circadian rhythms intro Flashcards
Rhythms in the envrionment rely on_____
Sun - light exposure, seasons
Moon - tides, phases of the mood
Earth
3 reasons WHY we have rhythms
1) organisation - internally into epochs
2) Anticipation - of events, planning energy use
3) Seasonality - animals knowing when to mate
What spurred the first experiments with rhythms in 1726 where De Mairan?
He isolated plants from light and observed that they still regularly opened/closed
List some properties of the body clock
1) Endogenous
2) is ‘free running’ - can be managed by itself when cues are removed
3) is settable - can be entrained/synced with environment, if then left in darkness, will shift back towards natural period
4) is innate - genetic
5) is NOT temperature dependent (external)
Phase refers to ________
a point on a circle that represents a 24h cycle
Phase shift _______
rapid shift in phase due to ENVIRONMENTAL change i.e delaying/advancing phase with light exposure
Phase angle difference / angle of entrainment ________
difference between INTERNAL vs EXTERNAL time i.e. hours diff between DLMO/sleep time
Tau is __________
is the LENGTH of an endogenous rhythm // PERIODof a rhythm when all external cues are removed
Zeitgeber is _________
Something that changes INTERNAL clock i.e. light, caffeine, meds etc., = agent changing phase. represented by ‘t’
Zeitgeber time is __________
refers to ‘outer’ time
Subjective day/night refers to__________
when taking away enviro cues, nocturnal animal will still have sleep/wake cycles = when active, is its subj night (even there are no light cues to tell it so)
Compare circadian time vs zeitgeber time
CT - ‘inner’ day - phase
ZT - ‘outer’ day’ = time according to external cues i.e. light
After effects refer to_________
Adaptation to entrainment
Light pulse in the early evening will make your phase _______ the next day
DELAYED - will go to bed later = next day go to bed later
Light pulse in the early morning will make your phase _______ the next day
ADVANCED - start your CT earlier for the day, go to bed earlier too
The Phase response curve states we are
_______ to light during the day
unresponsive to light in the day
We are more likely to have regular START to our day than ends to our day
T/F
True - we depend on DAWN much more than dusk, stay up late with artificial lighting
Which population has the closest t approaching 24?
Elderly
if we have different free running rhythms, how does the same light cycle produce entrainment in us all
though we all run on different CT, and have the same sunlight exposure, it produces DIFFERENT entrainment in all of us i.e. delays phase for me but advances for ____
How is daily entrainment achieved?
daily phase delays/advances + daily ZT
PRC dictates that light in the first half of the night will cause ______ and _______in the second half of the night
DELAY the next day; ADVANCE the next day
Why is the prc unresponsive to light during day time?
Because light exposure during the day does not advance/delay person’s phase nothing happens
Which sex has the shorter phase?
WOMEN - more likely to be morning types bc have 6min shorter Tau (period) on avg, DLMO occurs before men, advanced phase compared to men
Why are women more likely to have insomnia?
more early morning disturbances bc core body temp is LOWEST earlier in the morning (strongest signal for sleep) = more wake ups in morning
