Psych unit 4 AOS 1

Psychological constructs

An agreed upon description and understanding of psychological phenomena

that cannot be overtly measured or observed

What are psychological constructs used for?

• To understand or explain things that we believe exist but cannot

  • see,

  • touch,

  • or measure in any way.

• Researchers rely on

  • info provided by the individual,

  • behaviour that is shown

  • physiological changes

Normal waking consciousness (NWC)

• The ability to be aware of our internal and external stimuli

• The ability to voluntarily direct our awareness and attention

Altered states of consciousness (ASC)

Any state of consciousness that deviates from normal waking consciousness, in terms of marked differences in the levels of:

• awareness

• thinking

• sense of time, etc

Naturally occurring altered state of consciousness

A type of altered state of consciousness that occurs without intervention

• e.g. sleep

Induced altered state of consciousness

A type of altered state of consciousness that occurs due to a purposeful action or aid

e.g. meditation

What is sleep?

A regular and naturally occurring altered state of consciousness that involves a loss of awareness and disengagement with internal and external stimuli.

Sleep episode

The full duration of time spent asleep

Sleep cycle

A proportion of the sleep episode in which the sleeper progresses through stages of REM and NREM sleep

• on average: 90mins

Eye movements: REM vs NREM

NREM: Non-rapid eye movements

REM: Rapid, jerky eye movements

Brainwaves REM vs NREM

NREM: high amplitude, low frequency

REM: high frequency, low amplitude

• Beta-like brainwaves

Physiological arousal REM vs NREM

NREM: Decreases (heart rate, breathing)

REM: Increases (heart rate, breathing)

Muscles REM vs NREM

NREM: Some movement

REM: State of paralysis (muscle atonia)

Dreams REM vs NREM

NREM: Not likely to be vivid or recalled

REM: Common and likely to be recalled if awoken

Duration REM vs NREM

NREM:

• Approx. 80% of the night’s sleep

• decreases in proportion as the night progresses

REM:

• Approx. 20% of the night’s sleep

• increases in proportion as the night progresses

Purpose NREM vs REM

NREM: Physical restoration and memory consolidation

REM: Optimising neural pathways & emotional processing

NREM sleep definition

A period of sleep that is subdivided into three different stages, where the sleeper does not experience any rapid eye movement.

REM sleep definition

A period of sleep where the sleeper experiences rapid eye movement beneath closed eyelids.

NREM stage 1

• light stage of sleep

• easily awakened: have a low arousal threshold 

lower levels of bodily arousal, decrease in:

• heart rate

• respiration

• body temperature

NREM stage 2

• truly asleep

• more intense stimuli than stage 1 to awaken: higher arousal threshold

• Sleep spindles and k-complexes can be seen 

Physiological changes:

• Fewer body movements

• breathing→more regular

• heart rate → slower

• eye movements stop 

NREM stage 3

• deepest stage of sleep- highest arousal threshold 

• Muscles→ completely relaxed

• No eye movement

• Heart rate, blood pressure and body temperature → lowest and most regular

Physiological sleep measures

• the electroencephalograph (EEG)

• the electromyograph (EMG)

• the electro-oculograph (EOG)

Subjective sleep measures

• sleep diaries

• video monitoring

Hypnogram

A sleep graph that tracks the proportion of time spent in each stage of sleep, including awakenings throughout a sleep episode.

y axis- stage of sleep

x axis- duration of sleep

Electroencephalograph (EEG)

a device that detects, amplifies, and records the electrical activity of the brain.

• Electrical activity: communication of neurons in the brain. 

• Electrodes placed onto scalp- picks up signals & represent them in brain wave patterns.

How are brain waves measured?

Frequency- rate

Amplitude- height

Electromyograph (EMG)

A device that detects, amplifies and records the electrical activity of muscles.

• Records the strength of electrical activity occurring in the muscles

• Higher the level of muscular activity - more alert

Electro-occulargraph (EOG)

A device that detects, amplifies, and records the electrical activity of the muscles that move the eyes. 

• Electrodes- attached to areas around the eyes. 

• Used for REM/NREM measure. 

DARE acronym- used for physiological sleep measures

Detects

Amplifies

Records

Electrical activity

Sleep diaries

A record containing self-reported descriptions from an individual about their sleeping periods

• recorded over a period of time

• includes- duration of sleep, quality of sleep, thoughts and feelings before/after sleep, number of sleep disruptions, etc

Video monitoring

The use of camera and audio technologies to record an individual as they sleep

• Usually paired with physiological measures- gives validity to a phenomenon

Circadian rhythm

Biological and behavioural changes that occur as part of a cycle that lasts around 24 hours.

e.g. sleep wake cycle

Ultradian Rhythm

Biological and behavioural changes that occur in a cycle that lasts less than 24 hours.

e.g. REM and NREM sleep cycles

The Suprachiasmatic Nucleus (SCN)

An area of the hypothalamus that is responsible for regulating an individual’s sleep-wake patterns.

Where does the SCN receive information from?

