LMBR8: SLEEP 1 B P 256-269

Question 1

What is the following

Suprachiasmatic nucleus (SCN)

BR 263 & 277

Answer 1

A1: the main body “clock” or central “clock”. This is a portion of the hypothalamus that regulates melatonin secretion and creates the circadian rhythm in the body. Responsible for the awakening cortisol spike

Question 2

What is the following

Melatonin

BR 277

Answer 2

A natural hormone that is made in the pineal gland and helps regulate sleep and wake cycles.

Question 3

What is the following

Circadian rhythm

BR 277

Answer 3

A biological process that regulates physiological functions and behaviors over 24-hour period that aligns with the light dark cycles. It’s also known as the “body clock”. The circadian rhythm is regulated by endogenous oscillators.

Question 4

What is the following

Endogenous or internal circadian oscillators

BR277

Answer 4

The molecules, cells and tissues that make up the bodies “internal clock”. They produce oscillating (alternating) currents through self-regulating positive and negative feedback loops that produce the circadian rhythm. Endogenous oscillators include both the central and peripheral oscillators.

Question 5

What is the following

Central Oscillators

BR 277

Answer 5

these are found in the suprachiasmatic nucleus (SCN), which is the main body “clock”.

Question 6

What is the following

Peripheral Oscillators

BR 277

Answer 6

These are present in many major organs in the body (kidneys, liver, heart, adrenal glands, and pancreas). They allow for synchrony and alignment between the central and peripheral clocks.

Question 7

What is the following

: Entrainment

BR 277 & 262

Answer 7

The ability to be brought into a rhythm. Synchronization of the internal endogenous oscillators based on external (out of the body) inputs

Question 8

What is the following

Retinal Ganglion Cells (RGC)

BR 277

Answer 8

non-visual light sensitive retinal neurons that relay light intensity/spectra to the SCN.

Question 9

What is the following

Inputs (Sleep)

BR 277

Answer 9

The external and environmental factors that can entrain the circadian rhythm.

Question 10

What is the following

Modifiers (Sleep)

BR 277

Answer 10

things that change the amount of “input” that gets to the body’s operators

Question 11

What is the following

Operators (Sleep)

BR 277

Answer 11

The body’s reaction or response to the modified input

Question 12

What is the following

Outputs (Sleep)

BR 277

Answer 12

The behavioral and physiological consequences of the operators.

Question 13

What is the following

Ambient temperature

BR 277

Answer 13

temperature of the surrounding environment.

Question 14

What is the following

Blood Osmolality

BR 277

Answer 14

A measurement of the particles (such as sodium, potassium, and chloride) dissolved in the plasma.

Question 15

What is the following

Blue Light

BR 267 & 277

Answer 15

A specific range within the spectrum of light, 420-480nm, 6500 kelvin color.. Blue light creates greater melatonin suppression at lower intensities and shorter durations and has disruptive nighttime effects. Examples blue sky, fluorescent lights

Question 16

List cultural impacts on health

BR 261

Answer 16

6
1) Sleep viewed as inconvenient or wasted time
2) Functioning on small amount of sleep is considered as strength, courage or
productivity
3) Sleep is intentionally limited
4) Early morning/ late evening may be only time available for focused, uninterrupted
work
5) Night shift workers (20% of workers)

Question 17

1) The indirect costs of insomnia are estimated at how much/year?
2) What are they?

BR 261

Answer 17

1) $60 billion
2) -Presenteeism (at work, not productive)
- Increased risk of long term disability

Question 18

1) How many US adults are have frequent difficulty sleeping?
2) What percentage seek medical attention?

BR 261

Answer 18

1) 60 Million
2) Only 10%

Question 19

T/F: The percentage of young adults who sleep LESS than the average US adult has doubled from 1960 to 2002.
What is this percentage?
BR 261

​

Answer 19

True
37%

Question 20

There has been ___________ in short sleep duration in all age categories from 1970 to
present
A) Significant Decrease
B) Minor Decrease
C) No change
D) Minor Increase
E) Significant Increase
BR 261

Answer 20

E- Significant Increase

Question 21

1) What is the average amount of sleep for US adults?
2) T/F: 10% sleep less than 6hrs/night

BR 261

Answer 21

1) 6hrs 57min
2) False - 20% sleep less than 6hrs/night

Question 22

Regarding sleep, which of the following statements is inaccurate?

a) General requirements of sleep is usually 7-8 hours of sleep/day with a considerable
range for individual subjective sleep needs
b) Lack of sleep usually has no impact on function and if it does, the person is aware of
the impairment
c) There is no recognized objective test for how much sleep a person needs
d) ⅓ of life is spent sleeping.

