Chapter 7 Summary Notes

Psychological Construct

Something that cannot be objectively observed or measured through the collection of data, but it is widely understood to exist.

Consciousness

An awareness of our own thoughts, feelings and perceptions (internal thoughts) and our surroundings (external stimuli) in the environment.

• Selective

• Personal

• Continuous

• Constantly changing

Researchers use to measure consciousness:

• Information provided by the individual (e.g. self-report)

• Behaviour that is demonstrated (e.g. responses during experimental research)

• Physiological responses that can be measured (e.g. recording brain activity)

State of Consciousness

An individual's level of awareness of internal and external stimuli at any given moment.

Continuum of Awareness

1. High level of awareness - highly focused and actively aware (concentrating on a test)

2. Medium level of awareness (daydreaming)

3. Low levels of awareness (sleep)

4. Complete lack of awareness (coma)

Normal Waking Consciousness (NWC)

Awareness of your thoughts, feelings, perceptions and behaviour from internal and external events (the surrounding environment)

Altered States of Consciousness (ASC)

A state other than normal waking consciousness in terms of awareness, thoughts, feelings and behaviour. 

Can be naturally occurring or induced.

Sleep

A regularly occurring ASC (reversible) that typically occurs naturally and is primarily characterised by partial or total suspension of conscious awareness.

Characteristics of Sleep

1. Level of awareness - some, albeit very little, awareness of our external environment

2. Fewer content limitations - let go of conscious control of our thoughts

3. Controlled and automatic process - performing other tasks is probably impossible

4. Perceptual and cognitive distortions - attention to sensory stimuli is lowered, thoughts are disorganised and unrealistic

5. More or less emotional awareness - emotions are more or less intense during sleep

6. Less self control - monitoring our behaviour and self control is lowered

7. Distorted time orientation - ability to perceive the speed and how much time has passed may be affected

Sleep as a Psychological Construct

Different types of sleep are associated with different levels of alertness and experiences of consciousness. 

Researchers use to measure sleep:

• Information provided by the individual (e.g. self-report)

• Behaviour that is demonstrated (e.g. responses during experimental research)

• Physiological responses that can be measured (e.g. recording brain activity)

REM and NREM Sleep

A complete sleep cycle consists of a period of NREM sleep with transitions between its 3 stages and a period of REM sleep. 

A sleep cycle is a proportion of the full period of time that a person spends asleep.

Each cycle is repeated about 5 or 6 times each night, depending on the duration of the sleep cycle. 

First third of the night is the time when the deepest sleep usually occurs.

REM sleep periods increase as the night progresses and is longest in the last third of the night.

Brief episodes of wakefulness tend to occur in later cycles with transitions between NREM and REM -> considered part of a sleep episode rather than waking time.

NREM

3 distinct stages (N1, N2 and N3)

Decline in physiological activity (brain and body)

Around 75-80%

Stage 1 is the lightest and stage 3 is the deepest

Brain waves get slower and bigger, breathing and heart rate slow down, blood pressure drops.

N1

Begins in the first sleep cycle

A period of relatively light sleep

Easiest stage to be woken up from

Decrease in heart rate, breathing, body temperature and slow, rolling eye movements

Overall slowdown of brain waves from their daytime wakeful patterns

N2

Light sleep (deeper than N1)

Continued slowing of heart rate, breathing, muscle activity, body movements, body temperature and eye movements stop

Brain waves slow further but may be marked by brief bursts of electrical activity (sleep spindles), typically occurring every 3-6 seconds during N2.

First cycle lasts for about 10-25 minutes, lengthens with each successive cycle, constituting about half of the total sleep episode

N3

Deepest sleep, extremely difficult to be woken up from

Heart rate and breathing slow to their lowest levels, muscles completely relaxed, barely any movement and no eye movements

Brain waves become even slower, with the largest and slowest brain waves, occurring more than 50% of the time

In the first sleep cycle a person may spend between 20 and 40 minutes in N3

REM

Brain is most active

Around 20-25%

Sleep paralysis

Brain wave pattern similar to those during alert wakefulness

Faster HR, BP rises, breathing is shallow

Most dreaming occurs during REM, final dream of the night can be remembered

Sleep periods lengthen and occur closer together as a sleep episode progresses

Hypnogram

The measurement of sleep is shown as a hypnogram (sleep graph)

Shows that NREM and REM sleep periods alternate throughout a typical episode in a cyclical way.

