UNIT 1 - TOPIC 3

Consciousness

the awareness of our own thoughts, feelings and perceptions (internal events) and our surroundings (external stimuli) at any given moment. It is our subjective experience of the world, our body and our mental perspective. Consciousness includes arousal and awareness.

When is consciousness lost?

When you fall into deep sleep at night

Arousal

how responsive we are to the external environment; how awake we are. It is physiologically controlled by the reticular activating system

Awareness

how we perceive and understand our experiences and environment. It is controlled by the mechanisms and interactions of the brain cortices and influenced by our level of arousal

Consciousness as a continuum

refers to the operation of a high level of consciousness/awareness through being unconscious/unaware. This includes normal consciousness to altered states of consciousness like drowsiness and light sleep. In other words, William James viewed consciousness as an ever changing series of thoughts that shift effortlessly like water flowing from a stream.

State of consciousness

Our level of awareness of internal events and external surroundings

Normal waking consciousness

the state of consciousness we experience when we are awake and aware (moderately high levels of arousal and awareness).

Altered state of consciousness

the state of consciousness that deviate from normal waking consciousness

Continuum of arousal

the operating of a high level of arousal through a low level of arousal. From coma → general anaesthesia → deep sleep → light sleep → drowsiness → awake and alert → excitement → hyperarousal

Hyperarousal

an abnormal state of increased responsiveness to stimuli. However, it does not mean a personal will respond better to stimuli. It is a key symptom of PTSD and other stress-related disorders.

Attention

relates to the internal and external information that we are actively processing, either consciously or unconsciously. It can be selected or divided.

What stimuli can attract our attention?

novel stimuli (new or unusual), changes in stimulation (e.g. volume suddenly increasing), personally meaningful (e.g. name being mentioned across a crowded room).

Selective attention

the process of focusing on one particular object in the environment for a period of time while simultaneously ignoring or filtering out the other irrelevant stimuli in the environment.

Divided attention

the capacity to attend to and perform two or more activities at the same time (multitasking). It allows us to simultaneously process different information from various sources and to successfully complete multiple tasks at the same time.

A cognitive process

a mental function related to the use of information. It can be controlled, or conscious, such as when we learn something new, like driving a car. It can also be automatic, or unconscious, where the process occurs without us being aware of it.

What do controlled processes require?

selective attention. A person must actively focus attention to successfully complete a task.

What do automatic processes enable?

for us to have divided attention. If a task requires little mental effort and attention, we can often engage in other tasks at the same time.

Circadian rhythm

a biological rhythm that occurs approximately once every 24 hours.

Sleep-wake cycle

It is a regular cycle that is an example of circadian rhythm. It is determined by an internal body clock called the suprachiasmatic nucleus (SCN).

Suprachiasmatic nucleus (SCN)

It is located in the hypothalamus and regulates sleep by signalling the pineal gland to release melatonin when environmental light is low (at night) and also to stop the release when environmental light is high. The optic nerves detect light and send a message to the SCN to send to the pineal gland to do this.

What hormone is responsible for sleepiness?

melatonin.

Melatonin

A chemical that is produced by the pineal gland. It plays a crucial role in regulating sleep.

How is the production of melatonin regulated?

by a structure in the hypothalamus (the SCN) that receives inputs from the eyes.

What does high melatonin levels in the bloodstream indicate?

That the individual will fall asleep relatively easily.

What does daylight do to melatonin levels?

It suppresses melatonin release. This means that people do not fall asleep easily in the daytime, unless they are drowsy in the middle of the afternoon.

What focuses conscious attention?

the thalamus, cortex and reticular formation.

How does the reticular formation focus conscious attention?

It extends into both the thalamus and cortex to send signals to them. It influences which information should come to our attention (it decides its importance - saliency). It also adjusts cortical activity. It regulates circadian rhythms, heart and breathing rates and motor coordination.

How does the thalamus focus conscious attention?

It focuses attention on important visual and auditory information, and relays this information to the cerebral cortex where it is interpreted. It also inhibits unnecessary background information. It plays a key role in regulating arousal and alertness.

