Consciousness and Sleep

Consciousness

• Central to our reality and sense of self.

• Defined as awareness of:

  • Internal events (thoughts, feelings, perceptions).

  • External stimuli (surroundings) at any moment.

• Psychological construct

Sense of self

• Developed through being aware of what

  • we are doing,

  • why we are doing it

  • and the awareness that others are probably observing, evaluating and reacting to it.

Normal Waking Consciousness

• A state associated with being aware of our internal and external environments.

• Experienced during everyday activities when awake. and have a regular level of awareness.

Altered State of Consciousness

• Any state that differs in awareness from normal waking consciousness.

• Levels of awareness are either lower or higher than in normal waking consciousness.

Types of Altered State of Consciousness

• Naturally occurring

• Induced

Naturally Occurring Altered State of Consciousness

• Occur without any external influence, such as sleep or state of fatigue.

Induced Altered State of Consciousness

• Brought about on purpose, such as

  • alcohol-induced states

  • an anaethetised state for an operation

  • meditative state.

Sleep

• Naturally occurring and reversible altered state of consciousness.

• Characterized by reduced awareness and responsiveness to external surroundings.

• Unique brain wave activity and distinguishable physiological changes.

• Differentiates from other altered states (e.g., brain injury, substance use).

• Considered a psychological construct as part of consciousness.

Types of Sleep

• Rapid Eye Movement (REM) Sleep.

• Non-Rapid Eye Movement (NREM) Sleep.

Sleep Cycles

• An average person experiences about five sleep cycles during an eight-hour sleep episode.

• Each cycle lasts approximately 90 minutes.

• Features repetitive patterns of REM and NREM sleep.

Non-Rapid Eye Movement (NREM) Sleep.

• Characterized by a progressive decline in physiological activity.

• Consists of three distinct stages.

• Takes up around 80% of a sleep episode in people of school age and older.

NREM Stage 1 (N1)

• A transitional phase between wakefulness and sleep, is light sleep.

• Physiological responses begin to slow down,

  including brain activity, heart rate and body temperature.

• The period when a person "dozes off" and can be easily woken

• Limited time spent in N1 as sleep episode progresses

• Quickly moves into NREM Stage 2 if undisturbed for a couple of minutes in this stage.

NREM Stage 2 (N2)

• Also considered light sleep, during which

  physiological responses continue to slow down.

• A person still wakes relatively easily

• Bursts of brain activity help resist being woken by environmental stimuli (e.g., noises)

• The stage of sleep that is experienced the most throughout a sleep episode.

NREM Stage 3 (N3)

• This stage is deep sleep, during which physiological responses are at their slowest

• A person is most difficult to wake up during this stage.

• Also known as 'slow-wave sleep' due to very slow brain activity

• Experienced more in the first half of the night than the second half

• May not occur in the last one or two sleep cycles

• Different ages spend varying amounts of time in this stage.

• Thought to be a period when the body repairs itself during NREM sleep

Rapid Eye Movement (REM)

• Eyes make quick darting movements behind closed eyelids

• Physiological activity increases: brain activity resembles wakefulness, heart rate and breathing rate increase

• Voluntary muscles are seemingly paralyzed, twitching only intermittently

• Most vivid and memorable dreams occur during […] sleep

• […] periods occur at the end of each sleep cycle

• […] periods get longer and closer together as the sleep episode progresses

• More […] sleep occurs in the second half of sleep than in the first half

Electroencephalography (EEG)

• A technique that Detects, Amplifies and Records the Electrical activity of the brain.

EEG Process

• During this, electrodes are attached to the person's scalp, through a cap, or a headset.

• The electrodes detect the synchronized electrical impulses of many neurons communicating in the cortex near the scalp surface.

• Wires connected to the electrodes transmit this data to an instrument

• The instrument amplifies the signals to a readable level and sends them to a computer.

• The computer records the brain wave patterns, which are then interpreted by a specialist.

