Section 6 : Biopsychology - Biological Rhythms Flashcards
what are the three types biological rhythms
- Circadian Rhythms
- Infradian Rhythms
- Ultradian Rhythms
what are circadian rhythms
cycles that generally occur once every 24 hours e.g. sleep wake
what are infradian rhythms
cycles that occur less than once a day e.g. menstrual cycle
what are ultradian rhythms
cycles that occur more than once every 24 hours e.g. in the sleep cycle we have several repeating stages of light and deep sleep
what did sabbagh and barnard 1984 find
when women live together their menstrual cycle may synchronise, not clear why but could be due to pheromones
how are the timings of these biological rhythms determined
by factors inside and outside our bodies
what is the SCN
the suprachiasmatic nucleus, in the hypothalamus which acts as an internal clock to keep the body on a 24hr sleep wake cycle
what are endogenous pacemakers
biological structures and mechanisms that set the rhythms within the body such as the SCN in the hypothalamus
what is the SCN sensitive to
the SCN is sensitive to light and regulates the pineal gland which secretes melatonin. when there is less light more melatonin is produced and the other way around.
what are exogenous zeitgebers
influences outside the body that act like a prompt why may trigger a biological rhythm
what is the most important zeitgeber
light
what was siffre 1975
michel siffre spent six months in a cave. no clocks or natural light as zeitgebers. as a result his sleep wake cycle extended from 24hrs to a 25-30hr cycle. therefore seemed that natural light is needed to fine tune our normal 24hr cycle
what did penegelly and fisher find
that squirrels will hibernate even when kept in a lab conditions very different from their natural environment. this shows that in some cases endogenous factors may completely determine a cycle
what other factors can affect biological rhythms
- cultural factors e.g. Eskimos live in permanent night or day time and can maintain regular sleep cycles
- individual factors e.g. Aschoff and Wever found that some ppl isolated from daylight maintained daily sleep cycles but other members displaye their own extreme idiosyncrasies
what happens if u disrupt biological rhythms
negative effects e.g. slower reaction time, impairing problem solving skills, limiting ability to concentrate. changes such as light levels in winter and summer dont negative effects tho
Does jet lag have an effect in biological rhythms
Yes, you would be out of sync with the local timing as you would be waking up and falling asleep earlier.
What did Wegman et al find
That travelling east to west seems easier to adapt than travelling west to east
What did Schwartz et al find
Found that baseball teams from the east coast of USA got better results travelling to play in the west teams than teams based in the west when travelling to play in the east
Did shift work disrupt people’s sleep cycle
Yes
What was Czeisler et al 1982
- studied factory workers who shift patterns appeared to cause sleep and health problems
- the researchers recommended 21-day shifts (allowing more time for workers to adapt) and changing shifts forwards in time (phase delay).
- after implementing the changes productivity and job satisfaction increased
What are the limitations of research on biological rhythms
- findings from animal studies can’t accurately be generalised (humans have greater adaptability)
- studies of deprived humans of natural light allowed artificial light; reduces validity of studies as the artificial light can give benefits of the natural light
- studies into individual differences need further studies
- if we understand what causes problems linked to jet lag and shift work we can minimise and avoid work place accidents.
Why does there need to be more research into individual differences in the affect of rhythms
Some people are more alert early in the day and other later on, and the speed with which we adapt to disruption vary. It’s difficult to determine whether a person’s lifestyle is a cause or effect of their biological rhythms
