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PSYC388 BIOLOGICAL RHYTHMS AND SLEEP > MODULE 5: NON-PHOTIC TRAINING IN HUMANS > Flashcards

MODULE 5: NON-PHOTIC TRAINING IN HUMANS Flashcards

1
Q

Aschoff and Wever’s WWII bunker experiment allowed for subjects to live in ___ isolation for weeks/months

A

isolation

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2
Q

what was confirmed in Aschoff and Wever’s WWII experiment? (2)

A

humans have true circadian rhythms that persist in constant conditions

appear to entrain to a daily LD

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3
Q

people who were entrained to a gong sound that reinforced the LD cycle provided evidence that.. (2)

A

humans are less sensitive to light as a time cue

social cues might be the primary zeitgeber

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4
Q

in subsequent experiments, allowed no access to the time of day nor contact with the outside.. using an overhead light as their light source what did experimenters expect?

A

that they would entrain to the overhead light

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5
Q

in subsequent experiments, allowed no access to the time of day nor contact with the outside.. using an overhead light as their light source what actually happened?

A

subjects free-ran with a tau >24h

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6
Q

Czeisler found that when subjects were allowed to use a reading lamp when the overhead lights were off each day that..

A

it gave subjects the potential to create their own LD cycle

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7
Q

after re-examination of the issue that human LD cycles are not sufficient enough to entrain.. Czeisler found that..

A

if an LD cycle was strictly enforced, subjects did entrain

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8
Q

previously discusses methods are barely used to investigate circadian rhythms, why? (2)

A

it takes weeks/months to test each subject

requires substantial subject commitment

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9
Q

what 2 main questions are typically being asked?

A

do humans free-run in constant conditions?

do humans entrain to LD?

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10
Q

what is the faster procedure to answer these questions?

A

the constant routine method

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11
Q

recall: briefly describe the constant routine method

A

subjects cannot get out of bed

are fed at regular intervals

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12
Q

what are the 2 benefits of using the constant routine method?

A

eliminates the masking effects of behaviour/LD transitions

allows repeated measures of core body temp/melatonin/cortisol

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13
Q

the removal of ___ effects and ____ sampling provides and accurate assessment of the ___&____ of the rhythms being measured

A

masking
frequent
phase & period

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14
Q

which rhythm is not affected by the sleep-wake cycle and is a product released by the pineal gland?

A

melatonin secretions

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15
Q

describe melatonin levels throughout the day

A

rises in the evening/prior to sleep onset

peaks in the middle of the night

falls in the morning

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16
Q

the secretion of melatonin is rapidly ___ by light

A

supressed

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17
Q

when using a constant routine method in dim light what are the rise/fall of melatonin in the evening/morning called?

A

evening: dim light melatonin onsets
morning: dim light melatonin offsets

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18
Q

describe the procedure when investigating if light can induce phase shifts in humans while using the constant routine method

A
  • subjects sleep 3 nights in the lab
  • undergo a 30h constant routine
  • sleep from 12-8pm
  • stay awake all night
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19
Q

during the staying up all night period: after how long is a light pulse introduced?

A

6h

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20
Q

after staying up all night, subjects will sleep again from 12-8pm where after they undergo..

A

the 2nd constant routine method for a full day

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21
Q

what 2 things are sampled and their peaks are compared during which part of the procedure?

A

melatonin
body temp

during the constant routine parts

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22
Q

when comparing the peaks of melatonin and body temp during the constant routine parts, it was found that..

A

light induced a large delay shift

midpoint of melatonin was phase delayed by 3.6h during the 2nd constant routine

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23
Q

is a phase response curve in humans the same shape as PRC in animals?

A

yes

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24
Q

light early in the subjective night causes a..

A

phase delay

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25
Q

light in the late subjective night causes a..

A

phase advance

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26
Q

when do we see the crossover from delays to advances?

A

at the body temperature minimum which is about 3 hours before a spontaneous wakeup

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27
Q

what is the deadzone? is this present in nocturnal animals?

A

a time that occurs in the middle of the subjective day

may be absent in nocturnal animals

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28
Q

introducing light before the minimum body temperature causes a..

A

phase delay

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29
Q

when do we see the crossover from advances to delays?

A

about 12h before or after the body temperature minimum

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30
Q

is there an extended period during the subjective day like the deadzone?

A

no

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31
Q

introducing light after the minimum body temp causes..

A

a phase advance

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32
Q

what subjects can be used when looking for non-photic regulation of circadian rhythms?

A

those who lack visual function

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33
Q

someone can be blind but still have ..

