SLEEP: (WK6):

CONSCIOUSNESS:

  • mind-body problem

  • levels of consciousness

    • minimal consciousness = a low level of sensory awareness that occurs when the mind inputs sensations and may output behaviour

    • full consciousness = you are able to know and report your mental state

    • self consciousness = distinct level of consciousness where the person’s attention is drawn to the self as an object

BIOLOGICAL CLOCK:

  • behaviour is not driven just by external cues

  • rhythms are endogenous 

  • bio clock = neural system that times behaviour

CIRCADIAN RHYTHM:

  • all animals have an endogenous circadian rhythm, operates approx 24 hour cycle

    • can differ from person to person

    • changes with age

    • keep our internal workings in phase with the outside world

    • zeitgeber = term used to describe any stimulus that resets circadian rhythm e.g. light, exercise, meals and temp

RHYTHM OF WAKING AND SLEEP:

  • jet lag refers to the disruption of the circadian rhythms due to crossing time zones

    • mismatch between internal and external times, sleepiness

  • travelling west = ‘phase delays’

  • travelling east = ‘phase advances’

  • light treatment for SAD (seasonal affective disorder)

THE SUPRACHIASMATIC NUCLEUS:

  • SCN = part of the hypothalamus and the main control centre of the circadian rhythms of sleep and temp

  • damage to SCN results in less consistent body rhythms, no longer synced to light and dark environment

  • single cell extracted from the SCN and raised in tissue culture continues to produce action potential in a rhythmic pattern

  • light resets the SCN vis small branch of the optic nerve

  • travels directly from the retina to the SCN

  • the retinohypothalamic path comes from a special population of ganglion cells - own photopigment called melanopsin

  • the cells respond directly to light and do not require input from rods or cones

GENES, PROTEINS & CIRCADIAN RHYTHM:

  • two types of genes responsible for generating circadian rhythm:

    • period = protein called PER

    • timeless = protein called TIM

  • increase activity of certain types of neurons in the SCN that regulate sleep and waking

MELATONIN:

  • SCN regulates pineal gland, an endocrine gland located posterior to the thalamus

  • pineal gland secretes melatonin, a hormone that increases sleepiness

  • usually begins 2-3 hours before bedtime

  • feeds back to the bio clock through its effects on receptors in the SCN

SLEEP:

  • functions of sleep:

    • energy conservation, restoration of the brain and body, memory consolidation

  • sleep enables restorative processes,

    • proteins rebuilt in the brain

    • energy supplies replenished

  • moderate sleep deprivation results in impaired concentration, irritability, hallucinations, unpleasant mood & decreased immune system

  • caffeine increases arousal by blocking the receptors for adensine

  • animals increase sleep in food shortage = hibernate

SLEEP STUDY:

  • use a electroencephalograph (EEG) 

  • compare brain activity at different times during sleep

  • polysomnograph = combination of EEG and eye-movement records

STAGES OF SLEEP:

  • stage 1

    • sleep has just begun, EEG dominated by low voltage waves

    • brain activity begins to decline

  • stage 2

    • sleep spindles = 12- to 14-Hz waves during a burst that lasts at least half a second

    • k-complex = high amplitude negative wave followed by a smaller positive wave

  • stage 3 & 4

    • consitute slow sleep waves (SSW) 

    • large, slow amplitude wave

    • slowing of heart rate, breathing rate and brain activity

    • highly synchronised neuronal activity

  • REM

    • rapid eye movement

    • EEG waves are irregular, low voltage and fast

  • sequence goes: 1, 2, 3 & 4 in order, before cycling back from 4, 3 , 2 and then REM (90 mins)

  • stage 3 & 4 predominate early night, REM is later (associated with dreaming)

REM:

  • activity increases in the pons (triggers on set of REM sleep) and limbic system (emotional systems), parietal cortex & temporal cortex

  • cells in pons send messages to the spinal cord which inhibit motor neurons that control the body’s larger muscles

    • prevents motor movement during sleep → sleep paralysis

  • REM is regulated by serotonin & acetylocholine

  • 1/3 time asleep, 1/5 in REM

WHY:
FREUD’S PSYCHOANALYTIC THEORY:

  • wish fulfillment = gratification of our unconscious desires and needs

    • sexual & aggressive that are too unacceptable to be spoken aloud

    • manifest content = surface story that dreamer reports

    • latent content = dreams disguised psychological meaning

    • dream work = process by which a dreams latent content is transformed into manifest content

ACTIVATION-SYNTHESIS THEORY:

  • dreams do not have a function, product of REM neural activity

  • brain bombarded with random neural activity during REM sleep

  • explains why dreams are so bizarre

PROBLEM-SOLVING DREAM MODEL:

  • dreams are not constrained by reality they can help us find creative solutions to our problems

COGNITIVE-PROCESS DREAM THEORIES:

  • focuses on process of how we dream, proposes that dreaming and waking thought are produced by the same mental systems

SLEEP PROBLEMS:

  • insomnia 

    • sleep disorder caused by pain, stress, noise or medication

    • can also result from other disorders

    • dependency on sleeping pills can also result in insomnia

  • night terrors

    • intense anxiety where one wakes from a dream screaming

  • sleep talking

  • sleep walking