Sleep

Question 1

Sleep

Answer 1

• State of disengagement from and non-responsiveness to the environment
  → characteristic postures
  → lack of behaviour
  → closed eyes

Question 2

Sleep cycles

Answer 2

• Awake/ alert → beta waves
• relaxed / drowsy → alpha waves
• stage 1 → theta waves (nrem)
• stage 2 → theta waves (nrem; sleep spindles, K - complexes)
• stage 3→ delta waves (nrem)
• stage 4→ delta waves (nrem)
• REM → similar to wake state (alpha waves)

Question 3

REM sleep

Answer 3

• Distinctive stage of sleep characterized by rapier back-and forth movements of the eyes
  → when most dreaming occurs
  → loss of muscle tone (REM atonia) which limits the ability to move
  → variability in thermoregulation, respiration, circulation, etc.
• awake → high levels of NA (noradrenaline) and serotonin
• REM sleep→ high levels of arousal

Question 4

Circadian rhythms

Answer 4

• Cycles of metabolic and behavioural processes which correspond to the rotation of the earth
  → melatonin: low during the day and peaks at night
  → body temperature: high during the day and low at night
  → alertness and reaction time low at night
• wakefullness maintained by brainstem and hypothalamus, sleep produced by inhibition from a part of the hypothalamus

Question 5

Types of circadian rhythms

Answer 5

• Diurnal: awake during the cray, asleep at night (humans, primates, birds, reptiles)
• nocturnal: awake at night, asleep during the day (owls, bats, raccoons)
• crepuscular: awake at dawn and dusk, asleep at night and during the day (cats, rabbits, foxes)
• cathemeral: irregular, frequent, or seasonally-based cycles (lions, lemurs, coyotes)

Question 6

Parasomnia

Answer 6

• Abnormalities in their experiences of sleep (may or may not be of medical concern)
• dreaming:
  → nightmares: dreams with vivid content and intense negative valence (anxiety, fear, disgust, etc.)
  → nightmare disorder: repeated nightmares which impede quality sleep via awakenings and an inability to fall back asleep (daytime sleepiness/impaired cognition)
  → night terrors: intense expressions of terror and physiological arousal during sleep
  → REM atonia: failure to initiate/maintain can lead to involuntary movements (if this occurs while falling asleep or while waking up → sleep paralysis)
  → sleepwalking (somnambulism): getting out of bed and walking around while still asleep

Question 7

Dyssomnia

Answer 7

• Disturbances in falling asleep, remaining asleep, or of excess sleepiness
  → insomnia: difficulty falling asleep
  → hypersomnia: excessive sleep
  → excessive daytime sleepiness
  → narcolepsy: excessive daytime sleepiness and frequent, short episodes of daytime sleep

Question 8

Circadian rhythm disorders

Answer 8

• Characterized by disturbances in the timing of sleep
  → sleep phases are variable within individuals depending on internal and external factors (activity levels, exposure to light, seasonality)
  → advanced sleep phase disorder: strong tendency to fall asleep and wake up earlier than most people / than is desirable
  → delayed sleep phase disorder: string tendency to fall asleep and wake up later than most people / than is desirable
  → non-24 hour sleep-wake syndrome: when one’s circadian rhythm doesn’t equal 24 hours (longer cycle will lead to delay in the timing of sleep/wakefulness); more common in visually-impaired people
  → irregular sleep-wake rhythm: no discernible pattern to sleep and wakefulness (seen in people with brain injuries or neurodegeneration)

Question 9

jet lag

Answer 9

• Occurs when one’s circadian rhythm desynchronizes from the environment due to rapidly crossing many lines of longitude
• symptoms include fatigue, loss of concentration, gastrointestinal discomfort, loss of appetite, sleep disturbances
  → seventy of symptoms and speed of recovery depends on the distance and direction of travel

Question 10

Shift work

Answer 10

• For employment reasons, some people are required to maintain cycles of sleep and wakefulness that do not correspond to their internal rhythm or to the diurnal rhythm of the sun (overnight or early morning)
• shift work disorder: when shift work results in sleep disturbances such as insomnia, excessive sleepiness, poor quality of sleep
  → chronic sleep deprivation can lead to long-term health problems, poor cognitive function, and increased workplace accidents
  → can interfere with interpersonal and social relationships

Question 11

Sleep apnea

Answer 11

• disorder in which breathing repeatedly stops and starts during sleep
  → symptoms include frequent awakening, low-quality sleep, daytime sleepiness, headaches, low concentration, irritability
• types:
  → obstructive: when the throat relaxes and blocks the airway
  → central: when the brain ceases to communicate with the muscles that control breathing