Infradian And Ultradian Rhythms

Question 1

Longer than 24 hours

Answer 1

Infradian

Question 2

Less than 24 hours

Answer 2

Ultradian

Question 3

Menstrual cycle AO1

Answer 3

• The female menstrual cycle, an example of an infradian rhythm, is governed by monthly changes in hormone levels which regulate ovulation.
• The cycle refers to the time between the first day of a woman’s period, when the womb lining is shed, to the day before her next period. The typical cycle takes approximately 28 days to complete (though anywhere between 24 and 35 days is generally considered normal).
• During each cycle, rising levels of the hormone oestrogen cause the ovary to develop an egg and release it (ovulation).
• After ovulation, the hormone progesterone helps the womb lining to grow thicker, readying the womb for pregnancy.
• If pregnancy does not occur, the egg is absorbed into the body, the womb lining comes away and leaves the body (the menstrual flow).

Question 4

SAD AO1

Answer 4

• Seasonal affective disorder (SAD) is a depressive disorder which has a seasonal pattern of onset, and is described and diagnosed as a mental disorder in DSM-5.
• As with other forms of depression, the main symptoms of SAD are persistent low mood alongside a general lack of activity and interest in life.
• SAD is often referred to as the winter blues as the symptoms are triggered during the winter months when the number of daylight hours becomes shorter.
• Psychologists have hypothesised that the hormone melatonin is implicated in the cause of
  SAD. During the night, the pineal gland secretes melatonin until dawn when there is an increase in light. During winter, the lack of light in the morning means this secretion srocessin in the brain - a chemical that has been linked to the onset of depressive symptoms.

Question 5

Stages of sleep AO1

Answer 5

• sleep cycle is an Ultradian Rhythm
• psychologist have identified 5 distinct stages of sleep that altogether span approximately 90 (cycle continues throughout the course of the night), each of the stages is characterized by a different level of brainwave activity which can be monitored using an EEG
• stages 1 and 2 are light sleep where a person may easily be woken. In stage 1 brain waves alpha waves and have a high frequency and have a short amplitude. In stage 2 the alpaca waved continue but there are occasional random changes in tree pattern called sleep spindles
• stages 3 and 4 is called deep sleep or slow waves sleep. The brain waved are delta waves.
• in stage 5 it is difficult to wake someone. The body is paralyzed yet brain activity closely resembles that of the awake brain. During this time the brain produces theta waves and the eyes occasionally move around, therefore stage 5 is sometimes called rapid eve movement sleep.
• dreams are most often experienced during REM but may also occur in deep sleep

Question 6

McClintock research?

Answer 6

• Martha McClintock observed synchronisation of menstrual cycles amongst her university friends
  
  • She asked 135 college girls living in dorms to recall their period start dates at three times during the academic year
  • Close-friend groups period were an average of 6.3 days apart in October decreasing to 4.6 days apart in April (later in the academic near)
  • Attributed to pheromones acting as external Zeitgeber

Question 7

Stern and McClintock research?

Answer 7

• Aim: to investigate influence of other women’s pheromones on the menstrual cycle
  
  • Procedure: 29 women with a history if irregular periods. 9 of these women provided pheromone samples from different cycle stages by wearing cotton pad under armpit for 8 hours. On day 1 the other 20 women smelled the pads from day 1 of the other women’s cycle, on day 2 smelled pads from day 2…
  • Findings: 68% of the 20 women experienced cycle changes in line with the ‘donor’
  • Conclusion: suggest menstrual cycles are influenced by other women’s pheromones acting as exogenous zeitgebers

Question 8

AO3 serotonin SAD

Answer 8

• Lambert et al. 2002 Found that serotonin production was directly related to sunlight, rising rapidly with increased luminosity.Also found that blood levels of serotonin metabolite (5-HIAA*) are lowest in winter suggesting low serotonin turnover.
• Low levels of serotonin have been linked to depression.
• This suggeststhat brain serotonin levels may underlie seasonal mood changes and SAD

Question 9

AO3 SAD practical applications

Answer 9

• Bright-light Therapy (BLT) has been used effectively to treat SAD (Anderson et al. 2009; Strong et al. 2009)
• BLT has been demonstrated as an effective, non-pharmacological treatment for both seasonal and non-seasonal depression

Question 10

AO3 REM and dreaming?

Answer 10

• Monitored sleep patterns of 9 adults by EEG. Controlled for caffeine & alcohol
• Found REM activity highly correlated to dreaming – Ps woken during REM gave highly vivid descriptions.
• Small sample size, but frequent replication of findings

Question 11

AO3 sleep stages generalise

Answer 11

• There is significant variation between individuals and sleep research
• Many have large differences in Stage 3 and Stage 4 (deep sleep)
• These differences are likely due to genetics
• Makes it impossible to generalise SLEEP STAGES

Question 12

Menstrual cycle research AO3 (4 points)

Answer 12

• Small sample sizes, self report methods and poor or incorrect statistical analysis (under-estimating chance) suggest the experimental validity is poor.
• Previous research found no such synchrony (e.g. Trevathan et al 1993)
• Evolutionary theory would suggest menstrual synchronization is not an adaptive strategy.
• Research with Dogon tribeswomen (Mali), who live in close proximity but are segregated to a specific hut when menstruating (negating the need for interview) found no synchrony (Strassman 1997).