If sleep is a psychological construct, how do we measure it?

Measurements of physiological responses enable researchers to obtain quantitative data on bodily processes and changes that occur as we fall asleep, during sleep itself and as we awaken from sleep.

Data includes information about:

• The electrical activity of the brain, eye movements, and the body’s muscles tone or tension

Other physiological responses such as heart rate, body temperature, respiration, the amount of oxygen in the blood, body position, leg movements or snoring noises.

Electroencephalograph (EEG)

A method of studying brain waves produced during sleep

Detects, amplifies and records electrical activity in the brain (in the form of brain waves)

Tiny electrodes placed on the outside of the skull

Shows the frequency and amplitude of brainwave activity (frequency - the number of brainwaves per second, amplitude - the size of peaks and troughs in brain activity

Electro-oculogram (EOG)

A method of measuring eye movements or eye positions during sleep

Detects, amplifies and records electrical activity in the muscles surrounding the eye

Measures changes in voltage as the eyes move and rotate around the sockets

Can determine if we are in a NWC or ASC and if we are in REM or NREM

Most commonly used to measure changes in eye movements over time during different types and stages of sleep and while dreaming

Electromyograph

A method of studying the electrical activity of muscles produced during sleep

Detects, amplifies and records electrical activity created by active muscles (muscle tension)

Indicated changes in electrical activity in muscles that accompany changes in SOC

Advantages and Limitations of Physiological Measurements

Advantages:

• Data is objective and reliable

• Data is consistent and easily compared

• Data can be measured automatically

Limitations:

• Does not record subjective data (a person’s private and personal conscious experience - thoughts and feelings)

• Does not take into account personality

• Does not account for extraneous variables (changes in physiological events may be due to other reasons besides a change in SOC)

Video Monitoring

Video cameras to monitor and record externally observable physiological responses throughout a sleep episode, including behaviours when falling asleep and when waking

• Changes in posture or body position

• Amount of tossing and turning

• Sleep-related breathing problems

• What happens when awakening from a nightmare 

• Behaviours associated with sleepwalking

Sleep Diary

A subjective ‘log’ used to self-record and self-report sleep

Often used in conjunction with physiological measures to support the assessment of sleep disturbances or disorders, particularly their nature, severity and possible causes

Objective VS Subjective Data

Subjective data is often biased, can vary from person to person, day to day from the same person, and is not always accurate.

An objective measure such as an electronic recording device like an EEG or EMG is impartial and not subject to personal opinion or interpretation.

Newborn and Infants

16-18 hours, drops to around 14-15 hours by 12 months

Around 50% is REM

REM includes lots of facial movements and possible arm and leg movements

Sleep onset occurs through REM and each sleep episode consists of 1 or 2 cycles -> circadian rhythm not fully developed

By 3 months NREM-REM cycles are more regular, sleep onset is in N1

By 6 months total sleep time reduces slightly, full NREM cycles, muscles paralysis of REM sets in

By 12 months, sleep is 14-15 hours per day with a single sleep episode in the evening.

Young Children

Toddler= 1-2 years, 11-14 hours, REM 25-30%, NREM 70-75%

Pre-schooler= 3-5 years, 10-13 hours, REM 25%, NREM 75%

School-aged children= 6-13 years, 9-11 hours, REM 20%, NREM 80%

Greater percentage of sleep in N2 and N3

Half of NREM sleep is N3 but decreases age 10

Often skip first REM sleep period

Sleep shifts to earlier in the evening as daytime naps are dropped

Early to late childhood years, sleep shifts to later in the evening

Adolescents

14-17 years, 8-10 hours, REM 20%, NREM 80%

First REM period is unlikely to be skipped

Amount of N3 progressively declines and N2 increases

By late adolescence, N3 has decreased by nearly 40% since early childhood

Adolescents tend to get less sleep than they need to function due to change in their sleep-wake cycle that delays its onset by 1-2 hours and school-related requirements

