circadian rhythms intro

Question 1

Rhythms in the envrionment rely on_____

Answer 1

Sun - light exposure, seasons
Moon - tides, phases of the mood
Earth

Question 2

3 reasons WHY we have rhythms

Answer 2

1) organisation - internally into epochs
2) Anticipation - of events, planning energy use
3) Seasonality - animals knowing when to mate

Question 3

What spurred the first experiments with rhythms in 1726 where De Mairan?

Answer 3

He isolated plants from light and observed that they still regularly opened/closed

Question 4

List some properties of the body clock

Answer 4

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)

Question 5

Phase refers to ________

Answer 5

a point on a circle that represents a 24h cycle

Question 6

Phase shift _______

Answer 6

rapid shift in phase due to ENVIRONMENTAL change i.e delaying/advancing phase with light exposure

Question 7

Phase angle difference / angle of entrainment ________

Answer 7

difference between INTERNAL vs EXTERNAL time i.e. hours diff between DLMO/sleep time

Question 8

Tau is __________

Answer 8

is the LENGTH of an endogenous rhythm // PERIODof a rhythm when all external cues are removed

Question 9

Zeitgeber is _________

Answer 9

Something that changes INTERNAL clock i.e. light, caffeine, meds etc., = agent changing phase. represented by ‘t’

Question 10

Zeitgeber time is __________

Answer 10

refers to ‘outer’ time

Question 11

Subjective day/night refers to__________

Answer 11

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)

Question 12

Compare circadian time vs zeitgeber time

Answer 12

CT - ‘inner’ day - phase

ZT - ‘outer’ day’ = time according to external cues i.e. light

Question 13

After effects refer to_________

Answer 13

Adaptation to entrainment

Question 14

Light pulse in the early evening will make your phase _______ the next day

Answer 14

DELAYED - will go to bed later = next day go to bed later

Question 15

Light pulse in the early morning will make your phase _______ the next day

Answer 15

ADVANCED - start your CT earlier for the day, go to bed earlier too

Question 16

The Phase response curve states we are

_______ to light during the day

Answer 16

unresponsive to light in the day

Question 17

We are more likely to have regular START to our day than ends to our day
T/F

Answer 17

True - we depend on DAWN much more than dusk, stay up late with artificial lighting

Question 18

Which population has the closest t approaching 24?

Answer 18

Elderly

Question 19

if we have different free running rhythms, how does the same light cycle produce entrainment in us all

Answer 19

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 ____

Question 20

How is daily entrainment achieved?

Answer 20

daily phase delays/advances + daily ZT

Question 21

PRC dictates that light in the first half of the night will cause ______ and _______in the second half of the night

Answer 21

DELAY the next day; ADVANCE the next day

Question 22

Why is the prc unresponsive to light during day time?

Answer 22

Because light exposure during the day does not advance/delay person’s phase nothing happens

Question 23

Which sex has the shorter phase?

Answer 23

WOMEN - more likely to be morning types bc have 6min shorter Tau (period) on avg, DLMO occurs before men, advanced phase compared to men

Question 24

Why are women more likely to have insomnia?

Answer 24

more early morning disturbances bc core body temp is LOWEST earlier in the morning (strongest signal for sleep) = more wake ups in morning

Question 25

What is the consequence of having a drastically different timing from external day?

Answer 25

Shorter life span

Question 26

Nature can select for ________ factors

Answer 26

Tau/period

Sensitivity

Question 27

Why does phase angle matter?

Answer 27

It is an EXTERNAL representation of the difference between internal/ext rhythms, is naturally selected for.
Greater angle = more risk of disease, death