L17 Sleep

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  1. Wake signals branch 1: neurons in the upper pons produce acetylcholine, which activates areas of the thalamus responsibe for the channelling signals to the cerebral cortex (the site of consciousness).
  2. Wake signals branch 2: neurotransmitters are produced in the pons, hypothalamus and other nearby regions. They prime the cerebral cortex to receive signals from the thalamus.
• Biological clock - the brain tiring:

  • brain slows down, less firing of neurons
  • SCN sends info to the pineal gland when it becomes dark which releases melatonin
• Biological clock - sleeping:

  • VLPO neurons are activated releasing GABA and gala in which bind to receptors in the hypothalamus and pons to inhibit the ascending arousal system
• What is a polysomnograph?

  EEG + eye tracking + other measurements
• What are delta waves?


  Brain waves that are associated with deep sleep and are characterized by high amplitude and low frequency.
• What are theta waves?

  Theta activity has a frequency of 3.5 to 7.5 Hz and is classed as “slow” activity. It is seen in connection with creativity, intuition, daydreaming, and fantasizing and is a repository for memories, emotions, sensations. Theta waves are strong during internal focus, meditation, prayer, and spiritual awareness.
• What are alpha waves?

  Brain waves with a frequency of 8-13 Hz, associated with relaxed wakefulness and a calm mental state. Emerges with closing your eyes .
• What are beta waves?

  Brain waves with a frequency of 12-30 Hz, associated with alertness and active thinking.
• What are gamma waves?

  Gamma waves are a type of brainwave that have a frequency of 30-100 Hz and are associated with higher cognitive functions, such as memory, attention, and problem-solving.
• What are the sleep stages?

  Stage 1: theta waves, light sleep

  stage 2: light sleep, sleep spindles

  stage 3: delta waves, slow-wave sleep, deep sleep

  stage 4: REM sleep
• Sleep deprivation affects:

  • thermoregulation - regulation of body temperature
  • immune system - initial response to disease and restoration is disrupted
  • metabolism
• What is narcolepsy?

  Frequent unexpected periods of sleepiness during the day.

  • REM sleep intrudes into wakefulness
  • cause = lack of the hypothalamic cells that produce and release orexin
  • treated with stimulant drugs
• Sleep is critical for memory consolidation:

  • integrating memories into an ordered framework
  • assimilating new memories with older knowledge
  • facilitating the abstraction of general rules