U4AOS1

• psychological construct


  an agreed upon description and understanding of psychological phenomena that cannot be overly measured or observed
• sleep

  • a reversible behavioural state of perceptual disengagement from the environment
  • a regularly occurring altered state of consciousness
  • partial or social suspension of conscious awareness
• sleep episode

  the full duration of time spent asleep (typical person will experience around 6 cycles throughout their sleep episode)
• sleep cycle

  a 90 minute period where an individual progresses through stages of REM & NREM 1-3 sleep
• REM sleep

  • more active brain
  • less active body
  • more vivid dreams
  • 25-30% of cycle
  • EEG shows high frequency and low amplitude patterns
• NREM sleep

  • less active brain
  • more body movement
  • 3 stages
  • less vivid dreams
  • 75-80% of sleep cycles
  • EEG shows high amplitude and slow frequency patterns
• EEG

  • measures brain waves
  • frequency = the number of brain waves that occur per second
  • amplitude = measures the intensity and height of the brain waves
• EMG

  • measures muscle activity and tone
  • attaches to skin around specific muscles (legs, arms, torso, etc)
• EOG

  • measures muscles surrounding the eyes
  • changes in rapid eye movements over the different stages of sleep
• sleep diary

  • subjective self-report tool that collects quantitative and qualitative data used by a person to track their own sleep-wake patterns
  • examples include
  • time trying to fall asleep
  • number, time and length of awakenings during sleep
  • time of waking up
  • how well rested they feel
  • how sleepy they feel during the day
  • activities during the day that may impact on sleep (eg. coffees consumed, naps taken, etc)
• video monitoring

  • a sleep study tool used to collect qualitative visual and audio information about a person’s sleep
  • measures externally observable physiological changes throughout sleep episode
  • examples include
  • changes in posture / sleep position
  • amount of tossing and turning
  • sleep-related breathing problems
  • behaviours associated with sleep-walking
• circadian rhythm

  • changes in bodily functions that occur as part of a cycle with duration of 24hrs
  • controlled by SCN
• SCN

  • master biological clock located in hypothalamus
  • regulates sleep-wake cycle
  • receives info about incoming light, and sends neural messages to nearby pineal glands to secrete melatonin
• melatonin

  • a hormone that makes us sleepy / drowsy
  • produced by the pineal gland with the signal of SCN
  • production depends on light detected, so it can regulate our sleep-wake cycle
• ultradian rhythm

  • cycle inside the cycle
  • changes in bodily functions or activities that occur as part of a cycle shorter than 24hrs
  • eg. heartbeat, hunger, respiration, etc
• circadian vs ultradian rhythms


  ultradian = recurrent period / cycle repeated throughout 24hr day (eg. hungry multiple times a day), circadian = completes one cycle daily (eg. ideally should be sleep)
• infants demands for sleep (0-2 months)

  • sleep required = 16hrs
  • REM = 50%, NREM = 50%
  • sleep onset can occur at any time
  • irregular duration
  • more than half of their sleep = REM
  • 2-3 months = circadian rhythm comes into play
  • 12 months = 14-15hrs per day (longest episode at night)
• childrens demands for sleep (2 months - 5 years)

  • sleep required = 10-11 hrs
  • REM = 10-25%, NREM = 75-80%
  • total sleep time decreases to 11hrs after 2 weeks
  • proportion of REM decreases, NREM increases
• adolescents demands for sleep (11-20yrs)

  • sleep required = 9hrs
  • REM = 20%, NREM = 80%
  • total sleep time & REM sleep decreases
  • duration of REM trends remains constant
  • amount of time spent in NREM 3 decline, time spent in NREM 2 increases
  • late adolescence = amount of SWS decreases
• adult demands for sleep (20-65yrs)

  • sleep required = 7-8hrs
  • REM = 20%, NREM = 80%
  • gradual loss of NREM 3
• elderly demands for sleep (65+yrs)

  • sleep required = 6-7hrs
  • REM = 20%, NREM = 80%
  • time spent in NREM 3 disappears
  • sleep more fragmented with more awakenings
  • ASPS (more sleepy in evening, wake up earlier)
• partial sleep deprivation


  inadequate quality & quantity of sleep when an individual sleeps for some duration within a 24hr period
• full sleep deprivation


  when an individual has no sleep within a 24hr period
• affective effects of sleep deprivation

