60030
Description
Mind Map by becky.waine, updated more than 1 year ago
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Created by becky.waine
about 11 years ago
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Sleep and Dreaming
- Rhythms of waking
and sleeping
- EARLY IDEA was that
wake and sleep must
depend on something
outside the body such as
light
- HOWEVER
Richter
(1922)
suggested
that the body
generates
own activity /
inacitivity
- HOWEVER
Richter
(1922)
suggested
that the body
generates
own activity /
inacitivity
- Mechanisms of the biological clock.
Richter (1967) suggested we have a
biological clock. our cycles remain
stable despite changes in food, water,
xray
- Suprachiasmatic
nucleus (SCN)
- the SCN provides the
main control of the
circadian rhythms for
sleep and body temp.
after damage the
bodies rhythms
become erratic.
- the SCN is part of the hypothalamus,
located just above the optic chiasm.
light resets the SCN via the
retinohypothalmic path
- the path comes from a special
population of ganglion cells that have
their own photopigment, melanopsin.
which respond directly to light no
rods/cone
- the path comes from a special
population of ganglion cells that have
their own photopigment, melanopsin.
which respond directly to light no
rods/cone
- RALPH et al., (1988)
found in rats that a
mutation caused a
20hr rhythm and
when transplanted
into another rat, they
take on this rhythm.
donor based
- even a single
isolated SCN cell
can maintain a
circadian rhythm.
- even blind people with
damage to rods and cones
have enough input to
melanopsin containing
ganglion cells to have their
cycle set to local sunlight
- the SCN provides the
main control of the
circadian rhythms for
sleep and body temp.
after damage the
bodies rhythms
become erratic.
- Freedman et al. (1999)
even blind mole rats with
no eye muscles or lens,
or response to bright
light can set their cycle
to sunlight
- two types of genes
responsible for
generating circadian
rhythm, PERiod &
TIMeless.
- when per and tim are high
they interact with a protein
and induce sleepiness, when
low = wakefulness.
- when per and tim are high
they interact with a protein
and induce sleepiness, when
low = wakefulness.
- two types of genes
responsible for
generating circadian
rhythm, PERiod &
TIMeless.
- the SCN regulates sleep / wake
by controlling activity levels in
pineal gland. this gland releases
melatonin, which influences
rhythms
- Melatonin pills work 2-3 hours before bed and
are useful for travel across timezones.
- Melatonin pills work 2-3 hours before bed and
are useful for travel across timezones.
- Suprachiasmatic
nucleus (SCN)
- ENDOGENOUS INFLUENCES
(inside the body)
- endogenous circannual
rhythm - internal mechanisms
on a yearly cycle
- endogenous circadian rhythms
- on a 24 hour internal cycle
- light from the sun makes
you feel less sleepy. in an
unchanging environment
(constant darkness) the
self-generated cycle might
be longer than 24 hours
- Kelly et al., 1999. people in submarines cut off
from sunlight and have 18 hour schedules but
they still retain rhythms of alertness at about
24.3 hrs
- Kelly et al., 1999. people in submarines cut off
from sunlight and have 18 hour schedules but
they still retain rhythms of alertness at about
24.3 hrs
- circadian rhythms for
eating, drinking,
urination, secretion of
hormones, sensitivity to
drugs etc... also for mood
- circadian rhythms differ among
people, e.g. morning and
evening people. (Taillard et al,
2003)
- people will find their way
back to a 24 hour cycle
even if their environment
differs from that
- circadian rhythms differ among
people, e.g. morning and
evening people. (Taillard et al,
2003)
- Siffre (1975) spent 6 months
in a cave and found that
humans hold a 25 hour cycle
when no external cues
- endogenous circannual
rhythm - internal mechanisms
on a yearly cycle
- EXOGENOUS INFLUENCES (outside the body)
- circadian rhythms can
persist without light
although light is critical
for resetting them.
- without something to reset the
rhythm, it could gradually drift
from the correct time. stimuli
that resets the rhythm called a
ZEITGEBER (time giver)
- light is the
dominant Zietgeber
although others
include any arousal,
exercise, meals,
temperature. social
stimuli are weak
zeitgebers.
- Zeitgeber
for marine
animals are
the tides
- light is the
dominant Zietgeber
although others
include any arousal,
exercise, meals,
temperature. social
stimuli are weak
zeitgebers.
- without something to reset the
rhythm, it could gradually drift
from the correct time. stimuli
that resets the rhythm called a
ZEITGEBER (time giver)
- external stimuli affect
our circadian rhythms,
as when the change
to daylight saving
occurs, people
remain ill-rested and
inefficient for days
after
- Roenneberg et
al., 2007. study on
Germany's
circadian
rhythms. the sun
time at the east
differs half an
hour to the west.
- They found that
people on the
eastern edge
have a sleep
midpoint 30
minutes earlier
than people on
the west.
- They found that
people on the
eastern edge
have a sleep
midpoint 30
minutes earlier
than people on
the west.
- blind people set their
rhythms by noise, temp,
meals etc. their rhythms
are a little longer than 24
hours. cycle not with clock,
experience insommnia
- Jet lag majorly disrupts
circadian rhythms.
easier to travel west than
east
- due to easier to adapt to
phase-delay (stay awake later,
rise later) than to
phase-advance (sleep earlier,
rise earlier)
- Cho (2001) found
adapting caused stress
and elevated hormone
cortisol which impaired
memory in flight
attendants.
- Cho (2001) found
adapting caused stress
and elevated hormone
cortisol which impaired
memory in flight
attendants.
- due to easier to adapt to
phase-delay (stay awake later,
rise later) than to
phase-advance (sleep earlier,
rise earlier)
- Shift workers find it hard to
adapt even after many
years. night-time workers
have more accidents than
daytime.
- circadian rhythms can
persist without light
although light is critical
for resetting them.
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