Sleep, Dreaming and Circadian Rhythms Flashcards

1
Q

Electroencephalogram (EEG)

A

reveals brainwaves

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2
Q

Electrooculogram (EOG)

A

Records eye movements seen during rapid eye movement (REM) sleep

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3
Q

Electromyogram (EMG)

A

Detects loss of activity in neck muscles during some sleep stages.

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4
Q

Emergent Stage 1 EEG:

A

accompanied by REM and loss of muscle tone. called REM sleep.

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5
Q

sleep spindles

A

12-14 Hz

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6
Q

Stage 3 and 4 also known as

A

slow wave sleep (SWS)

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7
Q

REM Sleep and Dreaming

A

80% of awakenings from REM lead to dream recall. External stimuli can be incorporated into dreams. Dreams run on “real time.” Virtually everyone dreams.

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8
Q

Sleepwalking (somnambulism), sleeptalking and bedwetting (enuresis) occur more frequently

A

during Stage 4 than during REM sleep, when core muscles are relaxed.

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9
Q

Freud’s explanation of dreams:

A

dreams are triggered by unacceptable repressed wishes. Our dreams (Manifest dreams) are disguised versions of our real dreams (Latent dreams). Interpreting dreams would expose the latent dreams and cure the patients.

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10
Q

Activation-Synthesis

A

Modern alternative to Freud’s explanation of dreams. Dreams due to cortex’s attempt to make sense of random brain activity.

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11
Q

Recuperation theories

A

Wakefulness causes a deviation from homeostasis, resulting in physiological and behavioral disturbances. Sleep is needed to restore homeostasis. After sleep deprivation, missed sleep will be regained.

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12
Q

Circadian theories

A

Sleep is the result of an internal timing mechanism that evolved to protect us from the dangers of the night. Missed sleep cause little or no disturbances. Little or no compensation for missed sleep.

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13
Q

Good correlation between the time an

A

animal needs to feed, and how vulnerable it is during sleep.

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14
Q

Conclusions of sleep

A

1) all animals sleep, 2) all species sleep, sleep does not serve some special higher-order human function, 3) duration of sleep varies among species, sleep is not necessarily needed in large quantities, 3) no clear correlation between sleep time and activity levels, body size, or body temp.

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15
Q

Circadian rhythms

A

about a day. Virtually all physiological, biochemical, and behavioral processes show some circadian rhythmicity (sleep, temp, hormones).

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16
Q

Zeitgebers

A

environmental cues that entrain circadian cycles (light-dark, tides).

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17
Q

without zeitgebers

A

, animals display “Free-Running Rhythms”, usually longer than 24h, ~ 25h.

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18
Q

Human’s free-running circadian sleep-wake cycle lasts

A

25.3 hrs.

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19
Q

Jet lag

A

zeitgebers are accelerated during east-bound flights (phase advance) or decelerated during west-bound flights (phase delay). Phase delays are tolerated better.

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20
Q

shift work

A

zeitgebers unchanged, but sleep-wake cycle must be altered. These changes may result in large phase shifts.

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21
Q

Jet lag and shift work produce

A

fatigue, sleep disturbances, physical & cognitive deficits.

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22
Q

melatonin

A

is synthesized in the pineal gland. not a sleep aid, but may be used to shift circadian rhythms. Melatonin levels follow circadian rhythms controlled by the Suprachiasmatic Nucleus.

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23
Q

Can the effects of Jet Lag be prevented or minimized?

A

Melatonin and Light therapy.

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24
Q

Pineal gland triggers

A

seasonal reproductive changes in fish, birds, reptiles, and amphibians – human function is unclear.

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25
Q

Resetting biological clock with bright lights

A

morning: earlier sleep, phase advance
afternoon: little effect
evening: later sleep, phase delays

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26
Q

Resetting biological clock with melatonin pills

A

morning: later sleep, phase delays
afternoon: earlier sleep, phase advance
evening: little effect

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27
Q

The Recuperation theory (wakefulness has a debilitating effect) predicts that sleep deprivation will cause:

A

1) Long periods of wakefulness will produce physiological and behavioral disturbances.
2) These disturbances will grow steadily as deprivation continues.
3) The missed sleep will be regained.