How does the cerebral cortex focus conscious attention?

It is the outermost layer of the cerebrum. It allows us to undertake a range of tasks from simple to complex. Also to perceive our surroundings and make sense of our experiences. It includes the prefrontal cortex and parietal cortex (somatosensory and post-parietal). It helps to maintain or shift focus on something.

What hormone is responsible for alertness?

cortisol (higher levels indicate greater alertness). It is thought to play a role in initiating wakefulness.

How do psychologists study consciousness?

physiological measurements of consciousness, behavioural and cognitive measures, self-report (objective) measures.

Physiological measurements of consciousness

electroencephalography (EEG), electromyography (EMG), and electrooculography (EOG).

electroencephalography (EEG)

It detects, amplifies and records electrical activity in the brain in the form brainwaves on the outside of the skull during sleep. The patterns of the waves can help determine the stage of consciousness a person is in or when they are drowsy or alert. Different brainwave patterns are associated with different stages of consciousness.

electroography (EOG)

It detects, amplifies and records electrical activity in the muscles around the eyes during sleep. It can help determine whether a person is in rapid eye movement (REM) (dreaming) or non-rapid eye movement (NREM) (non-dreaming) sleep.

electromyography (EMG)

It detects, amplifies and records electrical activity in the other muscles of the body (movement and tension). It helps us determine whether a person is awake or asleep and also if they are in REM or NREM sleep.

Limitations of physiological measures

1. inability to identify the participant’s private/personal conscious experience

2. changes in physiological events could be due to other reasons.

Polysomnogram

a continuously moving chart that displays data collected simultaneously from EEG, EOG, EMG and other devices. This allows a researcher to compare corresponding data at once and make more informed decisions about a person’s state of consciousness and any underlying problems.

Sleep

A naturally occurring altered state of consciousness marked by a diminished sense of awareness and responsiveness to the external environment. It follows a predictable sequence of stages.

How long is a sleep cycle

90 to 120 minutes

Types of sleep

1. Non-rapid eye movement (NREM)

2. Rapid eye movement (REM)

How many stages does NREM have and how are they predominantly measured?

3 stages, lasting about 80 percent of our total sleep. There used to be a 4th stage, however it is now part of the 3rd stage. It is predominantly measured through brainwave patterns.

NREM sleep

Characterised by a progressive reduction in physiological activity. It is thought that our body repairs itself during NREM sleep.

How is Stage 1 NREM sleep entered?

We enter a relaxed state known as a hypnogogic state. We can experience hallucinations like flashing lights and vivid images. Also hypnic jerks are common.

Stage 1 NREM (N1) sleep

Sometimes called the pre-sleep stage because it is very light sleep that drifts in and out from which people are easily awakened. It can last between 30 seconds to 10 minutes. It begins to reduce body temperature, brain activity and heart rate. If we are woken, we wouldn’t believe we were asleep.

Stage 2 NREM (N2) sleep

Light sleep, but deeper than N1 sleep. People spend most time in this stage. It can last between 10 to 25 minutes per sleep cycle. Humans spend most of their sleep at this stage. If we are woken, we wouldn’t believe we were asleep.

Stage 3 NREM (N3) sleep

Referred to as the “slow-wave sleep” due to reduced brain activity. It is the deepest sleeping stage. It typically lasts between 20 to 40 minutes per sleep cycle. It is extremely difficult to wake someone in this sleep stage.

REM sleep

Lighter than N3 sleep and characterised by rapid eye movements, increased brain activity and vivid dreaming. The first cycle of REM sleep lasts for about 10 minutes. If we were woken in this stage, we would likely report that we were dreaming.

What physiological activity happens during REM sleep?

increases and fluctuations in heart rate, blood pressure and respiration. Body temperature tends to match the surrounding environment and there is no muscle tension.

What is REM often referred to and why?

Paradoxical sleep because the exterior body appears calm but the interior is just as highly active as it would be when awake.