• External cues: info from environment

  • e.g presence or absence of light

• Internal cues: info that originates within the body

  • e.g. expression or suppression of clock genes

SCN’s role in melatonin release

1. SCN receives external cues (lights off) and internal cues (clock genes).

2. SCN sends neural messages to the pineal gland-

3. Pineal gland produces and releases melatonin into bloodstream

4. Promotes feelings of calm and relaxation- therefore promotes sleep.

Melatonin

A hormone released by the pineal gland typically at night-time to induce sleep as part of the sleep-wake cycle.

Cortisol’s Role in the Sleep Wake-Cycle

A hormone released by the adrenal glands in the morning to increase alertness, wakefulness and maintain heightened arousal, thereby regulating the sleep-wake cycle. 

• High levels in the morning and low levels at night in the body.  

What is the sleep wake cycle regulated by?

biological mechanisms:

• Circadian rhythms

• ultradian rhythms

• the SCN

• melatonin

Sleep Wake Cycle

A type of circadian rhythm – 24-hour-cycle made up of time spent sleeping and time being awake and alert.  

• 2 biological mechanisms that help regulate sleep-wake cycle:

  • suprachiasmatic nucleus

  • melatonin. 

neonatal period characteristics of sleep (1-15 days)

Sleep duration: ~16 hrs.

Sleep episode: ~50% REM, ~50% NREM.

• brief awakenings during the sleep episode

infancy period characteristics of sleep (3-24 months)

Sleep duration: ~13.5 hrs.  

Sleep episode: ~35% REM, ~65% NREM. 

Compared to adults

• brief awakenings during the sleep episode

• greater amount of sleep cycles

• Shorter sleep cycles

Childhood characteristics of sleep (2-14 years)

Sleep duration: ~11 hrs.

Sleep episode: ~20% REM, ~80% NREM. 

Adolescence characteristics of sleep (14-18 years)

Sleep duration: ~9 hrs.

Sleep episode: 20% REM, 80% NREM.

- DSPD: biological delayed sleep onset by 1–2 hrs 

Adulthood characteristics of sleep (18-75 years)

Sleep duration: ~7-8 hrs.

Sleep episode: 20% REM, 80% NREM.

Compared to infants

• more likely to experience one full sleep episode- less wakeups

• less sleep cycles

• longer sleep cycles

Old age characteristics of sleep (75+ years)

Sleep duration: ~6 hrs.

- Sleep episode: 20% REM, 80% NREM.

- ASPD: biological shift forward in sleep-wake cycle. 

- Wake up more frequently throughout the night.

- Amount of N3 sleep decreases, replaced mostly by N2 sleep.

Explanations for Notable Differences in Sleep Across the Lifespan 

Sleep requirements change because physical and cognitive needs change over time. 

• REM = important for (replenishes) brain and cognitive development and rest.

• NREM = important for (replenishes) physiological rest and development.

Neonatal period and infancy- explanation for sleep characteristics

• No established circadian rhythm – sleep distributed across the full 24 hour day. 

• Significant time spent in REM sleep due to rapid brain development.

• Growth, development, rapid physiological changes = infants begin to have a fairly consistent circadian rhythm. 

Childhood- explanation for sleep characteristics

Time spent in REM sleep starts to reduce as the pace of brain development steadies.

Adolescence- explanation for sleep characteristics

• Social factors decrease proportion of sleep – waking up early for school, social commitments during the nighttime. 

Adulthood and old age- explanation for sleep characteristics

Lower levels of sleep due to:

- Ill health and increase prevalence of sleep disorders.

- Reduced amount of cognitive and physical growth.

Partial sleep deprivation

inadequate sleep based on an individual’s needs (quantity/quality)

Total sleep deprivation

when an individual has no sleep within a 24-hour period

Effects of partial sleep deprivation

Affective effects

Behavioural effects

Cognitive effects

Affective effects of sleep deprivation

Amplified emotional responses

• Increased irritability

• Depressed mood

• Heightened anxiety

• Decreased motivation

Behavioural effects of sleep deprivation

The changes in actions and the ability to control them that arise from sleep deprivation

• reduced motor control

• reduced spatial awareness

• slower reaction times

• microsleeps

Cognitive effects of sleep deprivation

The changes in mental processes that arise from sleep deprivation

• decreased ability to concentrate and direct attention

• poorer performance/increased error rates on tasks involving problem solving or logical reasoning

• Increased forgetfulness

• Illogical or irrational thoughts

• Difficulty completing simple repetitive tasks

Partial Sleep deprivation compared to BAC

The effects of a BAC level of 0.05 are roughly equivalent to 17 hours of sleep deprivation.

Total Sleep deprivation compared to BAC

The effects of a BAC level of 0.10 are roughly equivalent to 24 hours of sleep deprivation

Affective effects of sleep deprivation compared to blood alcohol concentration

Can both impact a person’s affective functioning

Sleep deprivation: negative effects

Alcohol: range of effects

• happy

• excited

• angry

• sad

Cognitive effects of sleep deprivation compared to blood alcohol concentration

Both have cognitive impairments that include:

• reduced speed in processing and understanding information

• decreased ability to reason and problem solve

• greater difficulty making sense of the world