Infradian & Ultradian Rhythms

Question 1

Menstrual Cycle

Answer 1

• Governed by monthly changes in hormone levels which regulate ovulation
• Cycle = Typically about 28 days although some have a 23 and/or 36-day cycle (Refinetti 2006)
• Rising levels of oestrogen cause the ovary to develop an egg and release it (ovulation), which occurs roughly halfway through the menstrual cycle, when oestrogen levels peak and usually lasts for 16-32hrs
• The womb lining grows thicker, ready for pregnancy – if the women does not get pregnant, then the egg is absorbed into the body and the womb lining leaves the body
• Menstrual cycle is an endogenous system – evidence suggests that it is influenced by exogenous factors such as cycles of other women

Question 2

Russel et al (1980)

Answer 2

• When women live together/spend long periods of time with each other, the menstrual cycles tend to synchronise

Question 3

Penton-Voak et al (1999)

Answer 3

• Found that human mate choice varies across the cycle
• Women preferred ‘slightly feminised’ male faces when picking a partner for a long-term relationship
• When in the ovulation phase, women showed a preference for ‘masculine faces’

Question 4

McClintock Research Study

Answer 4

• 29 women with a history of irregular periods
• Samples of pheromones were gathered from 9 of the women at different stages of their periods with a cotton wool pads placed on their armpits
• The cotton wool pads were worn for 8 hours to ensure pheromones were picked up – pads were then treated and frozen and to be rubbed on the upper lip of other participants
• On day one, pads from the start of the menstrual cycle were applied to all 20 women; on day 2, they were all given a pad from the second day and so on
• 68% synced to their odour donor

Question 5

SAD (Seasonal Affective Disorder)

Answer 5

• Depressive mental disorder which has a seasonal pattern of sadness – symptoms (persistent low mood, lack of activity and energy, etc) are triggered in the winter months due to a lack of daylight
• Melatonin is a hormone that can cause SAD – the pineal gland secretes melatonin during the night until dawn
• During the winter, the lack of light means that melatonin secretes for longer, which can mean that less serotonin is produced in the brain, leading to depressive symptoms

Question 6

Sleep Stages - Ultradian

Answer 6

1) Drowsiness (eyes move very slowly and muscle activity decreases)
2) Light sleep (eye movement stops, heart rate and breathing decrease)
3 & 4) Deep Sleep (no eye movements, no muscle activity)
5) REM (rapid eye movements, heart rate and breathing increase, dreams)