Lesson 11 - Infradian and Ultradian Rhythms

Question 1

Ultradian Rhythms

Answer 1

• Span a period of less than 24 hours
• For example the 5 sleep stages
• 1,2,3,4 are Non-Rapid Eye Movement sleep
• 5 is Rapid Eye Movement
• The cycle repeats itself every 90 minutes

Question 2

EEG Patterns

Answer 2

• As a person enters deep sleep, their brainwaves slow and their breathing and heart rate decreases
• During REM sleep, the EEG pattern resembles that of an awake person - dreaming occurs during this stage

Question 3

Basic Rest Activity Cycle (BRAC)

Answer 3

• Kleitman 1969 - 90 minute cycle found during BRAC
• Suggested that the cycle continues whilst we are awake
• During the day, rather than moving through the sleep stages, we move progressively from a state of alertness into a state of physiological fatigue
• Studies suggest that the human mind can focus for 90 minutes
• Towards end of 90 minutes the body beings to run out of resources, resulting in loss of concentration, fatigue and hunger

Question 4

Ericsson et al 2006 - Violinist AO3

Answer 4

• Studied a group of elite violinists and found among this group practice sessions were limited to 90 minutes at a time
• Violinists frequently napped to recover from practise, with the best ones napping more
• The same pattern was found among athletics, chess players and writers

Question 5

Tucker et al 2007 - Individual Differences AO3

Answer 5

• Suggests there are individual differences in ultradian rhythms which are biologically determined and may even be genetic in origin
• Participants were studied over 11 consecutive days and nights in a lab environment
• Researchers assessed sleep duration, time taken to fall asleep and the amount of time in each stage
• They found differences in all of these characteristics

Question 6

Infradian Rhythms

Answer 6

• Spans a period of longer than 24 hours
• Example - menstrual cycle, lasts about 1 month
• Menstrual Cycle
  
  • Hormones regulate the menstrual cycle
  • Ovulation occurs roughly halfway through the menstrual cycle, when oestrogen levels are at their peak - lasts 16-32 hours
  • After ovulation, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus

Question 7

Penton-Voak 1999 - Behaviour AO3

Answer 7

• Can affect behaviour
• Found that women express a preference for feminised male faces when choosing a partner for a long-term relationship
• However, they showed a preference for masculinised faces during ovulation

Question 8

Synchronised Cycles AO3

Answer 8

• Menstrual cycle not only governed by infradian rhythms
• When several women live together, their menstrual cycles sync
• Study - Samples of sweat collected from one group of women and rubbed onto upper lip of another group of women
• Cycles then synchronised
• Suggests that it is due to pheromones