A

retinal photoreceptors that respond to light and can communicate the LD cycles to the brain

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34
Q

some people can have no conscious vision and are unable to discriminate light/dark BUT can show ___ responses to light exposure

A

neuroendocrine

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35
Q

neuroendocrine responses are still evident how?

A

measuring melatonin concentrations in the blood/saliva

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36
Q

describe the control of melatonin’s secretion

A

via the pineal gland under the control of the circadian clock

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37
Q

what are the 2 effects light has on melatonin?

A

entrains the circadian clock that consequently controls melatonin release

rapidly inhibits melatonin synthesis and release

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38
Q

when light inhibits melatonin synthesis and release, is that dependent or independent on the circadian clock?

A

indepedent

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39
Q

turning on a light in the middle of the night (sleeping) causes..

A

a suppression in melatonin synthesis and a rapid reduction of plasma melatonin concentration

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40
Q

how is light information communicated to the pineal gland and how is the circadian clock in the hypothalamus entrained?

A

via photoreceptors in the retina

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41
Q

how can we distinguish between a totally blind or just visually blind person?

A

the melatonin suppression response to light exposure

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42
Q

if a blind person still shows light-induced melatonin suppression they are ____ blind

A

visually

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43
Q

a positive melatonin suppression result means the person is …

A

not circadian blind

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44
Q

a negative melatonin suppression result means..

A

the person is circadian blind and they cannot entrain LD cycles

45
Q

what does DLMO stand for?

A

dim light melatonin onset

46
Q

what is DLMO?

A

the time when the level of melatonin reaches 25% of the maximum value that it can eventually exhibit

47
Q

using 2 blind individuals: they underwent a 2 day constant routine every 20-30 days where experimenters measured..

A

their melatonin rhythms and their DLMO

48
Q

using 2 blind individuals: they underwent a 2 day constant routine every 20-30 days: being exposed to light pulses allowed experimenters to determine if they retain ____

A

circadian photoreception

49
Q

the individual who did not show melatonin impression in response to light showed a __________ in their actogram

A

progressive shift of DLMO across their tests

50
Q

was the person who showed no melatonin suppression free-running despite the attempt to maintain a 24h sleep-wake cycle?

A

yes

51
Q

people who tend to be circadian blind typically report..

A

being unable to fall asleep or have trouble staying awake in the day

52
Q

the individual who did show melatonin suppression showed a _____ DLMO near their bedtime

A

rountinely

53
Q

the person who showed melatonin suppression showed ___ photic entrainment and can be distinguished as..

A

normal

visually blind

54
Q

melatonin as a ___ can entrain rhythms

A

drug

55
Q

____ melatonin can shift circadian rhythms

A

exogenous

56
Q

___ melatonin provides a measurement of rhythms

A

plasma

57
Q

___ melatonin has a circadian rhythm

A

endogenous

58
Q

what would someone intuitively think about blind people and non-photic cues?

A

they would be more sensitive to non-photic time cues

59
Q

blind people lacking photoreceptors normally ____ while maintaining a 24h work schedule does not allow non-photic stimuli to have much or any effect

A

free-running

60
Q

blind people might have more difficulty doing what?

A

entraining to 24h non-photic cues

61
Q

the circadian clock in blind people is 0.4h ___ than those in sighted people

A

slower

62
Q

describe the limit of/range to entrainment

A

PRC to light pulses show that circadian rhythms can only be shifted a small fraction of a single circadian cycle per cycle

63
Q

the period of a LD cycle must be within ___h of tau for LD to entrain the clock

A

1-3

64
Q

using a ___ zeitgeber causes ___ shifts and a smaller ___ of entrainment

A

weak

smaller

range

65
Q

non-photic ____ should be more effective for sighted people than the circadian blind

A

zeitgebers

66
Q

what is an important source of potential non-photic zeitgebers?

A

social interactions

67
Q

alarms, parents, breakfast, physical activity, or showers are all examples of non-photic sources that can cause..

A

internal/endocrine signals that can affect the circadian clock

68
Q

co-housing people in temporal isolation was done to see if..

A

sleep-wake and other rhythms remain synchronized as a group or if each person free-runs with different periodicities

69
Q

after 10 days of bright light and 10 days of dim light bedtimes became..

A

more variable

70
Q

what was observed from the co-housing temporal isolation experiment?

A

people can ignore social cues and follow their own circadian cycle

71
Q

after the co-housing temporal isolation experiment: what is there to be said about social synchrony?

A

might be mediated by light exposure and not by non-photic stimuli

72
Q

studies are done in the artic because..

A

it is continuously light for part of the summer

73
Q

in the artic studies: subjects were observed to ..