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28
Q

The Circadian (evolutionary) theory predicts that sleep deprivation will cause:

A

1) There will be no debilitating effect, except for tendency to fall asleep.
2) Tendency to sleep will be during normal sleeping time.
3) There will be little or no compensation for the loss of sleep.

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29
Q

3-4 hours of deprivation in one night

A

Increased sleepiness. Disturbances of mood. Poor performance on tests of vigilance.

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30
Q

2-3 days of continuous deprivation

A

Experience microsleeps, naps of 2-3 seconds. Micro sleeps disrupt performance on vigilance tests.

31
Q

Longer periods of deprivation

A

No effects on motor performance. No effects of cognitive performance (IQ). May affect creativity.

32
Q

Sleep-Deprivation Studies with Rats

A

Carousel apparatus used for sleep deprivation. When the EEG indicates sleep, the floor rotates – the sleeping rat falls into the water and wakes up.
Yoked controls – subjected to the same floor rotations.
Experimental rats typically die after several days. Postmortem studies reveal lesions indicative of extreme stress.

33
Q

The circadian clock is located in the

A

Suprachiasmatic Nucleus. Even when isolated, it shows cycles of electrical, metabolic and biochemical activity. The Retino-
hypothalamic tract connects the retina with the Suprachiasmatic nucleus.

34
Q

photoreceptors that entrain the SCN are

A

light-sensitive ganglion cells.

35
Q

transection before the optic chiasm

A

eliminated the ability of light-dark cycles to entrain circadian rhythms.

36
Q

transection after the optic chiasm

A

did not eliminate the ability of light-dark cycles to entrain circadian rhythms.

37
Q

these two transections suggest that

A

the sensory tracts that mediate the entrainment of circadian rhythms by light-dark cycles branch off from the optic chiasm and project to the suprachiasmatic nuclei of the hypothalamus.

38
Q

Hypnotic drugs

A

increase sleep. most commonly prescribed hyponotic drugs: benzodiazepines – Valium, Librium. Effective in the short term. Complications include: tolerance, cessation leads to insomnia, addiction, increase of stage 2 sleep, decrease of stage 4 and REM.

39
Q

Antihypnotic drugs

A

decrease sleep. Stimulants: cocaine, amphetamine. Tricyclic antidepressants: imipramine. Both increase activity of catecholamines (norepinephrine, epinephrine, dopamine). Can suppress REM with little effect on total sleep time.

40
Q

insomnia

A

Disorder of sleep initiation and maintenance. Often a problem of too little undisturbed sleep
Often is iatrogenic (physician-created), which is a consequence of pill use.

41
Q

sleep apnea

A

stop breathing leads to repeated awakenings.
- Obstructive –atonia and collapse of respiratory tract.
- Central – CNS fails to maintain breathing
Patients are frequently overweight, elderly.

42
Q

Restless leg syndrome

A

prevents sleeping

43
Q

Alternative treatment of Insomnia:

A

sleep restriction therapy.

44
Q

Hypersomnia, Narcolepsy

A

Severe daytime sleepiness and repeated brief daytime sleeping - “sleep attacks.” REM without atonia.

45
Q

cataplexy

A

loss of muscle tone while awake.

46
Q

sleep paralysis

A

paralyzed while falling asleep or upon waking.

47
Q

Hypnagogic hallucinations

A

dreamlike experiences while awake. Possibly due to abnormalities in mechanisms triggering REM.

48
Q

A 1977 study of 8 subjects who gradually reduced their nightly sleep to 4.5 - 5.5 hours found:

A

Daytime sleepiness when sleep was reduced to 6 hours. Increased sleep efficiency: faster falling asleep, more stage 4 sleep, fewer awakenings. In the year after the experiment, all subjects slept less than at the beginning of the experiment.

49
Q

Long-term sleep reduction by napping

A

Leonardo da Vinci took 15 min naps every 4 hours.

50
Q

circannual

A

cycles can last about a year. hibernation, seasonal changes in reproduction or body fat.

