11- ultradian and infradian rhythms

Question 1

how long are ultradian rhythms

Answer 1

less than 24 hours

Question 2

what is an example of an ultradian rhythm

Answer 2

• 5 sleep stages

- BRAC

Question 3

explain the sleep stages

Answer 3

• patten alternates between REM(5) and NREM(1-4) sleep
• repeats every 90 min
• each stage shows distinct EEG pattern
• deep sleep = slow brainwaves and breathing and heart rate decrease
• during REM sleep = EEG resembles that of an awake person
• dreaming occurs in REM sleep

Question 4

explain the basic rest activity cycle (BRAC)

Answer 4

• 90 min cycle during the day
• move progressively from state of alertness to physiological fatigue
• human mind can focus for 90min and at the end runs out of resources leading to loss of concentration, fatigue and hunger

Question 5

how long are infradian rhythms

Answer 5

longer than 24 hours

Question 6

what is an example of an infradian cycle

Answer 6

the menstrual cycle

Question 7

explain the menstrual cycle

Answer 7

• considerable variations in length (23 cycle or 36 cycle)

- average is 28 days

Question 8

how do hormones regulate the menstrual cycle

Answer 8

• ovulation occurs halfway and oestrogen levels peak (16-32h)
• after this progesterone levels increase to prepare for possible implantation in the uterus

Question 9

positive evaluation of ultradian and infradian rhythms (2)

Answer 9

+ ULTRADIAN : elitle violinists limit practice sessions to 90 min and then nap to recover (best violinists napped more). same pattern among athletes, chess players and writers so fits with the BRAC
+ INFRADIAN : affect behaviour as women prefer feminised male faces when choosing long-term partner but prefer masculinised faces during ovulation

Question 10

negative evaluation of ultradian and infradian rhythms (2)

Answer 10

• individual differences in ultradian rhythms which are biologically determined and may be genetic (participants studied over 11 days and nights in lab where their sleep duration, time to sleep and time in each stage was noted. differences in all characteristics)
• if several women of childbearing age live together and don’t take contraceptives then their cycles synchronise due to pheromones (sweat taken from group and rubbed on upper lip of another group = synchronisation)