Infradian and Ultradian Rhythms Flashcards
Infradian Rhythms
Biological rhythms which are longer than 24 hours, for example the menstrual cycle which occurs every 30 days.
Menstrual cycle
-Example of an infradian rhythm which occurs every 30 days, the endocrine system acts as the endogenous pacemaker regulating and faciliating the biological changes each month by releasing hormones
-Exogenous zietgibers are also thought to play a role in regulating the menstrual cycle
Exogenous Zietgibers in the menstrual cycle
Pheremones from other women and light
+Research support for the role of light in menstrual cycle-Reinberg
-Found that a woman who spent 3 months in a cave with only a small light had a reduced menstrual cycle to 25 days-light regulates the menstrual cycle to 30 days
+Research for the role of pheremones, stern
Found that if women smelled pheremones from the armpit of a woman at the end of her menstrual cycle she would experience a shorter cycle but if she smelled pheremones from the armpit of a women at the start of her cycle it would be longer-pheremones from other women act as an EZ regulating the length of the cycle
Problems with menstrual research-Low control
-Confounding variables, multiple factors can change the length of the menstrural cycle, things like changes to diet quality due to being in a cave, stress or depression or anxiety due to the cave may cause an abnormal menstrual cycle, not light-cannot establish cause and effect that light is the result of the reduced cycle thus cannot show light is an EZ-cant establish cause and effect-low internal validity.
Who conducted research showing female pheremones act as an exogenous zeitgiber influencing menstrual cycle length
Stern et al
Ultradian Rhythms
Rhythms which occur in a time frame less than 24 hours, e.g the stages of sleep occur every 90 minutes
Stages of sleep
-Characterised by cyclical changes in brainwave activity
N1- Brain activity begins to lower-less awareness-body begins to relax
N2- Body begins to futher relax, short bursts of brain activity on EEG
N3- Delta waves begin to be produced, brainwaves are significantly reduced
REM sleep: Complete relaxation, irregular breathing, dreams occur in this state
KIETMAN
Used EEGS in a laboratory environment to study the stages of sleep-found we pass through 4 stages of sleep characterised by changing brainwaves every night, and that dreams occur during the REM stage
Kietman-objectivity
+Supported by Kietman-used EEGS to show we pass through stages of sleep-objective measure of brainwave activity-scientific-valid and suggests stages of sleep are a biological ultradian rhythm
-Kietman-Insight
-Lacks insight, cant tell us about the controlling mechanisms behind ultradian rhythms just that they do occur-simplistic
