Ultradian rhythms

• What are ultradian rhythms?

  Cycles lasting fewer than 24 hours
• In what pattern can ultradian rhythms be found?

  In the pattern of human sleep
• What are the two main types of sleep in ultradian rhythms?

  REM and NREM sleep
• How many stages are there in the sleep cycle?

  Five stages
• What happens during REM sleep?

  Brain waves speed up and dreaming occurs
• How often does the sleep cycle repeat?

  About every 90 minutes
• What is the first stage of the sleep cycle?

  Light sleep
• What characterizes stages 3 and 4 of sleep?

  They are deep sleep stages with delta waves
• What brainwave patterns are associated with stages 1 and 2?

  Alpha waves progress to theta waves
• What happens to the body during REM sleep?

  The body is paralyzed
• How many full sleep cycles can a person experience in a night?

  Up to five full cycles
• What is a challenge in studying sleep cycles?

  Individual differences make patterns difficult
• What did Tucker et al. (2007) find about sleep stages?

  Significant differences in duration of stages
• Why is the controlled lab setting important in Tucker et al.'s study?

  It isolates biological differences from situational factors
• What should psychologists consider in ultradian rhythm research?


  Other situational factors may also play a role
• What is a potential issue with how sleep research is conducted?

  It may be invasive and affect sleep patterns
• What does lack of ecological validity in sleep studies imply?

  Results may lead to false conclusions
• Who is Randy Gardener?

  A person who stayed awake for 264 hours
• What problems did Randy Gardener experience during his wakefulness?

  Blurred vision and disorganized speech
• How much sleep did Randy Gardener recover after his experience?

  Only 25% of his lost sleep
• What percentage of Stage 4 sleep did Randy recover?

  70% of Stage 4 sleep
• What percentage of REM sleep did Randy recover?

  50% of his REM sleep
• What does Randy Gardener's case highlight about ultradian rhythms?

  They have a large degree of flexibility