Staying up late during the week and even later on the weekends and sleeping in late can impact quality of sleep

Adults

18-25, 7-9 hours, REM 20%, NREM 80%

Same for 26-64 year olds

Average 8 hours of sleep

Gradual loss of N3

N3 declines at a rate of 2% per decade between 20-60

Young adults may experience brief awakenings, but are usually minor and occur close to transitions

Preference for earlier sleep time

Sleep patterns can alter due to tertiary study, work requirements, social schedules, increased independence, caring for infants and children, development of health problems and changing family dynamics

Elderly

Over 65, 7-8 hours, REM 18-20%, NREM 80-82%

More awakenings associated with the decline of N3

Sleepier in the earlier evening and wake earlier in the morning

Sleep-wake cycle is shifted forward

Decrease in melatonin levels

Other factors include medical problems, decreased mobility leading to a reduction in exercise, irregular meal times, medication use, change of living arrangements and bereavement.

N3 sleep may not occur at all, replaced with N2

Increase in the time taken to fall asleep

Shorter total sleep maybe due to inability to obtain sleep rather than a reduced need for sleep.

Circadian Rhythm

Physiological, psychological or behavioural changes that occur a part of a cycle with a duration of approximately 24 hours.

Causes us to feel more or less alert at certain points of the day.

Controlling our sleep-wake cycle, release of hormones and regulation of body temperature

Light is the main environmental cue that influences the sleep-wake cycle.

Sleepiness is highest at night and lowest in the day

Influenced by environmental time-giving stimuli (exogenous) that keep it in sync with the 24-hour day-night cycle.

Ultradian Rhythm

Physiological, psychological or behavioural changes that occur as part of a cycle shorter than 24 hours.

• Sleep cycles (around 90 minutes)

• Heartbeat

• Respiration 

• Hunger

May last from a few minutes to a few hours, cycle repeatedly over the course of a day

Suprachiasmatic Nucleus

An area of the hypothalamus, considered to be the master biological clock that regulates the timing and activity of the sleep-wake cycle.

SCN receives information about the amount of light from the eyes → signals nearby pineal gland to produce or secrete more or less melatonin in relation to light intensity → amount of melatonin present in the blood is associated with alertness (higher melatonin level = greater drowsiness and vice versa)

Melatonin

When the eyes detect no light at night, melatonin is released.

Melatonin induces drowsiness.

When the SCN detects light in the morning, it inhibits the release of melatonin

Artificial lighting can be bright enough to impede the release of melatonin

Sleep Deprivation

Partial sleep deprivation is experienced when a person does not get the amount of sleep they need (poor quantity sleep) or are deprived of one particular stage of sleep (poor quality sleep)

Partial sleep deprivation is having some sleep in a 24 hour period, but not enough.

Total sleep deprivation is going without sleep for a 24 hour period.

Causes of Partial Sleep Deprivation

• Consuming caffeine, food, drugs or alcohol

• Work/school requirements

• Failing to wind down before bed

• Stress

• Medical conditions

• Uncomfortable sleeping environment

• Social influences

• Sleep disorders (circadian rhythm sleep disorders, delayed sleep phase syndrome, advanced sleep phase disorder)

Effects of Partial Sleep Deprivation

Affective (emotions): interfere with emotional regulation and reactivity, inability to control emotions, too quick emotional reactions, interferes with our ability to process and perceive emotional responses

Behaviour: interfere with ability to control behaviours, increased risk taking/impulse behaviour, slowed reaction times, lack of energy, tasks take longer to complete, lowered work efficiency, increased number of mistakes, hyperactivity/increased misbehaviour

Cognitive: reduced concentration and ability to stay focused, reduced ability to maintain sustained attention/inability to divide attention, trouble with memory, decreased problem solving/decision making, poor judgement, lack of motivation, learning difficulties, slower thinking

Impact on Quality of Sleep

Loss of NREM: Being deprived of NREM may interfere with the growth hormone being released. Loss of NREM may prevent restoration of the body and its ability to replenish energy supplies.

