Circadian Rhythms Flashcards
circadian rhythms is
the biological cycle that lasts within the 24h, adapts the body to meet the demand of the day-night cycle
what does the circadiam rhythms dectates to us
when to be awake and when to be sleepy
when is the biggest urge to sleep
1-3am
2-4pm
sleep drive is controlled by…. and placed in….
Syperchaismatic nucleus (SCN)
in Hypothalamus
what input does it need to receive
light
internal circadia clock is
a free running (24-25h)
shift works an Jet leg
disrupts the clock, as it stops matching with the environment
tryingg to be active when the body wants to sleep
Photoentrainment
sychronising the inner clock with the environment
making the brain active when it’s light
and making it slow down when it`s dark
sleep urge (drive for alertness)
is a conscious or a psychological understanding of need for sleep
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sleep drive (sleep need)
is a biological need to sleep
circadian clock is controlled by
homeostasis
when we are awake for far too long homeostasis tells us we need to sleep
how the sleep-wake cycle happens in terms of hormones
light goes into retina
to SCN to pineal gland and it secretes Melatonin, which makes us sleepy
what is another example of Circadian rhythm
temperature
when our temperature is the lowest
4:30 am
when our temperature is the highest
6:00 pm
how is it connceted with sleep-wake cycle
low temerature when we feel sleepy prompting the body to sleep
and it is higher when we are trying to wake up, production of melatonin ceases, and body heats up
describe the temperature cycle
12:00-4:00 - going down
4:00-6:00 = the lowest
going up untill2:00 pm
2-4pm is a Postprandial dip
exercise can increase temperature
going up until 9pm increasing alertness, concentration
going down again as the melatonin being produced
where Melatonin is produced
pineal gland behind SCN
what melatonin does
makes the body sleepy
describe melatonin cycle
at 8pm strats to produce melatonin, as less light goes in,
at 3am - pick of melatonin
slowly goes down
around 6am it rrapidly goes down, and starts to wake the body up
Circadian rhythm
eval 1 top
a case study of Michel Siffre done as an evidence of Free-running clock
Circadian rhythm
eval 1 point
case study
he spent 61 day underground with no light and no clock. nothing that could serve as a exogenous zeitgebers. when he resurfaced, he found himself tinking it was 16 of September, while in reality it was 20th of August. which means 24-hour sleep-wake cycle was increased by the lack of external cues, making him believe one day was much longer than it was.
Circadian rhythm
eval 1 tail
cs
suggesting external cues do play an important role in 24 sleep wake cycle, as Michel`s clock has changed dramatically. however, it still went on running, meaning it doesnt fully dpend on light or external cues.
Circadian rhythm
eval 2 top
a weakness is the individual differnces that influence the circadian rhythms
Circadian rhythm
eval 2 point
found that the length of cycle can be very differnt - form 13 to 65h.
but not only that cycles can start at very differnt times: such we have an early birds - their cycle is shifted earlier than normal 24h cycle.
while for ight owls - the opposite
Circadian rhythm
eval 2 tail + double
this explains how differnt people are being awake at differnt times, and how produvtivity differs depending on it
even if it is a weakness to the case studies
it has a good ecological validity as it can be applied in real life and help people to reognise the way their sleep-wake cycle works, which will help them to know when they are the most alert and therefor the most productive, therefore improving their life.
Circadian rhythm
eval 3 top
research into circadian rhythm leads a real life application. Chronotherapuitics - which is the study of how timigs affect drug treatment
Circadian rhythm
eval 3 point
the specific time when a patient takes in the medicaion can play a significant role in the success of treatmnet.
such the right consentration released at the correct time - when the drug is most needed.
for example the risk of a heart attack is an early morning hours after awakening
Circadian rhythm
eval 3 tail
such with that research medics now can administrate the drug into the body foe example at 10 pm, but the actual release will be at the vulnurable hour e.g.6 am
therefore it was possible to improve the drug system
eval 4 top
a weakness of early studies is the methodology
Circadian rhythm
eval 4 point
as ppts were isolated form cues like clocks, radios, day light, it was believed that they are the onlt ones affecting sleep-wake cycle, however, they weren’t isolated from artificial light, as it was thought it will not influence
Circadian rhythm
eval 4 tail
however,later studies showed that it is possible using artificial light to alter the rhythm down to 22 and up to 28h
suggesting, the research was confound by the presence of artificial light