BR 261

Answer 22

B - Sleep deficiency impairs functional performance, and often individuals are unaware of
the level of impairment.

Question 23

What is Sleep Propensity

BR 262

Answer 23

The ability to transition to sleeping, if a person is awake; or to stay asleep, if a person is
sleeping.

Question 24

In terms of environmental factors, what entrains the wakefulness/sleep cycle? The
awakening cortisol spike?

BR 262

Answer 24

Wakefulness–sleep cycle is entrained by day–night cycle. Social and familial factors can also contribute. Awakening cortisol Spike is in trained by food anticipation, meal timing.

Question 25

How is melatonin secretion regulated by the SCN?

BR 262 & 263

Answer 25

a) Retina Ganglion Cells, melonopsin => Neuronal Tract => SCN => Central oscillators entrained => Neuronal Tract to Pineal Gland => Melatonin secretion
- Melanopsin- photopigment in RGC, maximally sensitive to short wavelengths
of light- Blue light. Amount of melonpsin relays light intensity and spectra to SCN
which affects timing of melatonin secretion.
AKA
Light => less melonopsin => decrease melatonin
Dark => more melonopsin => increase melatonin

b) SCN => Sphlanic nerves => adrenal gland => secretes epinephrine, norepinephrine,
glucocorticoids, and aldosterone => regulates blood flow, temperature and food intake => Melatonin, biofeedback loop => adrenal gland

Question 26

What are the inputs that entrain the circadian rhythm?

BR 264 & 266

Answer 26

1) Light intensity
2) Light wavelength (frequency, color)
3) Food (carbohydrates)
4) Fluid (blood osmolality-sodium, potassium, chloride in the plasma)
5) Ambient temperature

Question 27

Which of the following is NOT a modifier of the circadian rhythm?

a) Pupillary reflex
b) PER & CRY SNP’s
c) Cutaneous blood flow
d) Sunglasses

BR 264

Answer 27

C - Cutaneous blood flow is an operator. Cutaneous fat stores which affect core and
extremity temperature, and vascular tone, which affects fluid volume modifying core and
peripheral temperatures, are additional modifiers. Pupillary reflex limits the amount of light
getting to retina ganglion cells. Sunglasses or back light on electric devices change the
intensity of light reaching retina ganglion cells. SNPs (single nucleotide polymorphisms) are
genetic variations in the DNA. They can occur in PER & CRY proteins, which are integral in
controlling the circadian rhythm.

Question 28

T/F: Excess cutaneous fat stores dampens the body’s ability to thermoregulate.

BR 264

Answer 28

True. Cutaneous fat stores affect core and extremity temperature. If there is too much, itdampens the bodies ability to thermoregulate. If there is not enough, it accelerates it.

Question 29

What is the role of PER & CRY SNPs in modifying the circadian rhythm?

BR 264

Answer 29

They inhibit function of other proteins, like the proteins regulating the “clock” and “cycle” of
sleep, until they degrade in 24hrs. Light exposed to retinal ganglion cells produces more
PER protein. If SNMs occur in PER and CRY proteins causing them to function
inappropriately, the circadian rhythm may not work.

Question 30

Vascular tone affects fluid volume in blood vessels which modifies core and peripheral
temperatures. Which of the following statements is accurate?
A) Nitric oxide and estrogen enhance vasodilation and lowers blood pressure.
B) Nitric oxide and estrogen enhance vasoconstriction and raises blood pressure.
C) Sodium causes acute vasodilation and lowers blood pressure.
D) Sodium causes acute vasoconstriction and lowers blood pressure.

BR 265

Answer 30

A- Nitric oxide and estrogen enhance vasodilation and lowers blood pressure. Sodium
causes acute vasoconstriction and raises blood pressure.

Question 31

Operators are the body’s responses or reactions to modified inputs in the circadian rhythm.
What are they?

BR 265

Answer 31

1) Core body temperature changes
2) Melatonin suppression or secretion
3) Cortisol secretion, timing of cortisol spike
4) Increased or decreased cutaneous blood flow

Question 32

The behavioral and physiological consequences of the operators, or outputs in circadian
cycle, include Sleep and Food seeking behaviors, including quantity and quality. What are
some of the functional performance effects?
BR265

Answer 32

1) Alertness
2) Kinetic activity
3) Motor skills, including precision
4) Strength and stamina