Loss of REM: poor concentration, poor memory and learning, irritability, tendency to hallucinate, loss of motor coordination

BAC vs Sleep Deprivation - effects on consciousness

Cognition: changes in thinking processes

Affective: changes in emotional state and functioning

Comparing Sleep Deprivation with BAC

17 hours without sleep = 0.05 BAC

24 hours without sleep = 0.10 BAC

Cognitive effects: impaired in a similar way

Affective effects: can be different - sleep deprived: always negative emotions, under the influence of alcohol: can be negative or positive

Circadian Rhythm Sleep Disorders

A group of sleep disorders involving sleep disturbance that is primarily due to a mismatch between an individual’s sleep-wake pattern and the pattern that is desired or required.

May be caused by:

• Naturally occurring change or malfunction

• Mismatch between an individual’s sleep-wake cycle and the day-night cycle of their physical environment

• Mismatch between an individual’s sleep-wake cycle and the sleep-wake scheduled required of them

Delayed Sleep Phase Syndrome (DSPS)

A condition in which the major sleep episode is delayed in relation to the desired sleep time or what is considered a conventional time. 

Natural tendency to go to sleep later and therefore wake up later than what is normal according to society’s clock.

The onset of the entire sleep-wake cycle is significantly delayed, often by 2 or 3 hours and in some cases much longer.

Prominent symptoms include:

• Sleep onset insomnia

• Difficulty awakening at the desired or necessary time

• Excessive sleepiness

Advanced Sleep Phase Disorder

A persistent disturbance of the sleep-wake cycle characterised by advance of the major sleep episode to an earlier time compared to desired or conventional sleep times.

Results in compelling evening sleepiness, early sleep onset, and awakening earlier than the desired or necessary times.

Going to bed and waking up too early because of their difficulty or inability to remain awake or asleep until they want to. 

Symptoms:

• Falling asleep early

• Waking up early

Shift Work Disorder

A circadian rhythm sleep disorder that occurs as a result of work shifts being regularly scheduled during the usual sleep period.

Impacts:

• Safety concerns

• Partial sleep deprivation

• Insomnia 

• Excessive sleepiness

• Mood swings, mental health problems and physical illness

Bright Light Therapy

Used to treat people suffering from circadian rhythm sleep disorders by resetting the body’s internal clock.

Involves timed exposure of the eyes to intense but safe amounts of light.

Aimed at shifting an individual’s sleep-wake cycle to a desired schedule, typically the day-night cycle of their physical environment.

Sleep Hygiene

Practices that improve and maintain good sleep at night and daytime alertness.

• Establish regular sleep onset and wake schedules

• Minimise exposure to light before bed and flood yourself with light in the morning

• Associate your bed and bedroom with sleep

• Avoid stimulating activities before bed

• Avoid napping during the day

• Avoid stimulants too close to bedtime

• Improve your sleep environment (clean, dark, quiet, right temperature)

• Establish a wide-down bedtime routine

Daylight

Exposure to sunlight helps ensure that we are awake during the day and asleep at night.

Primary zeitgeber for the human circadian rhythm

Blue light: providing light exposure to delay the release of melatonin (inhibition of melatonin reducing the quality and quantity of sleep = poor mental and physical wellbeing). However, blue light can be used to keep a person alert while improving performance and mood, such as by improving student learning in schools, the performance of indoor employees or the mood of people in hospitals and nursing homes.

Temperature

Regulated by a circadian rhythm and is linked to the sleep-wake cycle. Body temp begins to decrease in the early evening, with sleep onset occurring when core body temperature is at its greatest rate of decline, and lowest body temp is about 2 hours after sleep onset. Skin warming helps to initiate sleep by using bedding to provide warmth before and during sleep.

Eating and Drinking Patterns

Sleep-wake patterns can be influenced by what you eat and drink and when you eat and drink. The circadian rhythm prepares the body to be efficient at digesting food during the day when we are more active, however if the timing is altered to the dark phase of the 24-hour cycle, the meal times are now misaligned with the routine light-dark cycle. This can disrupt and cause a shift in normal functioning of the body clock. 

Sleep and Mental Wellbeing

Sleep hygiene -> good quality sleep of an adequate quantity -> positively impacts mental wellbeing