L1 Hx of sleep medicine Flashcards
1 sleep disorder
sleep deprivation
NOT diagnosible
Leading Theories of Why We Sleep
- Restoration and recovery
- Energy conservation
- Predator avoidance
- Memory consolidation
REMP
Restoration and recovery
Restores biological processes degraded in wakefulness
Increase in growth hormones
Energy conservation
Metabolism drops 5-10%
Endothermy internal regulation of temperature
Sleep needed to offset high energy cost
Hypothalamus regulates body temp
Predator avoidance
Lying still is less likely to attract a predator
Most predators are active at night
Tonic (as in muscle tone) immobility reflex aka animal hypnosis or death feigning – last line of defense against an attacking predator
Total immobilization so animal appears dead - predators not interested in dead prey
Similar to REM sleep when body is almost paralyzed
Reflexes are suppressed
Body temp drops
Memory consolidation
Idea that memories are consolidated best during REM sleep:
Brain cells grow and make neuronal/synaptic connections
Can increase in strength
“Neurons that fire together wire together”
Fine tune binocular vision system
Unimportant memories disappear
Harmless discharge of strong emotions
Activation synthesis theory
Part of memory consolidation theory
dreams occur bc neurons are firing and brain is trying to make sense of it
Who was Robert MacNish and what did he believe?
1834
Author, Philosophy of sleep
Sleep = passive, inactive state of the brain
Sleep occurs bc of lack of stimuli at night/reduced sensory input
Wakefulness occurs bc bombardment of stim from environ
No distinction b/w sleep, paralysis, stupor, intox, hypnosis, etc.
Hypnotoxin theory
19th century fatigue products (toxins and the like) accumulate through the day, finally causing sleep, during which they are gradually eliminated
Who is Nathaniel Kleitman
1928, Founder of sleep medicine
FInds those who are sleep deprived are impaired
People who stayed awake all night will be more impaired at night than next day (no support hypnotoxin theory)
Greatest impairment after 60 hours
Sleep a passive process / the absence of wakefulness
Richard Caton was the first to use…
1875
Physiologist who is experimenting with animals
Put electrodes on animals, can measure brain waves / electrical activity
EEG – electroencephalogram
Used paper to record activity
Hans Berger found..
Recorded electrical activity in the human brain
Sleep could be measured quantitatively
What did Davis and Harvey do/find?
Describe major elements of sleeping brainwave patterns
Take brief samples of brain activity while people sleep
Sleep characterized by high amplitude slow waves
Can happen from ½ per sec to 4 per sec
Wakefulness by low amplitude fast waves (alpha)
14 per second
Evidence for sleep being a passive process
Reticular Activating System
1949
Thought to be endogenous mechanism in brain
Area which stimulates alertness and makes you stay awake
Lesions in the RAS gives delta sleep (very slow like a coma)
Edouard Gelineau discovered?
1880 Discovered Narcolepsy Narke - stupor, unconscious Lepsis - seizure/overtaken Triggered by strong emotion
Richard Henenberg discovered?
1916, Cataplexy - collapse of muscles
Charles Dickens wrote about what?
1836
Obstructive Sleep Apnea
“Posthumous Papers of the Pickwood Club” -Joe
Obesity, hypoventilation syndrome
Freud on dreams
“The royal road to the unconscious”
Book – “The Interpretation of Dreams”
Theory of dreams inspired much interest in sleep
Dreams were repressed urges
Too threatening to come about during the day
Ego goes to sleep at night
Id is building up steam during the day – can be released symbolically at night
Needed a medical degree to practice psychoanalysis
Chronobiology means…
Study of biological rhythms
Definite 24 hour period of life
John Jacques de’Ortous deMairan - what did he discover?
Heliotropic plant – plant that is attracted to the sun
Plant that is open during the day and closed at night … continues to open and close despite having no exposure to the sun = on an endogenous cycle / internal chronobiology
Circadian rhythms - meaning of the word
“About a day”
Circa = about
Dia = day
Kleitman and infants - what was he interested in and what did he find?
interested in cycles of activity and inactivity
Hypothesized that their hunger is adaptive and recurring, therefore making their waking times unusual and sporadic
First to notice the fluttering of the eyelids – notices rapid movement right when child sleeps … slowing of the movement … then seems to disappear with deeper sleep
What movement produces the greatest neocortical activation - more so than any other movement?
Eye movement
superior colliculus activates before eye movement
Eugene Aserinsky - who and what did he do?
Kleitman’s student
Looking for a way to find when eye movement begins
Were measuring 5 minutes epochs (intervals)
Device that measures eye movement – EOG (electrooculogram)
Found that when adults fall asleep, it was gradual and into delta waves and stages (will have rapid periods), whereas infants go into sudden onset REM sleep periods (SOREMPS) – like narcolepsy
Basic cycle of sleep identifies at this time due to EOG and EEG
Aserinsky and Kleitman unsuccessful initially because…
Not enough paper
Needed to nap in between
Aserinsky and Kleitman made which huge discovery and how did they go about it?
Began to wake people up during eye movement and not … found dreams mostly during the eye movement
**Identifying 2 types of sleep
When was the first article published on theory of dual REM sleep? And what happened to it?
1953
Squashed bc went against scientific theory of RAS
Dementhe and Kleitman - what did they do?
1957 continuous EEG recordings 126 nights 33 subjects described and quantified occurrence of REM
Stage 1
4-5%
light sleep
muscle activity slows down
occasional muscle twitching
Stage 2
45-55%
breathing pattern and heart rate slow
slight decrease in body temp
Stage 3
4-6 percent
deep sleep begins
brain begins to generate slow delta waves
Stage 4
12-15% very deep sleep rhythmic breathing limited muscle activity delta waves
Stage 5
REM 20-25% brainwaves speed up, almost indistinguishable from when awake dreaming occurs muscles relax heart rate increases breathing rapid and shallow
EMG
electromyography
measures muscle movement
EEG
electroencephalography
measures brain waves (electrical activity in the brain)
EOG
electrooculography
measures eye movement
(occipital)
why are we paralyzed by sleep?
bc of the PONS
part of the brain that shuts down the impulse to the spinal cord
What did Michel Jouvet discover?
Suppression of muscle activity
Dementhe discovered..
Complete suppression of reflexes during REM
Types of movement disorders
- Restless leg syndrome
- Sleep paralysis
- Periodic limb movement disorder
RESTLESS
PARALYSIS
LIMB MOVEMENT
Duration of interval from one eye movement period to the next..
90-100 minutes
What did the regular occurrence of REM indicate?
That dreams did not occur b/c of sleep disturbances
