CNS 2

• What is sleep defined as in terms of awareness?

  Sleep is an awareness of the external world.
• What are the levels of consciousness?

  • Maximum alertness
  • Wakefulness
  • Sleep
  • Coma
• What are the consequences of not getting enough sleep?

  The consequences include sleep debt and tiredness.
• Where does the phenomenon of sleep occur in the brain?

  Such phenomenon occurs in the brain stem.
• What does an EEG measure?

  An EEG measures electrical activity of the brain using electrodes placed on the scalp.
• What are the types of brain waves during sleep?

  • Alpha
  • Beta
  • Gamma
  • Theta
  • Delta
• How is sleep divided?

  • Sleep is divided into two phases:
  • NREM (Non-Rapid Eye Movement)
  • REM (Rapid Eye Movement)
• What are the stages of NREM sleep?

  • NREM sleep has 4 stages:
  • S1: Theta waves interspersed with alpha waves
  • S2: Sleep spindles (bursts of activity)
  • S3: Delta waves appear
  • S4: Delta waves become dominant
• How does the amplitude of waves change through the stages of NREM sleep?

  The amplitude of the waves increases down the stages.
• What occurs during REM sleep?

  During REM, there’s rapid eye movement and muscle tone is decreased.
• What is paradoxical sleep during REM?

  Paradoxical sleep is when the EEG pattern of someone sleeping is similar to someone who is awake.
• How does brain oxygen consumption differ between REM and NREM sleep?

  The brain oxygen consumption is higher in REM than in NREM.
• What percentage of sleep does REM contribute to?

  REM contributes to 20-25% of sleep.
• What is the mechanism of sleep involving the RAS?

  • The RAS (reticular activating system) is involved in arousal and wakefulness.
  • Discovered by Moruzzi through ACh cell stimulation.
  • Stimulation in the RAS leads to awakening; in the thalamus, it leads to sleep.
• What neurotransmitters are released during the awake state?

  During the awake state, noradrenaline, histamine, orexin, and serotonin are released.
• What neurotransmitter is released during the sleeping state?

  During the sleeping state, GABA is released.
• What is the sleep center in the brain?

  The sleep center is a group of neurons in the ventrolateral preoptic nucleus (VLPO).
• What is one function of sleep?

  Memory consolidation