Main types of brain waves

• Beta

• Alpha

• Theta

• Delta

Characteristics of brain waves

• Frequency

• Amplitude

Frequency

• indicates speed/activity level

Amplitude

• height of peaks and troughs

General patterns of brain waves

• Slower frequency waves

• Faster frequency waves

Slower frequency waves

• prevalent when tired, relaxed, or asleep

Faster frequency waves

• prevalent when awake and alert

Beta Brain Wave

• Frequency

  • Highest

• Amplitude

  • Lowest

• State

  • Normal waking consciousness.

  • Awake, alert and focused.

  • High environmental stimulation.

  • Brain working on several things at once.

Alpha Brain Wave

• Frequency

  • High

• Amplitude

  • Low

• State

  • Lower alertness.

  • Awake but relaxed.

  • Quiet and calm.

  • Drowsy.

  • Eyes closed.

  • Low environmental stimulation

Theta Brain Wave

• Frequency

  • Low

• Amplitude

  • High

• State

  • Low alertness.

  • Light sleep.

  • Senses withdrawn from the external environment.

  • Deep meditation.

Delta Brain Wave

• Frequency

  • Lowest

• Amplitude

  • Highest

• State

  • Lowest alertness.

  • Deep N3 sleep.

  • Dreamless sleep.

Electro-oculograph (EOG)

• A device that detects, amplifies and records electrical activity in the muscles that allow the eye to move.

• Useful for determining if a person is in REM (Rapid Eye Movement) or NREM (Non-REM) sleep.

Uses of EOG

• Determine the onset of sleep

• Identify the stages and types of sleep

• Detect changes in eye movement

Electromyography (EMG)

• A technique that detects, amplifies and records the electrical activity of the skeletal muscles.

• Electrodes are attached to the skin, typically around the jaw, legs, or other body parts.

• Measures muscle tension and movement.

Uses of EMG

• Detect abnormal movements during sleep, such as:

  • Tossing and turning

  • Teeth grinding (bruxism)

  • Periodic limb movements

• These abnormal movements can indicate sleep disorders.

Sleep Diaries

• A subjective, self-report tool used by people to track their own sleep and wake cycles.

• The purpose is to identify any patterns or habits that may be contributing to the sleep issues.

• Provide the sleep specialist with a personal and subjective account of the quantity and quality of the person's sleep.

What Is included in Sleep Diaries

• spaces to record the time of sleep onset,

• waking time,

• how the person felt upon waking and any disturbances to sleep such as:

  • periods of waking,

  • unusual behaviours such as sleep walking or night terrors.

• Things that can impact sleep patterns

Things that can impact sleep patterns

• Caffeine intake over the day

• Any naps taken and

• Exercise completed.

Video Monitoring

• Used to collect qualitative visual and audio information about a person’s sleep during a sleep study.

• Used alongside EEGs, EOGs and EMGs

• Can validate the data collected by these devices to show exactly what activity is occurring while a person is asleep such as:

  • sleeping positions,

  • specific movements,

  • laboured breathing,

  • sleep talking

  • teeth grinding.

• Useful for children who:

  • Have trouble verbalizing their sleep experience

  • Are too young to complete a sleep diary

PROS - Sleep Diaries & Video Monitoring

• Visual data

• Confirms anything you think you may/may not be doing during sleep

• Finding issues & change behaviours from the issues

• Double checking information

CONS - Sleep Diaries & Video Monitoring

• May not remember (diary)

• Creepy

• Not sleeping in your own bed (EV)

• Connected to so many electrodes & being uncomfortable

Regulating Sleep-Wake Patterns

• The regular patterns of the sleep-wake cycle can be explained by the precise functioning of several biological mechanisms, including the:

  • Circadian rhythm,

  • Ultradian rhythms,

  • The suprachiasmatic nucleus in the brain and

  • The hormone melatonin.

Circadian Rhythms

• Biological processes in all animals that coordinate the timing of activity of body systems over a 24-hour period.

• Allow for optimised functioning at certain time points over the course of 24 hours.

How Circadian Rhythms Allow For Optimized Functioning

• This is done by controlling our sleep–wake cycle, release of hormones and regulation of body temperature.

Circadian Rhythms in Humans

• Circadian rhythms follow a 24-hour period

• Most people sleeping at night and being awake and active during the day.

Ultradian Rhythms

• Biological processes that coordinate the timing of activity of body systems over periods of less than 24 hours.

