Rhythms Flashcards
(9 cards)
Biological rhythms
Cyclical changes in physiological systems - adapted because environments have cyclical changes
Circadian rhythm
any cycle landing 24 hours - all types of organism have some bio representation of 24hr day - optimise based on physiology and behaviour to meet demands
Driver by suprachiasmatic nuclei (SCN) in hypothalamus - pacemakers constantly resets so bodies synchronise with outside world - natural light inputs to this system to calibrate SCN by photoentrainment
Sleep wake cycle
Light and darkness e externally signal when to sleep and wake up - but rhythm dips and rise at different points of day so strongest sleep drives during 2-4am and 1-3pm
Most melatonin from pineal gland during darkness (light inhibits production) which induces sleep
Homeostasis control - awake for long time then homeostasis tells us we need to sleep as lots of energy has been used - increases gradually and max at evening
Keeps awake as long as daylight and prompts to sleep upon darkness - internal rhythm will maintain 24-25hr cycle though
Circadian Rhythms eval
+ Chronotherapeutics - optimises time that meds are taken e.g risk of heart attack greatest upon waking around past 6am so drugs designed to take at night but release after 6am
+ Important to understand as essential to survive
- Research doesn’t account for artificial light but study has shown altering artificial light changes cycle length to 22-28hrs
- Individual differences - between 13-165 hrs, also differences in when rhythms peak - ‘morning’ people vs ‘evening people’
- People in arctic regions have somewhat normal sleeping patterns despite prolonged light exposure so EZ of light has little impact
+ Siffre locked himself in a cave for 3 months, for a month sleep was normal but long term had some changes until returning to normal again near the end - mixed impacts
Ultradian vs Infradian Rhythms
Ultradian Span period of less than 24 hours
Infradian is more than 24 hrs
Sleep stages
Ultradian rhythms - NREM 4 stages then REM sleep (non rapid or rapid eye movement) - analysed using eeg patterns
light sleep + activity slow (will say awake if awoken) , then breathing and heart slow, then deep sleep begin, then very deep sleep, then rapid eye movement with dreaming
Kleitman referred to as Basic Rest Activity Cycle which continued throughout day - state of alertness to fatigue - e.g can focus for 90 mins until resources run out so fatigue and hunger/ concentration loss
Ultradian Rhythms eval
+ Elitist violinists studied - they limited practice sessions to 90 mins and often napped to recover, better violinists napped more - similar patterns with athletes, writers etc fitting with BRAC
- Individual differences - maybe biological determinism - participants stayed in lab for 11 days and studied for sleep duration, time taken to fall asleep and stage time - differences in all characteristics
Menstrual cycle
Infradian rhythm - about a month but individual differences of 23-38 but average 28 days. Regulated by hormones e.g ovulation when oestrogen peaks and progesterone either decreases or stays high to allow implantation, or FSH which helps eggs mature
Infradian Rhythms eval