51
Q

alert wakefulness

A

low amplitude, high frequency EEG waves (beta): 13-30 Hz.

52
Q

just before sleep

A

bursts of alpha waves appear (8-12 Hz).

53
Q

stage 1 (initial stage 1)

A

Low amplitude waves, frequency slower than alert wakefulness.

54
Q

stage 2

A

Amplitude of waves increases and frequency slows down. K complexes appear: single positive (downward deflection) and negative wave (upward deflection). Sleep spindles appear: 1-2 sec burst of 12-14 Hz waves.

55
Q

stage 3

A

Amplitude of waves increases and frequency slows down. Delta waves appear occasionally: 1-2 Hz

56
Q

stage 4

A

Predominance of delta waves.

57
Q

waking from non REM sleep leads to only

A

7% percent of dream recall

58
Q

lucid dreams

A

Dreams in which the dreamer is aware that he/she is dreaming and can influence the course of the dreams. It is like being awake in a dream.

59
Q

for reducing jet lag

A

Gradual shift of one’s sleep-wake cycle in the days before the trip. Light treatment early in the morning after east-bound flights facilitate the phase advance required for adjustment. Studies in hamsters suggest that a vigorous workout early in the morning may also help.

60
Q

for reducing shift work

A

Shifts to schedules that begin later in the day produce fewer disturbances because they require phase delay. It is easier to go to bed and get up later than the reverse.

61
Q

after sleep deprivation, there tends to be more

A

REM periods.

62
Q

following REM sleep deprivation

A

there is a REM rebound: subjects have more REM sleep in the following 2-3 nights. if REM is replaced by a similarly long period of wakefulness, there is no REM compensation, confirming idea that wakefulness and REM sleep are equivalent in many ways.

63
Q

REM sleep may:

A
  1. Maintain mental health
  2. Maintain motivation
  3. May be necessary for the processing of certain memories (consolidation)
    There is some experimental support, however certain tricyclic antidepressants (imipramine) can eliminate REM without serious consequences.
64
Q

individuals who are deprived of sleep become more efficient sleepers

A

They take less time to fall asleep. They have fewer interruptions of sleep. These subjects show a higher proportion of Slow Wave Sleep. Although total sleep is not regained, stage 4 sleep tends to be regained, with corresponding reductions in stages 1 & 2.

65
Q

The idea that stage 4 may be specially important and restorative is supported by

A

the fact that short sleepers have as much stage 4 sleep as long sleepers. Also, waking up sleepers during stage 4 produces more sleepiness than waking them up during REM.

66
Q

posterior hypothalamus promotes

A

wakefulness.

67
Q

anterior hypothalamus promotes

A

sleep.

68
Q

melatonin increases

A

sleepiness. Increased secretion of melatonin begins between 8-10 pm, and decreases during the day. Melatonin resets clock by acting on receptors of the SCN.

69
Q

Nocturnal myoclonus

A

Periodic twitching of the legs and body leads to poor sleep.

70
Q

In normal subjects, a nucleus in the caudal reticular formation (nucleus magnocellularis)

A

normally induces muscle relaxation during REM. Studies in a strain of narcoleptic dogs has shown that this nucleus is also active during narcoleptic attacks, which would cause the collapse of the subjects during these attacks.

71
Q

orexin

A

Studies in these dogs also revealed the genes associated with narcolepsy. These genes encode a receptor protein that binds a neuropeptide neurotransmitter called orexin. These dogs are deficient in this protein. Orexin is synthesized in the posterior hypothalamus, which promotes wakefulness.

72
Q

In humans suffering from narcolepsy

A

the cause of narcolepsy appears to be a hereditary disorder that stimulates the immune system to attack and destroy orexin-secreting neurons. Symptoms typically appear during adolescence. Interestingly, deficiencies in the orexin-binding protein are not only associated with narcolepsy, but also with a decrease in eating behavior.

73
Q

Patients that due to injury or other reasons do not have REM sleep are often

A

not affected by lack of REM sleep.

74
Q

Some patients experience REM sleep without

A

core-muscle atonia, which is thought to prevent the acting out of dreams.