REM - dream time,
brain activity similar
to consciousness,
but body paralysed.
Paradoxical state
~ 90 minutes.
More REM
later in night
Dement & Kleitman -
woken in REM normally
dreaming, however not
exclusive
Rest-activity cycle -
90 minute cycle
Freidman &
Fisher - 90
minute pattern
between eating
& drinking in
psychiatric
patients
Maintains metabolic processes
Infradian rhythms > 24 hours
The menstrual
cycle is an
example
Russell et al - pheromones can
sync menstrual cycles, collecting
sweat from one woman and rubbing
on the upper lips of other women
Can be controlled by
exogenous factors
PMS can be an effect
Dalton - PMS lead to
decreased academic
achievement, suicide
& crime
Schonberg et al -
women administered
higher shocks to a
learner a week
before menstruation
Nicholson - only 5%
women suffer PMS
Janiger -
PMS found in
all cultures
Seasonal affective disorder (SAD)
Melatonin & Serotonin levels possible
cause. More darkness - more melatonin,
causing less serotonin. Low serotonin
associated with depression
SAD & PMS
inevitable
behaviours.
Johnson - Woman acquitted
of murder due to severe PMS
Born et al - Able to will your
body into change. People told
to wake up earlier had higher
ACTH (stress hormone) levels
Not an infradian rhythm,
just disrupted circadian
rhythm from sleeping earlier
Phototherapy - treatment
using very strong light
Eastman et al -
32% increased
from placebo effect
Endogenous pacemakers
& exogenous zeitgebers
Endogenous pacemakers
SCN nerve cells
in hypothalamus
Gets light information
as it is just above the
optic chiasma. Info still
received when eyes
shut
Morgan - hamsters bred
with 20 hour circadian
rhythm. SCN removed
and transplanted. 20
hour cycle again shown
Animal research like this causes
permanent damage. Ethical
issues & cost benefit. Also how
generalisable is it to humans?
SCN split in each hemisphere
Ventral SCN -
easily reset by
external cues
Desynchronisation caused when ventral
and dorsal parts are out of phase
Dorsal SCN -
less affected
by light
Pineal gland produces
melatonin which inhibits
brain mechanisms for
wakefulness
DeCoursey et al - provided
evolutionary advantage,
Chipmunks without functioning
SCN more likely to die. - Awake &
night, making noise attracting
predators
Exogenous zeitgebers
Light
Affects SCN and
peripheral oscillators
Contain
cryptochrome (CRY)
- sensitive to light
Campbell & Murphy - reset
circadian rhythms shining light on
the back of participants knees
Challenged idea of SIffre cave
study that light had no effect
Not
replicated
Stevens -
artificial light
world affects
hormone levels,
increased
cases of cancer
Blue light (in electronics &
energy saving bulbs) perfect
for resetting circadian rhythm.
Can set it an hour back
Social
cues
Davidson - mealtimes
reset heart & liver cells
Biological system control
adaptive advantage - difficult
to override when faulty
Temperature
Cold - signal for
reduced activity
Warm - time
for activity
(sleep-wake)
Buhr et al - temperature changes
from circadian clock. In turn this
regulates other circadian rhythms
Endogenous & Exogenous factors
work together to regulate rhythms.