U4 AOS1 (Sleep) Flashcards
Sleep as an ASC
A regular ASC that typically occurs spontaneously and characterised by a loss of conscious awareness and is naturally occurring
Characteristics of sleep as an ASC
- lower level of awareness: very little awareness of external environment
- fewer content limitations: relinquish conscious control of thoughts
- controlled/automatic processes: performing other tasks generally impossible, excluding sleep walking
- percep/cog distortions: attention to sensory stimuli lowered and thoughts more organised and unrealistic
- emotional awareness: increased or decreased causing nightmares or dreams
- less self control: May snore, drool, grind teeth, sleep talk
- distorted time orientation: can’t predict how long you have slept for without clock
Circadian Rhythm
- biological cycle with an approx 24hr duration
- it is not a sleep cycle alone
- superchiasmatic nucleus: regulates sleep wake cycle located in hippocampus. Analyses strength of light and stimulates pineal gland to release melatonin
Ultradian Rhythms
- biological rhythm that occurs within less than 24hrs
- sleep portion of sleep wake cycle is ultradian
- 90min cycle where REM and nREM is altered
Proportion of REM and nREM
80% nREM
20% REM
REM Sleep
- period of sleep where eyeballs move rapidly under closed eyelids
- brain is very active during REM sleep (beta waves)
- often referred to as paradoxical sleep
NREM 1
- some slow rolling eye movements
- Hypnic jerks
- very light sleep and very brief
NREM 2
- Decrease HR/body movement/temp/blood pressure
- breathing becomes more regular
- rolling eye movements stop
NREM 3
- moderately deep sleep
- difficult to wake and likely to be disorientated when woken
- continued decrease in bodily functions
- continued relaxation of muscles
NREM 4
- deepest stage of sleep
- very difficult to wake
- sleep inertia experienced when woken
What is the restorative theory?
- sleep allows body to recharge, recover from physiological/psychological work and allows growth processes
- activates growth hormones, increases immunity, increases alertness, enhances mood, consolidates memory
Restorative effects of nREM
Restores the body
Restorative effects of REM
Restores the mind (cognitive/psychological processes)
Support for Restorative Theory
- marathon runners have greater amounts of nREM
- growth hormones are released during nREM
- nREM sleep improves immunity of body against illness
- REM improves memory consolidation
- REM improves alertness
Criticisms for Restorative Theory
- if sleep is restorative then it is counter intuitive to have the mind so active in this time
- would be assumed that those who do little exercise sleep less but this is not the case
- those bed ridden experience same proportion of nREM sleep despite not needing significant body restoration
Evolutionary Theory
Survival is the main purpose of sleep
- need to find food (cows sleep limited due to small energy from grazing)
- conserve energy (bears hibernate when food sources are scarce to avoid unnecessary energy expenditure)
- avoid predators (mice sleep to avoid predators)
Support for Evolutionary Theory
- vulnerability to predators: mice
- need to find food: cows
- conserve energy: Bears
Criticism of Evolutionary Theory
- theory shows why sleep is important but not why it’s a MUST
- loss of awareness during sleep makes animals vulnerable to predators
Patterns of one nights sleep
- as each cycle progresses, deepness of sleep decreases
- periods of REM sleep increase
Sleep as an Adolescent
- time of melatonin release occurs 1-2hrs later than normal
- individual feels sleepy later
- changes the timings of major sleep episodes
- known as a sleep wake cycle shift
Melatonin
Hormone responsible for inducing sleep that is released from the pineal gland
Sleep in Shift Work
- artificial light allows human’s to utilise more hours in day
- individuals exposed to excessive night time light and alter sleep wake schedule
- asynchrony between circadian sleep systems
- risks: include safety hazards and extensive health problems ranging from mood disorders to cancer
Shift Work Symptoms
- at least one month of complaints of excessive sleepiness and insomnia in relation to work schedule falling during during time of habitual sleep
Shift Work Disorders
- associated with poor performance
- cardiovascular/gastrointestinal/reproductive problems
- accidents
- illness
- depression
- bright light therapy and avoidance of light at wrong times of day can resync schedule