496658
Description
Mind Map by katieclarke0204, updated more than 1 year ago
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Created by katieclarke0204
over 10 years ago
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CIRCADIAN RHYTHMS
- LAST ABOUT 24 HOURS
- SLEEP WAKE CYCLE
- External Cues/
Exogenous
Zeitgebers
- Changes in daylight
- Knowing
what time of
the day it is
- Changes in daylight
- Internal Cues/
Endogenous Zeitgebers
- Free running, about
24-25 hours
- ASCHOFF AND WEAVER (1976) -
Placed Ps in WWII bunker in absence
of environmental/social time cues,
found most rhythms were between
24-25 hours even though some were
as long as 29. This shows
free-running cycle is 24-25 hours.
- ASCHOFF AND WEAVER (1976) -
Placed Ps in WWII bunker in absence
of environmental/social time cues,
found most rhythms were between
24-25 hours even though some were
as long as 29. This shows
free-running cycle is 24-25 hours.
- Free running, about
24-25 hours
- EVALUATION
- CZEISLER ET AL
(1999) - Altered rhythms
down to 22 hours and up
to 28 hours just using
dim lighting
- In early studies P's
weren't isolated
from artificial light as
it was thought to
have no effect on
the circadian rhythm
- CZEISLER ET AL (1999) - Found
that individual circadian cycles
can vary from 13 to 65 hours
- DUFFY ET AL (2000) -
Found that morning people
prefer to rise early (6am)
and go to bed early (10pm)
but evening people prefer
to wake and go to bed later
(10am and 1am)
- CZEISLER ET AL
(1999) - Altered rhythms
down to 22 hours and up
to 28 hours just using
dim lighting
- MICHAEL SIFFRE
- SIFFRE (1999) - His natural circadian rhythm settled
down to just over 24 hours but changed up to 48. But at
60 years old he was interested in the effects old age
had on biological rhythms, finding his internal clock now
ticked slower and his sleep patterns had changed
- SIFFRE (1962) - Spent 61 days
underground in the southern Alps and
resurfaced on the 17th September
believing the date was 20 August
- SIFFRE (1999) - His natural circadian rhythm settled
down to just over 24 hours but changed up to 48. But at
60 years old he was interested in the effects old age
had on biological rhythms, finding his internal clock now
ticked slower and his sleep patterns had changed
- External Cues/
Exogenous
Zeitgebers
- CORE BODY TEMPERATURE
- Lowest at about 4:30 am (36'c) and
highest at around 6.00pm (38'C)
- Slight dip after lunch as a
result of people having a siesta
- Temperature dip is a bi-daily rhythm which
is an example o an ultradian rhythm
- EVALUATION
- FOLKARD ET AL (1977) - Looked at learning abilities of 12/13
year olds who had a story read to them at either 9am or 3pm, found
the afternoon group (higher body temp) showed superior recall and
comprehension, retaining 8% more meaningful material
- GUPTA (1991) - Found performance
on IQ tests was best at 7pm when
compared with 9am or 2pm
- GIESBRECHT ET AL (1993) - Lowered body temp by placing
Ps in cold water and found cognitive performance decreased
- HORD AND THOMPSON (1983) - Tested
cognitive performance in a field rather than lab
setting and didn't find any correlation between
core body temp and cognitive performance
- WRIGHT ET AL (2002) -
Said higher body temp may
lead to increased
physiological arousal which
then leads to improved
cognitive performance
- FOLKARD ET AL (1977) - Looked at learning abilities of 12/13
year olds who had a story read to them at either 9am or 3pm, found
the afternoon group (higher body temp) showed superior recall and
comprehension, retaining 8% more meaningful material
- Lowest at about 4:30 am (36'c) and
highest at around 6.00pm (38'C)
- HORMONES
- Cortisol, a hormone produced
when we're stressed but also
related to making us alert when we
wake up is at its lowest at midnight
and peaks at 6am which explains
why if we awaken at 4am its hard
to think clearly as cortisol levels
are not high enough for alertness
- Melatonin (which induces
sleepiness) and growth
hormone also have clear
circadian rhythm and peak
around midnight
- Cortisol, a hormone produced
when we're stressed but also
related to making us alert when we
wake up is at its lowest at midnight
and peaks at 6am which explains
why if we awaken at 4am its hard
to think clearly as cortisol levels
are not high enough for alertness
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