Question 33

Sleep is divided into stages. For each statement, specify which stage it occurs: Onset, early
sleep, throughout sleep, late sleep or awakening.
1) Restorative sleep (slow wave on EEG)
2) Cortisol spike
3) DNA remodeling and repair
4) Cooling of core body temp
5) Warming of extremity
6) Core body temp nadir
7) Longer REM periods
8) Gradual increase in cortisol 9) Melatonin secretion
10) Increasing blood pressure and sympathetic tone
11) Leptin secretion (controls appetite)
12) Decreased blood pressure and sympathetic tone
13) Cutaneous vasodilation
14) Declining melatonin levels
15) Darkness triggers melatonin secretion
16) Fatty acid metabolism
17) Decreasing core body temp with increased peripheral skin temp to start physiologic
restorative processes in body
18) Increasing baroreceptor sensitivity (the body’s ability to change blood pressure
rapidly by modifying heart rate, heart contractibility, and peripheral vascular tone
19) Continued rise in melatonin levels

BR 265 & 266

Answer 33

1) Early sleep
2) Awakening
3) Throughout sleep
4) Onset
5) Onset
6) Early sleep
7) Late sleep
8) Throughout sleep
9) Onset
10) Late sleep
11) Throughout sleep
12) Early sleep
13) Onset
14) Late
15) Onset
16) Throughout sleep
17) Early sleep
18) Late sleep
19) Early sleep

Question 34

Which of the following statements is accurate of normally entrained endogenous rhythms?
A) As melatonin levels rise, core temp decreases and sleep propensity increases
B) As melatonin levels rise, core temp increases and sleep propensity increases
C) As melatonin levels rise, core temp decreases and sleep propensity decreases
D) As melatonin levels rise, core temp increases and sleep propensity decreases
E) There is no relationship between melatonin levels, core temp and sleep propensity

BR266

Answer 34

A- As melatonin levels rise, core temp decreases and sleep propensity increases

Question 35

What is the predominant entraining force of the central SCN clock? What are its
components?

BR 266

Answer 35

Light. Light intensity, Light spectra, timing of light exposure in 24hr cycle, duration of light
exposure

Question 36

What is the amount of intensity of each of the following in lux?

1) Bright sunlight at noon
2) Cloudy day
3) Overcast day
4) Bright industrial lighting
5) Offices and kitchens
6) Household lighting
7) Average nursing home
8) Street lighting
9) Full moon
10) Moonless light

BR 266 & 267

Answer 36

1) 100K lux
2) 25K lux
3) 2K to 10K lux
4) 1K to 5K lux
5) 200 to 500 lux
6) 50 to 200 lux
7) 50 lux
8) 20 lux
9) 1 lux
10) 0.001-0.0001 lux (8 orders of magnitude less than bright sunny day)

Question 37

What is Kelvin Color?

BR267

Answer 37

Kelvin color is a number that describes the dominant color tone produce at a certain
temperature in Kelvin. Lower temperatures in Kelvin lead to warmer colors of light (red,
orange). Higher Calvin temperatures lead to cooler lights (blue, violet).

Question 38

What are the nighttime effects of blue light? What are examples of blue light exposure even
at low intensities of light?
BR 267

Answer 38

Blue light at night time increases cortisol, nighttime heart rate, blood pressure, sympathetic
tone and core body temperature. It suppresses melatonin. It decreases sleepiness and
causes alertness, inhibiting sleep onset and shifts the sleep cycle later.

Examples include back lit computers, TV screens, phones, and other screens as these have
strong blue spectra components. Also typical night time household lighting of intensities 50
to 100 Lux.

Question 39

What are the effects of light during the day? How does low daylight affect the sleep cycle?
BR 267

Answer 39

Light during the day suppresses melatonin and supports alertness.

Low daylight decreases daytime activity, alertness, positive affect, core body temperature
amplitude/max and increases melatonin suppression with evening light. Low daytime light
significantly increases the sensitivity of melatonin suppression from late at night. Daytime
exposure of 10 K Lux of light for 6.5 hours cannot fully eliminate night time melatonin
suppression from exposure to 90 lux of light. If low light exposure has occurred 2 to 3 days
prior, the SCN is more sensitive to light at night, resulting in higher melatonin suppression,
possible delayed onset of sleep, and shifting of the sleep cycle.

Question 40

What is the ideal SCN clock? How was it traditionally reset? What makes it more difficult to
reset now?

BR 268

Answer 40

The ideal SCN clock is 24 hour circadian rhythm with consistent sleep and wake times. It
was traditionally naturally reset by the solar cycle of day/night. It is now more difficult to reset
due to inappropriately timed light signals from electricity (lights).

