Biological rhythms - Infradian and ultradian rhythms

Question 1

Infradian rhythm

Answer 1

A type of biological rhythm that lasts longer than 24 hours e.g menstrual cycle and SAD

Question 2

Ultradian rhythm

Answer 2

A type of biological rhythm that lasts shorter than 24 hours e.g stages of sleep

Question 3

Menstrual cycle

Answer 3

• 28 days
• An endogenous system but may be influenced by exogenous factors e.g other women’s cycles
• Stern and McClintock study:
• Studied 29 women with irregular periods
• Pheromones were gathered from 9 women
• Pheromones were then rubbed on the upper lip of other women
• Found that 68% experienced changes in their cycle

Question 4

Seasonal affective disorder (SAD)

Answer 4

• Depressive disorder that has a seasonal pattern
• Psychologists think that melatonin could cause SAD
• During the night the pineal gland releases melatonin until dawn when light increases
• During winter, lack of light means melatonin production decreases

Question 5

Stages of sleep

Answer 5

Stage 1+2 = Light sleep - alpha waves with high frequency
Stage 3+4 = Deep sleep - delta waves with lower frequency
Stage 5 = REM sleep - theta waves

Question 6

Infradian - evaluation - strength

Answer 6

• Real world application
• Treatment for SAD is light therapy - reduces the effect of SAD in 80% people
• Preferred over antidepressants as it is regarded as safe

Question 7

Infradian - evaluation - limitation

Answer 7

• Methodological limitations
• Many other factors that can change the menstrual cycle e.g stress, changes in diet
• These may act as confounding variables
• Other studies have failed to replicate these findings
• Suggests menstrual synchrony studies are flawed

Question 8

Ultradian - evaluation - strength

Answer 8

• Improved understanding of age-related changes in sleep
• Slow wave sleep reduces with age
• Growth hormone is usually produced during sleep wake cycle
• Knowledge of ultradian rhythms has practical value

Question 9

Ultradian - evaluation - limitation

Answer 9

• Individual differences
• Research has found that the duration of each stage varies between people - especially in stages 3+4
• Researchers suggested these are likely to be biologically determined
• Difficult to generalise to everyone