mask background noise
- avoid caffeine, alchol, and smoking in evenings
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