Ultradian and Infradian rhythms Flashcards
Define infradian rhythms?
Biological cycles that last longer than a day 24hrs
Examples of infradian rhythms
E.g migration patterns, flowering, menstrual cycle, SAD
Define ultradian rhythms
Biological cycles span a period less than one day.
Ultradian rhythm examples
E.g sleep/wake cycle
Examples of infraradian weekly rhythms
- Lower testosterone levels peak at weekend
- Lower frequency of births at the weekend
What dictates the menstrual cycle?
Dictated by the SCN and endocrine system (pituitary gland releases FSH/LH to stimulate ovulation)
Menstrual cycle
- Dictated by the SCN and endocrine system (pituitary gland releases FSH/LH to stimulate ovulation)
- Ovulation occurs halfway through the cycle when oestrogen levels peak
- After ovulation, progesterone levels ^ to prepare implantation of embryo in the uterus
How long is menstrual cycle on average?
Cycle is reported 28 days on average
What does refinetti report on infradian rhythm
(Refinetti reports 23-36 days)
What is an annual rhythm example
Annual rhythm example SAD ( seasonal affective disorder)
Seasonal affective disorder explanation
Research suggests seasonal mood variation in humans
* Some people become more depressed in winter months
- Winter months → lack of light results in longer melatonin secretion affecting serotonin
During the winter more heart attacks occur and more deaths occur in january
Russel study
Russel - daily sweat samples collected and rubbed onto upper lips of other women’s - cycles came synchronised by ‘odur donut’
Suggesting synchronisation can be affected by pheromones that have an effect on people close by rather than the individual producing them
whats an example of the ultradian rhythm?
sleep cycle
What does REM and NREM mean?
REM - rapid eye movement
NREM - non-rapid eye movement
how long is the sleep cycle on average?
The human sleep stage 1-4 involves a 90-100 minutes of REM (rapid eye movement) and NREM (non-rapid eye movement) sleep.
What can be used to monitor sleep cycles?
EEGs can be used to monitor these patterns
How many stages in the sleep cycle are there?
5 stages
stage one
Light sleep»_space;
Muscle activity slows down
Stage 2
Breathing and HR slows
Stage 3
Deep sleep begins»_space;>
Begins to generate slow delta waves
Stage 4
Very deep sleep»_space;
* Rhythmic breathing
* Limited muscle activity
* Brain produces delta waves
stage 5
REM»
* Brainwaves speed up
* Dreaming occurs
Who determined BRAC cycle?
Kleitman
What does kleitman mean by the BRAC cycle
suggests this 90 minute cycle actually happens all day
- Difference is during the day rather than moving through sleep stages we move through stages of alertness into stage of hunger/fatigue every 90 minutes
**
Suggests this is evident in people’s mid morning coffee at 10:30 which breaks the morning into 90 min intervals from 9-noon**
Case study - Tripp
- stayed awake for 8.5 days for charity
Experienced mood swings, body temp drop, hallucinations, paranoia → if cycle is disrupted can have serious consequences
Gardener - case study
stayed awake for 11 days
Suffered little symptoms of nausea but later experienced suffer extreme insomnia
Strengths - rhythms
- Research support for BRAC - UR
Ericsson studied a group of elite violinists → found the practice sessions were no more 90 mins at a time, and place systematically throughout the day , included with naps
The more able, the more naps
Consistent with the claim of 90 minute fatigue, providing real world application
Additionally, was found within musicians, athletes ,chess and writers → more generalizable
Limitations
- Individual differences in sleep - UR
Usually attributed to differences in non biological factors (EZS)
HOWEVER, Tucker study - sleep in strict Laboratory
Researchers assessed sleep duration, type to fall asleep etc
They found a large ID in each which showed up consistently across 8 nights.
As the environment was tightly controlled means the ID were not driven by circumstance - partial support as is still partly biologically determined
- Menstrual cycle - role of (EZs) RUSSEL et al
Is usually governed by EPs by release of hormones
When many women live together not taking oral contraceptives cycles sync - Study - daily sweat samples collected and rubbed onto upper lips of other women’s - cycles came synchronised by ‘odour donur’
Suggesting synchronisation can be affected by pheromones that have an effect on people close by rather than the individual producing them
Hormonal changes can be influenced so cycles can be influenced by external factors. - Belief in lunar rhythms - alternative
The belief in infradian rhythms based on the moon is still prevalent.
Midwives still believe more babies are born during full moon than a new moon
Erlis - surveys of workers in the mental health profession showed persistence in views the full moon can alter behaviour even after studies proved otherwise. - Validity and reliability of sleep patterns
Lab environment → modifying the research
Biologically or non-biological factors (temp,sleep hygiene)
Sleep patterns are biologically deterministic/reductionist saying all sleep the same cycles
as (temp,sleep hygiene) external factors contributed
sleep deprivation study how to evaluate them
- TRIPP → stayed awake for 8.5 days for charity → got hallucinations / Paranoia
- Garderner → teenager stayed awake for 11 days → only nausea but later life extreme insomnia
Studies both lend support to the idea sleep is vital for maintaining physical and mental health. However, highlight the effects of deprivation and sleep cycles may vary between individuals as the symptoms suffered where not identical
Explain the difference between infradian rhythms and ultradian rhythms - 2 marks
The difference between an infradian and ultradian rhythm is the duration of the cycle. An infradian rhythm is one that lasts longer than 24 hours whereas an ultradian rhythm lasts less than 24 hours.