A

free-run independently of each other

74
Q

in the artic studies: starting off with gathering for communal meals led to what.. because of independent free-running

A

eventually eating different meals at the communal meal time

75
Q

when isolating potential non-photic zeitgebers, one needs ________

A

controlled lab experiments

76
Q

studies were done examining the effects of 1h of high-intensity exercise on _____

A

phase of melatonin secretion rhythm

77
Q

in the high-intensity exercise study: what method was used to measure the first couple of cycles following the exercise stimulus?

A

constant routine method

78
Q

in the high-intensity exercise study: what were the 4 circadian phases that exercise was scheduled at?

A

night
morning
afternoon
evening

79
Q

in the high-intensity exercise study: ____ shifts were observed and the direction was dependent on the ____ of the exercise

A

small

time

80
Q

in the high-intensity exercise study: when did advanced shifts occur?

A

following early evening exercise and only on the first day following the exercise

81
Q

in the high-intensity exercise study: when did delay shifts occur?

A

following exercise in the night or morning or afternoon

82
Q

in the high-intensity exercise study: why are the results not super convincing?

A

the shifts are small and the phase advances were only evident on day 1 after exercise

83
Q

describe the non-24h T-cycle paradigm

A
  • subjects live on a 23.66 day with or without 2 scheduled bouts of exercise during their daily wake time
  • t-cycle: period of the zeitgeber bring manipulated
  • wake period light levels are dim
84
Q

in the non-24h T-cycle paradigm: what days were melatonin rhythms measured /averaged?

A

days 1/8/14

85
Q

in the non-24h T-cycle paradigm: the no exercise group showed a __ in melatonin rhythm relative to their daily bedtime

A

delay

86
Q

in the non-24h T-cycle paradigm: the exercise group’s melatonin rhythm on day ___ was closer to its day 1 position

A

14

87
Q

in the non-24h T-cycle paradigm: the execise group’s results showed that..

A

exercise did help the clock advance

88
Q

in the non-24h T-cycle paradigm: what was the methodological weakness?

A

the light was dim and not the same as in DD thus exercise could potentially increase light input and be responsible for daily advances

89
Q

manipulation of _____ alone without scheduled exercise has little effect on circadian rhythm

A

sleep-wake timing

90
Q

describe the experiment of the independent sleep-wake effect

A

subjects kept in dim light and fed at 4 fixed mealtimes went to bed at 9pm each day and were kept awake until 11:30pm on the first night

subsequent nights: experimental group could sleep 20 mins earlier each day for 7 days

measured bodily melatonin and temperature during constant routines before and after the 7day sleep-wake schedule

91
Q

in the independent sleep-wake effect study: describe the experimental group’s results

A

melatonin and temperature rhythms did not advance but they fell asleep earlier

92
Q

in the independent sleep-wake effect study: describe the control group’s results

A

kept the 24h sleep schedule and showed a delay of their temp/melatonin levels

93
Q

in the independent sleep-wake effect study: which schedule prevented the clock from phase delaying?

A

experiemental

94
Q

can the sleep-wake cycle shift the clock?

A

yes but it is a weak zeitgeber

95
Q

___ is a model used to investigate the effects of meal timing

A

Ramadan

96
Q

in Ramadan: when is food eaten for one month each year?

A

after sunset

97
Q

why can nothing be concluded from Ramadan studies?

A

so many stimuli are changed simultaneously

98
Q

describe how lab studies concluded that a food being a zeitgeber in humans is rare

A

eating a big breakfast or dinner for 3 days phase advanced the body temp rhythm but not the DLMO

99
Q

the DLMO is a ____ circadian clock phase maker in humans

A

gold-standard

100
Q

if the DLMO did not shift, the ___ probably did not shift

A

circadian clock

101
Q

circadian clocks in ___ are influenced by non-photic stimuli but the observed effects are ___ in contrast to rodents

A

humans

weak

102
Q

social cues are ___ and likely mediated by ______

A

weak

exercise/arousal//feeding

103
Q

exercise bouts can _____ but are modest in size

A

induce shifts

104
Q

exercise in the night or early morning can cause..

A

small delay shifts

105
Q

exercise in the early evening can cause..

A

phase advance shifts

106
Q

daily exercise can facilitate entrainment to _____ sleep-wake cycles and ____ to shifted sleep-wake cycles

A

unusual

re-entrainment

107
Q

scheduled sleep-wake cycles have ___ effects when light exposure and ___ are controlled

A

weak

meal timing

108
Q

the available data on ___ is too sparse to make any meaningful conclusions

A

food

PSYC388 BIOLOGICAL RHYTHMS AND SLEEP (5 decks)

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