• Duration ranges from a few minutes to a few hours, allowing multiple cycles per day.

• Includes processes like

  • heart rate,

  • digestion,

  • blood pressure,

  • certain hormone secretions

  • appetite.

Suprachiasmatic Nucleus

• Part of the brain's hypothalamus.

  • It functions as the master body clock.

• This sends signals at specific times within a 24-hour cycle.

  • These signals regulate various bodily activities, ensuring a consistent daily schedule.

• Can independently maintain an approximately 24-hour cycle.

• It is influenced by external cues called zeitgebers.

• Particularly sensitive to light.

  • This sensitivity links the human circadian rhythm closely to the day-night cycle.

Detection of Light

• Light-sensitive neurons in the retinas of the eyes detect incoming light and send messages to the brain’s suprachiasmatic nucleus about the amount of light in the surroundings.

Light detection at Night

• When the eyes detect no light, the suprachiasmatic nucleus sends a signal to the pineal gland in the human brain.

• This results in the pineal gland releasing melatonin.

• The increased release of melatonin by the pineal gland at night-time induces sleepiness and decreases cell activity.

• This process ensures that our sleep is connected to night-time.

Light detection at Day

• When the eyes detect more light, the suprachiasmatic nucleus sends inhibitory messages to the pineal gland, resulting in the inhibition of melatonin release by the pineal gland.

• The result is that a person does not feel drowsy, and therefore wakefulness is promoted during the day.

Melatonin

• A hormone that induces drowsiness.

Why Do We Sleep?

• Necessary for repair and restoration of the body and mind

  • Repairs tissues

  • Replenishes neurotransmitters

  • Removes waste products

• Serves as an adaptive function

  • Allows the body to conserve energy

  • Provides safety during times of potential danger (e.g. night-time for humans)

• Allows for information processing and consolidation

  • Aids in memory

  • Prepares the mind for the new day

Sleep across the lifespan - Newborn

• 0 - 3 Months

• Recommended Hours

  • 14 - 17 hours

• REM

  • 50%

• NREM

  • 50%

• Require the highest amount of sleep for rapid growth and development (REM may boost brain growth, and help consolidate learning and memory)

• Muscle twitches (NREM) and muscle relaxation (REM) may develop their sensory motor systems

Sleep across the lifespan - Infant

• 4 - 11 Months

• Recommended Hours

  • 12 - 16 hours

• REM

  • 30 - 40%

• NREM

  • 60 - 70%

• They begin to sleep for longer periods at a time as their circadian rhythm develops a more regular sleep pattern following day–night cycles.

Sleep across the lifespan - Children

• 1 - 13 years

• Recommended Hours

  • 4 - 14 hours

• REM

  • 20 - 30%

• NREM

  • 70 - 80%

• REM will decrease

• Napping will decrease

• Sleep onset will start earlier and eventually will get later.

Sleep across the lifespan - Adolescents

• 14 - 17 years

• Recommended Hours

  • 8 - 10 hours

• REM

  • 20%

• NREM

  • 80%

• They experience a delay in the circadian rhythm because of a hormonally determined shift in melatonin release to 1–2 hours later than other age groups.

• This can cause a preference for a later bedtime, resulting in fewer hours of sleep than needed because of early waking for school.

• Increasing school-related requirements, increasing independence and easy access to constant entertainment and social networks also contribute to delayed bedtime.

Sleep across the lifespan - Young Adult

• 18 - 25 years

• Recommended Hours

  • 7 - 9 hours

• REM

  • 20%

• NREM

  • 80%

• Sleep patterns change due to:

  • tertiary study

  • work

  • social schedules

  • increased independence

• N3 sleep decreases and is replaced by N2 sleep later in adulthood.

• Melatonin concentrations also begin to decline after puberty.

Sleep across the lifespan - Adult

• 26 - 64 years

• Recommended Hours

  • 7 - 9 hours

• REM

  • 20%

• NREM

  • 80%

• Sleep patterns change due to:

  • Caring for infants and children

  • Changing work and social requirements

  • Development of health problems

  • Changing family dynamics (e.g., balancing work with parenthood)

• N3 sleep decreases and is replaced by N2 sleep later in adulthood.

