Infradian and Ultradian Rhythms Flashcards
Biopsychology
What is an Infradian Rhythm
Biological rhythm with a frequency of less than one cycle in 24 hours.
Menstrual Cycle
Regualted by hormonal changes, lasting around 28 days.
Rising levels of oestrogen prompt egg release (ovulation), while progesterone supports the uterine lining for potential pregnancy.
If no fertilisation, hormone levels drop and lining is shed as menstruation.
Research on Menstrual Synchrony
Cycles may be influenced by exogenous cues like pheromones.
McClintock’s Study (1971): Examined menstrual synchrony in women living together and found cycles tended to align.
McClintock’s Study Process and Results
29 women with irregular cycles provide pheromone samples at different stages.
Sample is applied to other women’s upper lips, caused shifts in menstrual cycles, suggesting a biological influence.
68% said changes aligned with odour donor.
Seasonal Affective Disorder (SAD)
Infradian rhythm disorder where depressive episodes occur seasonally, typically in winter.
Characteristics: Increased Lethargy, low mood, craving for carbohydrates.
Linked to melatonin production, which increases in response to darkness/affects serotonin.
Common treatment is light therapy.
What are Ultradian Rhythms
Biological cycles lasting less than 24 hours.
Stages of Sleep 1 and 2
Light sleep/Sleep Escalator
Brainwave Activity - Slows down from alpha to theta waves as sleep deepens.
Characteristics - Person can be easily woken, relaxation of body increases.
Stages of Sleep 3 and 4
Deep Sleep/Slow-wave Sleep
Brainwave activity - Dominated by slow, high-amplitude delta waves.
Characteristics - Very difficult to wake someone; critical for physical restoration.
Stages of Sleep 5
Rapid Eye Movement Sleep (REM)
Brainwave activity - Brain activity increases significantly, resembling an awake state.
Characteristics - Body is paralysed to prevent acting out dreams, REM occurs.
Associated with Dreaming.
