Sleep

• Where is sleep measured?

  in sleep laboratories, very expensive and time consuming to collect data
• What is the problem with sleep experiment?

  done in labs, not natural environment so may affect quality of sleep especially on first night
• Where are the 3 places elelctrical activity is recorded during sleep?

  • Electro-encephalogram (EEG)- Head
  • Electro-oculogram (EOC)- Eye
  • Electro-myogram (EMG)- Neck
• What are pre-sleep alpha waves?

  occur just before sleep, bursts of 8-12Hz activity in low amplitude / high frequency waves.
• How many stages of EEG sleep are there?

  4
• What happens as the stages go on?

  Progression: increase in amplitude, decrease in frequency.
• What are sleep spindles?

  occur in stage 2, 1 to 2s burst of 12-14Hz waves.
• What is a K complex?

  Single large upward, then downwards deflection, also occurs in stage 2 onwards
• What happens during sleep?

  the stages of sleep are cycled through every 90 mins, stages repeat around 6 times during a 8 hour sleep
• As the sleep progresses, more time is spent in...

  stage 1 during every cycle
• What is REM sleep?

  Rapid Eye Movement, occurs after with/after stage 1, associated with dreaming
• Just after stage 1, the EEG shows...

  there are short periods of awakeness
• What did Dement find about REM sleep?

  • 80% awakenings during REM sleep = dream recall.
  • 7% awakenings during nREM sleep = dream recall.
  • nREM dream recall – isolated experiences (e.g., perception of falling).
  • REM dream recall – more narrative
• Can people detect how long they spend in dreams?

  Dement found-Participants correct 92/111 cases when asked if they were awoken 5 or 15 minutes after onset of REM sleep
• What is the recuperation theory of sleep?

  says being awake disrupts homeostasis and sleep restores this (e.g. sleep restores energy levels)
• What is the evolutionary theory of sleep?

  says sleep evolved in humans to prevent accidents and predation at night, we are motivated to have it but dont need it
• What is seen in sleep in animals?

  • Large species differences in sleep – not related to body size / temperature.
  • e.g. sloths hardly move, yet need 20 hrs / day.
• Why do different species sleep different amounts?

  • Not consistent with recuperation theories in sleep.
  • Evolutionary theories – claims sleep related to how vulnerable you are asleep, and time spent eating / day
• Does exercise effect sleep?

  Little / No effect of exercise on sleep duration in humans (Youngstedt & Kline, 2006)
• What do recuperation theories predict about sleep deprivation?

  1. Increases in physiological / behavioural disturbances.
  2. After deprivation, missed sleep must be regained.
• What factors does sleep deprivation actual influence?

  mood, phsyiological function, molecular function, executive function (updating plans, memory)
• How well do people recover after sleep deprivation?

  (Dement 1978) Randy Gardner – 260 hours awake, 1st recovery night (14 hours sleep), then back to normal.
• What is the link between depression and sleep deprivation?

  • Vogel et al. (1975): Preventing REM sleep acts as an antidepressant.
  • Scherschlicht et al. (1982):Examined effects of 20 antidepressants. All reduced REM sleep, Most increased slow-wave sleep.
• What happens during REM deprivation?

  • preventing REM makes the body want it more
  • this deprivation on REM causes transient rebound, meaning REM increases
• What is the purpose of REM sleep beyond dreaming?

  • suggests its the default kind of sleep
  • more similar to being awake than asleep, as lack of REM doesnt cause tiredness
• What was found about sleep deprivation in animals?

  • After several days, experimental rats died.
  • But, post-mortem revealed swollen adrenal glands, gastric ulcers and internal bleeding, so death may be due to stress etc
• How was the hypothalamus found to play a role in sleep?

  • Contantin von Economo – studied the brains of those who died from the virus encephalitis lethargica.
  • Victims who had difficulty sleeping – Damage to anterior region
  • Victims who had difficulty staying awake – Damage to posterior region
• How is the reticular system involved in sleep?

  • Bremer (1936) performed transection here on cats, making them show a slow-wave sleep cycle, so wakefulness area must be around here
  • became known as the Reticular Activating system – low activity = sleep, high activity = wakefulness
• What is narcolepsy?

  • a rare long-term brain condition that can prevent a person from choosing when to wake or sleep
  • can result in excessive sleeping, sleep attacks, and cataplexy (temp loss of muscle control)
• What happens when we can move during REM sleep?

  sleep walking