Infradian Rythm

Question 1

What is an infradian rhythm?

Answer 1

It is a biological rhythm that lasts longer than 24 hours it could be weekly, monthly or annually.

Question 2

What Infradian rhythms do people have?

Answer 2

• Menstrual cycle

- Seasonal affective disorder

Question 3

Describe the menstrual cycle

Answer 3

• The hypothalamus (endogenous pacemaker) will signal the pituitary gland to release hormones to release the egg.
• signals are also sent to the ovaries to secrete oestrogen which will promote egg growth and ripen them for ovulation, it will also secrete progesterone which will thicken the uterus lining to prepare it for an implantation of an embryo. The average menstrual cycle lasts for 28 days but it can vary for different females.

Question 4

Identify exogenous zeitgebers for the menstrual cycle?

Answer 4

-contraceptives (artificial hormones) and pheromones from other women

Question 5

Describe Seasonal affective disorder

Answer 5

-SAD is a infradian rhythm that can occur annually, it is a disorder that causes someone to acquire depressive symptoms as a result of the decrease in day light (Exogenous zeitgebers) during winter which causes the secretion of melatonin (endogenous pacemaker) from the pineal gland (endogenous pacemaker) to be prolonged which promotes a feeling of tiredness which also causes low mood.

Question 6

Identify AO3 paragraphs for Infradian rhythms

Answer 6

• McClintock and Stern
• Practical application (Phototherapy)
• Terman

Question 7

Outline McClintock and Stern’s research aim, method, findings and conclusion

Answer 7

Aim: to investigate the effect exogenous zeitgebers had on the menstrual cycle

Method: Stern studied 20 Women aged 20-35 with a history of irregular ovulation over the course of ten years. Pheromones were gathered from 9 women who had regular ovulation by putting a cotton pad underneath their arms for eight hours and then they were frozen and put in alcohol to disguise the odour. The pads were wiped under the noses of participants who had irregular ovulation.

Findings: Stern found that 68% of the 20 women had responded to the pheromones and their ovulation became regular.

Conclusion: The menstrual cycle is more dependant on exogenous zeitgebers as a result of more than have of women’s bodies responding to the pheromones.

Question 8

Outline Termans study aim, method, findings and conclusion

Answer 8

Aim: To investigate the effect day light (exogenous zeitgebers) had on individuals with seasonal affective disorder

Method:

• 124 participants were investigated aged 18-65 who had SAD.
• Over three weeks participants were placed into certain conditions
• the first condition would involve participants recited bright light therapy in the morning
• the second condition received it during the evening
• the third condition received a placebo treatment

Findings:

• Those who received bright light therapy in the morning 60% of them had shown reduction in their SAD symptoms
• 30% of them showed reductions if they received it during the Evening
• 5% showed reduction if they received the placebo treatment.

Conclusion: SAD is highly dependent on exogenous zeitgebers (levels of light) when it comes to the regulating of physiological and psychological activities within the biological rhythm.

Question 9

Explain how research into SAD and infradian rhythms has had positive real life application

Answer 9

-SAD research has provided us with the adverse effects the disorder has on people, such as prolonged periods of fatigue and low mood which are symptoms of depression. It has also allowed us to identify what are the causes of these symptoms which are day light and excess melatonin secretion. Therefore treatments such as phototherapy which involve a strong light bulb to suppress melatonin secretion from the pineal gland have been developed and have been found very effective. This has reduced the symptoms of depression in individuals who have SAD which supports the role of research into Infradian rhythms.