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Psychology of Light and Time > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

Chronobiology

A

The systematic scientific study of living timing processes in plants and animals.

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2
Q

Jean Jacques (1729)

A

Even without sunlight, his plants open their leaves by day and close them at night

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3
Q

Circadian Rhythm

A

Cycle of various metabolic, chemical, endocrine & behavioural processes, alternately through high and low activity phases with a periodicity of ~ 24 hrs.

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4
Q

Daily rhythms

A

Patterns of behaviour, physiology, and biochemical patterns in humans

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5
Q

Circadian regulation organizes crucial yet potentially conflicting processes. Therefore, it has to be:

A
  • Persistent (self-sustained) in the absence of environmental cues
  • Robust (in dynamic circumstances, buffered against inappropriate signals)
  • Entrainable but also able to free-run at periods slightly different than 24h
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6
Q

Actigraphy

A

the method of collecting data on activity and sleep-wake patterns

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7
Q

Free-running period

A

internal period without limitation

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8
Q

Lobban (1957) Spitsbergen Study

A

Study on Forced desynchronization of 27 hours. Found that:
- Urinary flows follows sleep-wake
- Potassium excretion follows 24-hour rhythm
- Differential influence of endogenous vs exogenous cues.

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9
Q

What pattern does Urinary flows follow?

A

Sleep-wake

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10
Q

What pattern does Potassium excretion follow?

A

Circadian Rhythm

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11
Q

Forced desynchronization

A

behavioural rhythm is desynchronised to the internal rhythm .

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12
Q

Circadian Time

A

subjective internal organism time. In free running conditions, its endogenous rhythm is not 24 hours

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13
Q

A circadian hour

A

FRP/24

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14
Q

CT0 / CT12

A
  • CT0 = subjective dawn
  • CT12 is subjective dusk
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15
Q

Endogenous rhythm

A

Rhythm that continues even in the absence of any external cues.

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16
Q

Exogenous rhythm

A

a rhythm that occurs only in response to external cues.

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17
Q

The circadian principle

A

The longer we are active, the shorter we sleep

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18
Q

The homeostatic principle

A

The longer (and more) we are active, the deeper we sleep

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19
Q

Self-reported fatigue does not increase linearly over the day, but in sine-wave form. How is this?

A

Increasing sleep pressure during the day is (initially) counteracted by increasing wake signal but towards the end of day, both processes strengthen each other, then at night, fast decreasing sleep drive is counteracted by low wake drive.

20
Q

What drives the Circadian process?

A

The Suprachiasmatic Nucleus

21
Q

What pattern does melatonin flows follow?

A

circadian rhythm

22
Q

What pattern does core body temperature flows follow?

A

circadian rhythm

24
Q

What pattern does subjective alertness flows follow?

A

circadian rhythm

25
Q

What is melatonin?

A

a hormone synthesized and secreted by the pineal gland, - Peaks during subjective night, enables good sleep (initiation and consolidation)

26
What is cortisol?
Stress hormone
27
SWS?
Slow-wave sleep
28
EEG?
electroencephalogram - measures electrical activity in the brain using small, metal discs (electrodes) attached to the scalp
29
Duration of sleep after deprivation
the longer we are awake, the shorter we sleep. But there is a pivot point, where more activity leads to more sleeping (homeostatic principle)
30
What did Daan et al., (1984) found?
- Process S represents sleep pressure. Sleep onset is triggered when S ap- proaches an upper threshold (H); - awakening occurs when S reaches a lower threshold (L). - S rises, but not linearly - Circadian process C represents Circadian wake drive
31
Borbely two process model (1982)
A conceptual framework for understanding the timing and structure of sleep/wake behaviour: - Homeostatic process S and endogenous circadian Process C
32
Conscious decisions & environmental conditions affect threshold H. How to increase H? and how decrease H?
- Increasing H: Choosing to stay awake Social stimulation - Decreasing H: Warmth Bedrest Darkness
33
Somnostat
thermostat for sleep.
34
Constant routine
constant wakefulness , constant conditions, position, food intake, etc
35
There are processes that don’t return to baseline after 24 hours, but DO show circadian dynamic after 24 hours; these are under homeostatic & circadian influence.
- Slow eye movements - Karolinska Sleepiness
36
Why don’t people produce more melatonin when they are more tired.
Because melatonin production follows a circadian rhythm, and therefore is not influenced by homeostatic processes.
37
What is SCN?
SUPRACHIASMATIC NUCLEI - Generates circadian rhythms in physiology and behaviour and synchronize them to local time.
38
Entrainment
process of optimal synchronization with the environment - Match the solar day, while maintaining an appropriate phase relation to it - Mediated by zeitgebers acting on the clock
39
What is PRC?
Phase Response Curve (PRC) = describes the effect of the same stimulus at different circadian phases.
40
What does it mean, if Circadian effects of light are phase dependent
it can be seen that the effects of light pulse differs at different circadian points. - Evening light delays the clock, - morning light advances the clock
41
Type‐1 resetting
small phase shifts of only a few hours and little or no reduction in endogenous circadian pacemaker amplitude
42
Type‐0
large phase shifts of up to 12 hours, occurs via prior reduction of circadian pacemaker amplitude
43
Markers of body clock?
core body temperature cortisol melatonin
44
Circadian effects
effects of light exposure on the phase angle of entrainment and may persist over longer time
45
Acute effects
light exposure effects that emerge upon or during light exposure, but dissipate after the light exposure
46
ipRGCs
Intrinsically Photosensitive retinal ganglion cells - o Detects light through melanopsin. So sensitive around 480 nm.
47
Melanopsin
a photopigment with which absorbs light around 480nm.
48
Light acts on the body by two pathways:
- Image forming pathway (The primary optic tract) o Visual effects o Visual reflexes - Non image forming pathway (Retinohypothalamic tract) o Circadian, endocrine and neurobehavioural functions o Most sensitive to blue light

Psychology of Light and Time (2 decks)

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