  • mood change (emotional regulation & reactivity impaired)
  • inability to control emotions (amplified & irritable)
  • impaired facial recognition of emotions
  • reduced emotional empathy
  • increase in impatience and aggression
• behavioural effects of sleep deprivation

  • disoriented, partially aware & groggy
  • primary effect on behaviour functioning (excessive sleepiness)
  • difficulty maintaining alertness
  • fatigue
  • slower reaction times
  • microsleep
  • poor performance at school / work
• sleep inertia

  performance impairment that occurs immediately after awakening
• cognitive effects of sleep deprivation

  • reduced alertness and concentration
  • greater errors in simple, monotonous and repetitive tasks
  • reduced ability for complex tasks
  • for children, impacts upon
  • verbal creativity
  • visual / spatial ability
  • hand-eye coordination
  • poor performance on learning & memory tasks
• BAC vs sleep deprivation

  • 17 hrs sleep deprivation = BAC 0.05% (legal limit)
  • 24 hrs sleep deprivation = BAC 0.10%
• cognitive effects of sleep deprivation / BAC

  • slower mental processing
  • reduced ability and speed in decision-making
  • decreased ability to problem solve & reason
• affective effects of sleep deprivation / BAC

  • negative mood (irritable, short-tempered)
  • having difficulty judging the emotions of others
  • having amplified emotions
  • an interference with cognitive performance
• sleep disorder


  sleep disturbance regularly disrupts sleep, causes stress or impairment in important areas of everyday life during normal waking hours
• circadian rhythm sleep disorders

  • disorders that leads to a misalignment of sleep-wake cycle & circadian rhythm that interferes with the typical regulation of the circadian rhythm
  • primarily attributed to mechanisms / processes that generate sleep and produce difficulty initiating, maintaining and / or timing sleep
  • disruption may be caused by
  • natural changes / malfunctions of biological mechanisms
  • misalignment of actual sleep-wake cycle and the one demanded by school/work schedules
  • misalignment of day / night cycle with physical environment
• delayed sleep phase syndrome (DSPS)

  • typical for adolescents
  • stay up later in the evening, feel sleepy at a later time, get insufficient night time sleep on the weekdays, difficulty waking in the morning
• sleep debt

  sleep that is owed / missed, difference between amount of sleep needed and had
• advanced sleep phase disorder (ASPD)

  • typical for elderly
  • naturally feel sleepy and wake earlier
  • compelling evening sleepiness, early sleep onset, awakening earlier than desired
  • influences
  • age-related deterioration in SCN (sleep-wake cycle not regulated)
  • reduction in melatonin production evident among older people
  • shift in circadian timing of melatonin secretion (2-4hrs earlier)
• shift work

  • excessive sleepiness when awake at work & impaired sleep at home on a regular basis (insomnia)
  • leads to
  • sleep debt accumulates
  • experience problems with quality & quantity of sleep
  • tiredness
  • tendency to sleep 2x during day
  • problems falling asleep due to environmental conditions (light)
  • frequent rotating sleep schedules harder to adjust
  • schedule with 3 weeks preferable
  • when changing shifts, better to move it forward (day shift to afternoon shift to night shift)
• bright light therapy

  • timed exposure of the eyes to intense but same amounts of light
  • aims to reset the biological clock regulating a person’s sleep-wake cycle to align it with the sleep / wake schedule they desire (15 mins - 2hrs a day)
  • DSPS = BLT early morning (6-8am) to advance sleep-wake cycle
  • ASPD = BLT early night to delay cycle to later time
  • shift work = BLT in evening, avoiding bright light in mornings
• sleep hygiene

  • practises that tend to improve and maintain good sleep and full daytime alertness
  • behaviours & environmental factors
  • regular relaxing sleep schedule & bedtime routine
  • associating bed & bedroom with sleep
  • avoid stimulating activities an hour before bed
  • get up when you cannot sleep
  • avoid napping during waking period
  • exercise during day
  • avoid eating just before sleep
  • create a comfortable sleeping environment
  • ensure adequate exposure to natural light
• zeitgebers

  • environmental cues which help the SCN synchronise the circadian rhythms to the 24hr day
  • includes: light, temperature, eating / drinking patterns
• light as a zeitgeber

  • daylight
  • advances in sleep wake cycle = light in morning + early afternoon
  • delays in sleep wake cycle = light late afternoon, early evening
  • blue light
  • suppresses melatonin production (keeps us alert)
  • harmful in evening hours (affects sleep quality / quantity)