Ultradian & Infradian rhythms

• Ultradian rhythms - cycles that last less than 24 hours
• Sleep stages - repeat every 90 minutes

  1. Light sleep
  2. Breathing & heart rate slows
  3. Deep sleep begins
  4. Very deep sleep
  5. REM
• The Basic Rest Activity Cycle - 90 minute cycle in the day, moving from a state of alertness to physiological fatigue
• Infradian rhythms - cycles that last over 24 hours
• Ultradian & Infradian rhythms evaluation:

  • Individual differences in sleep stages
  • Research support for BRAC - elite violinists would practice in 90 minute segments & would nap frequently
  • Exogenous cues in the menstrual cycle - sweat rubbed on the lips of women synched up their cycles - menstrual cycles can be affected by pheromones
  • The menstrual cycle influences mate choice - in ovulation, women prefer more masculine faces - kindness in long-term but 'good genes' for short term
• Infradian rhythms:

  • Cycles that last over 24 hours
  • Weekly cycle : male testosterone is higher on weekends
  • Monthly cycle : the menstrual cycle
  • Annual cycle : seasonal affective disorder
• Ultradian & infradian rhythms AO3:

  • Individual differences in sleep stages
  • Research support for BRAC
  • Exogenous cues in the menstrual cycle
  • The menstrual cycle influences mate choice
• Ultradian rhythms:

  • Cycles that last less than 24 hours
  • Sleep stages
  • The basic rest activity cycle