• Melatonin concentrations continue to decline over adulthood.

Sleep across the lifespan - Elderly/Older Adult

• 65+ years

• Recommended Hours

  • 7 - 8 hours

• REM

  • 18 - 20%

• NREM

  • 80 - 82%

• Sleep patterns can alter because of lifestyle changes such as:

  • retirement,

  • increased health issues including sleep disorders,

  • physical inactivity,

  • decreased social interactions,

  • increased medication use,

  • change of living arrangements and bereavement.

• A circadian phase advance occurs, and less sleep may be achieved if a person resists the body’s preference for an earlier bedtime and earlier awakening.

• Amount of N3 sleep continues to decline and may not occur at all, replaced with N2 sleep.

• there is an increase in sleep latency and multiple awakenings occur.

• Melatonin concentrations continue to decline.

• The shorter total sleep in this stage may be due to the impaired ability to obtain sleep, rather than a reduced need for sleep.

Partial Sleep Deprivation

• The experience of achieving inadequate sleep in terms of quantity or quality.

Sleep Latency

• The time taken to fall asleep

Sleep quantity

• Refers to the duration of sleep, or the number of hours you sleep.

Sleep quality

• Refers to how well you sleep, such as whether you were woken up in the night or how deep and restful your sleep is.

Partial Sleep Deprivation - Contributions

• Consuming caffeine, food, drugs or alcohol

• work or school requirements

• failing to wind down before bed

• stress

• medical conditions

• an uncomfortable sleeping environment

• social influences.

Partial Sleep Deprivation - Affective Functioning

• Refers to a person’s emotions.

• Includes:

  • Regulating or controlling emotions

  • Mood swings

  • Emotional outbursts

  • Feeling sad or depressed

  • Irritability

  • Crying for no reason

Partial Sleep Deprivation - Behavioural Functioning

• Refers to observable actions.

• Sleep deprivation:

  • may have trouble controlling your behaviour,

  • participate in more risk-taking or impulsive behaviour,

  • take longer to finish tasks,

  • have reduced productivity and work efficiency,

  • be reluctant to get out of bed in the morning

  • be more accident prone.

  • Children may show hyperactive behaviour and increased misbehaviour.

Partial Sleep Deprivation - Cognitive Functioning

• Refers to a person’s mental processing.

• When sleep deprived, you may experience these cognitive functioning issues:

  • trouble with memory

  • decreased alertness

  • poor concentration

  • impaired problem solving, decision making

  • poor judgement

  • lack of motivation

  • trouble coping with change or stress

  • difficulty learning new concepts

  • slower thinking

  • a shortened attention span.

Blood Alcohol Concentration (BAC)

• In Victoria, the legal limit for driving is under 0.05%

• levels above 0.05% have negative effects on a person's:

  • Affective (emotional) functioning

  • Cognitive (mental processing) functioning

• The negative effects increase as the levels increase

Full Sleep Deprivation (FSD)

• 17 hours of wakefulness = BAC of 0.05%

• 24 hours of wakefulness = BAC of 0.10% (above legal driving limit in Australia)

How does FSD affect driving

• Cognitive Functioning Effects:

  • Poorer concentration

  • Poorer attention,

  • Poorer decision making

  • Poorer problem-solving ability

• Affective Functioning Effects:

  • poorer emotional regulation

  • increased irritability

  • emotional outbursts

Circadian Rhythm Sleep Disorders

• Characterized by persistent sleep disruption.

• Caused by misalignment between circadian rhythm and required sleep-wake schedule.

• Affected individuals struggle to sleep and wake at appropriate times.

• Impacts attending school, work, and social activities.

• Can be treated through bright light therapy

• Consists of:

  • Delayed Sleep Phase Syndrome

  • Advanced Sleep Phase Disorder

  • Shift work.

Misalignment

• Can cause:

  • excessive sleepiness

  • insomnia

  • distress

  • impaired functioning

Bright Light Therapy

Method

• Exposing a person to light for a specific time to reset the sleep-wake cycle.

