Class notes
Psychology of Sleep
- Course
- PSYC 444
- Institution
- McGill University (Mcgillu)
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PSYC 444 SleepLecture 1
What is sleep?
- Behavioral view
o Inactivity, unresponsive, we define sleep as a specific form of EEG.
o Can look at brain waves. If unresponsive, in some stages. Snoring is most definite
way of sleeping.
o Sleeping is categorized by data, measure by waves
- Sleep scientist view
o Polysomnographic markers
How data is collected, and why is it meaningful? Looking at sleep stages,
its arbitrary when the cut off is.
- Subjective experience
o The feeling of being asleep, dreaming, and parasomnias.
o There’s something we know about ourselves, did we sleep well, poorly, etc
Overarching themes of class: dynamic balance and rich cognitive life
- Homeostasis: an organism needs to maintain internal stability in the face of
environmental perturbations
- Dynamic balance: the system looks stable and unchanging, but is in fact constantly
adapting to change both in its internal states and in the environment
- Rich cognitive life: sleep is not a state of “oblivion”
- What does this mean for sleep:
o Themes: activity, cyclicity, waking, amount, self-world
Who studies sleep?
- Psychologists, neurologists, neuroscientists, clinicians, philosophers,
- Very little resources available to general population
History of sleep
- Do not have 1 established theory about sleep, lots of theories.
Why we sleep
- Homeostatic theory
o Life is demanding, sleep allows to conserve energy
o Sleep is involved in thermoregulation
- Cognitive theory
o Sleep is price for brain plasticity, downscaling synaptic strength in sleep allows
for more cognitive function in wave
,Basic notions
- Sleep is ubiquitous
- Do all animals sleep
o Unicellular organisms, insects, amphibians, fish, birds, mammals, plants??
Sleep and consciousness
- Difficulty to define the relationship between sleep and consciousness
- What is the difference between someone asleep, unconscious or comatose
- Many taxonomies have been proposed
- Main problem: definition of consciousness varies widely between researchers in the
same domain and especially between domains (neuroscience, psychology, philosophy,
medicine, etc)
3 classic states of consciousness/awareness
- Wake
o awareness of self and environment
o Fast reflexes
o Mental activity is spontaneous and intentional
People don’t believe in just wake anymore, meditative wake, brain
surgery wake, different types of wakes.
Spontaneous, thoughts just appear, mind wandering, its intentional you
have the choice
- Deep sleep
o Slow wave sleep/Delta sleep, non-rapid eye movement/NREM sleep
o No explicit awareness of self or environment (are exceptions: sleep walking)
o High threshold of activity to external stimuli
o Simple mental activity (images, thoughts), tendency towards amnesia.
Very simple activity.
- REM sleep/paradoxical sleep
o Awareness of dream environment/dream self, in some cases also awareness of
sleeping self and physical movements (lucid dreams)
o Relatively low threshold of awareness of external stimuli
o Both spontaneous and intentional mental activity
(within the dream). Can have a dream, goals in the
dream aware of that you’re dreaming.
Levels of consciousness approach
- Assessing consciousness as a practical/ethical issue
- Come up with 2 axes, awareness is how much you know
what’s around you, and you.
- Vigilance is arousal, physiological response, fight or flight.
, - Locked in syndrome,
Lecture 2
Normal human sleep
- Behavioral definition: a reversible state of perceptual disengagement from and
insensibility to the environment
Contemporary view of sleep
- Sleep is an active and dynamic cyclical process
- Many physiological and psychological functions (possibly all) depend on sleep
o Hormones, development, immune system, gene expression, neurogenesis,
memory consolidation, emotion regulation…)
Historically
- Sleep – passive state, Mini-death, Oblivion, Soul travels
History of sleep research: antiquity
- Empedocles and Parmenides: “cooling” hypothesis of sleep
- Plato: theory of vision. Inward fire to stabilize inward motions in sleep
- Aristotle: sleep as a “seizure” produced by “exhalations” of ingested foods rising to the
brain to cool
Towards the modern era
- Hypnotoxin theory (19th century)
- Sleep is caused by accumulations of toxins
- Legendre and pieron
o Blood serum from sleep deprived dogs induced sleepiness in non-sleep deprived
dogs
- Sleep is intermediate state between wakefulness and death; wakefulness being
regarded as the active state of all the animal and intellectual functions, and death as
that of their total suspension
- Incapacitates you for some time
Discovery of biological rhythms
- Jean Jacques d’Ortous de Mairan 1729 : experiment with a heloptrope plant mimisa
pudica
o Plant continued its opening and closing activity even in absence of daylight.
- Its reacting, but rhythm is endogenous. They persist for a while and they readjust to
planetary rhythm
History of sleep research : EEG
- 1930s Harvard researchers record human sleep in EEEG
beginning of sleep science 1970s in Harvard
, Discovery of REM sleep
- Aserinsky and Kleitman (Chicago) observe a repeated pattern of rapid eye movements
(REMs) during sleep in young children
- They hypothesize that these periods represent periods of dreaming
o Why moving eyes in this patterns
- We look awake and have some people sleep and see if we can replicate it
- Predictably repeating, not random, seem to come back.
o Woke people up during REM and ask if they’re dreaming. So most of them
produced a dream report. Older papers will say REM sleep dream sleep
o We can predict when people r dreaming, tells how the mind works.
Themes in the course
- Sleep neurophysiology, circadian rhythms, functions of sleep (biological, cognitive) sleep
disorders, mind in sleep (dreaming, dreaming disorders, parasomnias)
o Sleep engineering, try to manipulate their dreams
How to study sleep
- Subjective estimation (questionnaires, interviews)
o Retrospective
o Prospective
- Objective measures
o Behavioural observation (e.g. video recording)
Watch people sleep, restless leg syndrome,
o Polysomnography
o Actigraphy
o Brain Imagery
o Other physiological measures
subjective estimation of sleep quality and length
- Retrospective
o Questionnaires, i.e. Pittsburgh Sleep Quality Index
o Interviews
o Pros: easy to obtain
o Cons: often unreliable, don’t correlate perfectly with objective measures, subject
to bias (e.g.I can never fall asleep!)
People have biases about how they sleep. People overestimate based on
how you sleep lately
- Prospective
o Sleep diaries
o Pros: Can be modified to target a specific sleep problem, e.g. insomnia, sleep-
walking, nightmares, etc.; eliminate some of the retrospective biases
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