Question 41

Match the statements with the phase shift of the SCN- delayed or advanced?

a) SCN longer than 24hrs
b) SCN shorter than 24hrs
c) Westward travel
d) Eastward travel
e) Exposure to light earlier in the day

f) Evening light exposure
g) Person gets more and more behind in their objective time clocks
h) Home lighting of 100 to 1000k, leading to 100% melatonin suppression
i) Person gets more and more ahead of objective time
j) Night “owls”
k) Morning “larks”
l) Most common
BR 268

Answer 41

a) Delayed
b) Advanced
c) Delayed
d) Advanced
e) Advanced
f) Delayed
g) Delayed
h) Delayed
i) Advanced
j) Delayed
k) Advanced
l) Delayed

Question 42

Most people have SCN clock of ___ hrs and __min, ______ phase shift. In General, SCN
needs to be reset forward (advanced) or reset backward (delayed) by ___ to ___ min/day.

BR 268

Answer 42

24hrs and 8min. 5 to 15

Question 43

To maintain entrainment of SCN, how must the daily adjustments be made?

BR 268

Answer 43

If shorter than 24 hours, advancement of ~10 minutes or less is needed. Example, delaying
exposure in light in morning by 10 minutes or ideal wake up time. If longer than 24 hours,
backward setting of ~ 20 minutes or less is needed. Example, limiting light 20 minutes earlier
in evening so ideal bedtime can be achieved.

Question 44

What are the effects of sleep delay and disruption?

BR 268

Answer 44

Decreased daytime activities/attention, positive affect, social ability, REM sleep, and
melatonin. Metabolic effects include decreased caloric burn, leptin (appetite control
hormone) and core body temperature amplitude/max; increased appetite and insulin
resistance.

Question 45

What role do carbs play in sleep-wake cycle? How can carbs be shifted if someone is falling
asleep too early or too late?

BR 268

Answer 45

Skipped, late, or low-carbohydrate breakfast lead to diminished cortisol awakening rise.
Eating breakfast shortly after awakening may help shift wake-up time earlier. Eating a high
carb breakfast may improve sleep-wakefulness transition. Eating dinner too early may
contribute to falling asleep too early.
-
To shift carbohydrates if someone is falling asleep too early, they can eat more
carbohydrates at dinner. If someone is falling asleep too late, they can shift carbohydrates to
earlier meals, avoid snacking and carbohydrate rich dinners, and eat an earlier dinner.

Question 46

How is body temperature controlled? What is the normal trend for core and peripheral body
temp in the afternoon and evening?

BR 269

Answer 46

Body temperature is controlled by three main elements:
1) the heat producing body core, which is generally homeostatic
2) the heat losing peripheral body, which varies widely in temperature in response to
blood flow
3) the ambient temperature of the surrounding environment
-

Normally, during the afternoon, core body temperature will rise and peripheral extremities will
cool. During the night, the opposite will occur as heat shifts from the core to the peripheral
extremities and heart rate and cardiac output are reduced.

Question 47

What role does higher blood osmolality and decreased fluid volume play in sleep wake
cycle?

BR 269

Answer 47

In late afternoon, higher blood osmolality leads to higher afternoon peak core body
temperature because of an increase in internal temperature threshold, increased blood flow
the vital organs and less output to the peripheral body. Decreased fluid volume can reduce
amount cutaneous blood flow needed for core cooling at night; and increases cardiac
activation, sympathetic tone which shunts blood to core.

Question 48

T/F
1) If peripheral body is not warm enough during transition to sleep, sleep onset may be
inhibited.
2) Ambient temperature has no role in peripheral body temperature.
3) Benzodiazepines, yoga, non-sleep meditation and autogenic training shift heat to
core.
BR 269

Answer 48

1) True
2) False - Ambient temperature is a strong determinant of peripheral body temperature.
3) False - Benzodiazepines, yoga, non-sleep meditation and autogenic training all
produce a similar effect in the body‘s natural shift of heat to the extremities. With
these antecedents, blood is shunted from the core to the extremities as sympathetic
activation in the muscles and skin, heart rate, and energy expenditure are all
reduced.

Question 49

Regarding Melatonin and behavioral health disorders, specify the percentage of melatonin
suppression in the following conditions:
a) Major depression disorder
b) Seasonal affective disorder
c) Bipolar disorder

BR 269

Answer 49

a) ~20%
b) ~40%
c) ~45%

Question 50

Which of the following statements is inaccurate?
A) Elderly adults experience melatonin suppression partially due to cataracts/corneal
opacity
B) Corneal opacity, often due to cataracts limits retinal exposure
C) Retinal illuminance reduces as one ages, with short light wavelengths (blue light)
most affected and longer wavelengths (red light) least affected
D) A 45-year-old has 50% lower retinal illuminance than a 10 y/o
E) A 65-year-old has 25% lower retinal illuminance than a 45 y/o

BR 269

Answer 50

E- A 65-year-old has 50% lower retinal illuminance than a 45 y/o, not 25%