Effect:

• Activates wake-inducing biological mechanisms (circadian rhythm, suprachiasmatic nucleus).

• Delays melatonin release, promoting wakefulness.

Delayed Sleep Phase Syndrome

• Characterized by a delay in sleep onset and awakening compared to desired timing.

• Delay usually by two or more hours.

• Results in falling asleep later than required.

• Necessitates waking up later to achieve adequate sleep.

• Treated by bright light therapy

Impacts of Delayed Sleep Phase Syndrome

• Becomes a disorder when unable to get recommended sleep due to early commitments

• Results in significantly less sleep, impairing proper functioning.

Factors that increase the likelihood of DSPS

• Age:

  • More common in adolescents and young adults.

• Longer Circadian Period:

  • Delayed night-time signal to the suprachiasmatic nucleus.

  • Delayed melatonin release from the pineal gland.

• Increased Sensitivity to Light:

  • Lack of light cues delays melatonin release from the pineal gland.

Advanced Sleep Phase Disorder

• Characterized by an advance in sleep onset and awakening compared to desired timing.

• Typically falls asleep two or more hours earlier than needed.

• Impact of symptoms:

  • Varies among individuals.

  • Symptoms worsen when work or social schedules conflict with natural sleep-wake cycle.

Shift Work

• Can cause a circadian rhythm sleep disorder when a person regularly works outside of normal business hours, particularly at night and the very early morning.

• Includes:

  • Consistent night shifts.

  • Rotating schedules.

• Affects professions like:

  • Healthcare

  • Hospitality

  • Factory work

  • Transport

  • Travel

• Impacts:

  • Disrupts sleep-wake schedule opposite to natural day-night cycle.

  • Causes distress and dysfunction.

  • Leads to excessive sleepiness at work and impaired sleep at home.

Consequences of shift work

• Poor performance at work.

• Interpersonal problems.

• Increased risk of accidents.

• Poor mental well-being.

• Potential development of mental disorders (e.g., depression, substance use disorders).

Physical Health Problems Linked to Prolonged Shift Work

• Gastrointestinal disorders.

• Cardiovascular disease.

• Diabetes.

• Cancer.

Shift Work Treatment

• Rotating Schedules:

  • Should ideally shift forward (morning to afternoon to evening).

  • Allows better adjustment to changing schedules.

• Bright Light Therapy

  • Useful for adjusting circadian rhythm.

  • Exposure to light before evening or night shifts.

  • Delays melatonin release, helping maintain alertness during shifts.

Sleep Hygiene

• Refers to the sleep-related behaviours and environmental conditions that are beneficial for sleep.

• Benefits:

  • Helps fall asleep faster.

  • Improves sleep quality and quantity.

How Sleep Hygiene promotes sleep

• Avoid devices and caffeine before bed.

• Follow a wind-down bedtime routine.

• Avoid 'watching the clock'.

• Minimize light and noise.

• Ensure a cool temperature.

• Use comfortable bedding.

Zeitgebers

• Environmental cues that synchronize and regulate the body’s circadian rhythm.

• Includes:

  • Light

  • Temperature

  • Eating patterns

• These cues have different abilities to shift the 24-hour sleep-wake cycle.

• Can be purposefully used to improve sleep-wake cycle and mental well-being.

Temperature as a zeitgeber

• Controlled by the suprachiasmatic nucleus on a 24-hour cycle.

• Sleep-Wake Link:

  • Body temperature decreases in the early evening.

  • Sleep onset occurs at the greatest rate of temperature decline.

  • Lowest body temperature is about 2 hours after sleep onset.

• Skin warming helps initiate sleep.

  • Behavioral evidence: Using bedding for warmth, animals curling up or using nests.

• NREM sleep promotion linked to body cooling pathways.

• Increase in melatonin coincides with a decrease in core body temperature before sleep onset.

Best temperature for sleep

• Ideal for sleep onset: 19–21°C.

• Ideal skin and bed microclimate during sleep: 31–35°C.

Benefits of using temperature

• Regulating temperature helps initiate sleep quickly.

• Maintains sleep throughout the night.

• Improves consistency of the sleep-wake cycle.

• Enhances mental well-being.

Eating and Drinking Patterns