What physiological changes determine stages of sleep?

brainwave patterns, muscle tension, eye movement, body temperature, heart rate, blood pressure, respiration and hormone release.

How does REM and NREM progress throughout the FIRST cycle?

REM → N1 → N2 → N3 → N2 → REM. It lasts around 90 minutes.

Which type of sleep does dreaming usually occur?

REM sleep which lasts around 2 hours. For light sleepers or anxious people, dreaming can be experienced in NREM sleep.

Summary of physiological characteristics of each sleep stage

Evolutionary theories

It focuses on when and why different species sleep, with regards to increasing survival. Some propose that sleep contributes to increasing our chances of survival. This is because each species have adapted their sleep patterns to their environmental conditions over time and their chances of survival have increased.

What hypotheses does the evolutionary theory have?

1. Animals sleep based on their vulnerability to predators. It keeps them hidden by unseen predators and restores their strength to fend them off e.g. mice sleep more to hide from carnivores.

2. Sleep depends on the need to find food e.g. cows need to graze grass more for hours and sleep less.

3. Sleep conserves energy e.g. hibernating bears when food is scarce.

4. It helps with cognitive functions such as memory consolidation and learning.

Criticisms for evolutionary theory

1. Assumes that sleep is useful but not essential.

2. It doesn’t take into account the different sleep patterns different animals may have.

3. Assumes sleep is a way to hide safely from predators.

4. Although the theory states that sleep helps with survival through adaptive functions, it is argued that this is a correlation - not a direct cause-and-effect relationship because there are other benefits to sleep that is not survival.

Restoration theories

It focuses on why sleep is important for recharging, growing and recovering from physical and psychological work during the day.

What hypotheses does the restoration theory have?

Sleep allows us to:

1. Recharge our bodies (grow and recover).

2. Replenish the body and prepare it for the next day. Sleep looks after the health of the physical body.

3. Sleep rids us of adenosine which is a neurotransmitter produced when our cells use energy and is a cellular waste product that accumulates when we are awake.

4. Sleep increases alertness and assists our psychological state. When sleep is inadequate our norepinephrine (a neurotransmitter) is affected and this keeps us alert.

5. Sleep enhances mood. Hormones and neurotransmitters that affect mood and and emotions are activated during sleep.

6. Animals with higher metabolic rates are likely to spend more time sleeping to assist in recovery

7. Sleep activates growth hormone which in turn controls metabolism.

8. Sleep increases immunity to disease

Criticisms for restoration theory

1. No evidence shows that inactivity reduces sleep patterns compared to active people.

2. Amount of sleep varies between everyone (people can functoin even with little sleep) - so lots of sleep is not always needed. This theory struggles to explain why.

3. Some research suggests that short naps can still boost alertness and brain function, not just one long period of sleep.

4. Sleep actually does not have a cause-and-effect relationship with restoration. The theory demonstrates associations with research, rather than definitive evidence of causation.

5. There is little evidence that we need more sleep after exercise - we do tend to sleep longer but only by 10 minutes.

6. Assumes that the brain rests during sleep. However, it is active to assist the body with getting ready for the next day.

Delayed sleep-wake phase disorder

a circadian phase disorder that delays sleep patterns, often seen in adolescents.

Sleep-wake hormones

melatonin and cortisol

How many hours of sleep do newborns have?

about 16 hours

How many hours of sleep does childhood have?

about 10 to 12 hours

How many hours of sleep do adolescents have?

about 9 to 10 hours

How many hours of sleep do early-middle adults have?

about 7 to 8 hours

How does REM and NREM progresses throughout the night?

The amount of time spent in REM sleep increases and NREM sleep decreases as the night progresses. This means that before we wake up, we are in REM sleep.

How does REM and NREM progress throughout the SECOND cycle?

N2 → N3 → N2 → REM

How does REM and NREM progress throughout the THIRD cycle?

excludes N3, includes a longer N2, and extends time spent in REM.

How does REM and NREM progress throughout the FOURTH TO SIXTH cycle?

rarely includes N3 and continues to show increased time in REM. We also tend to wake up briefly (usually without conscious awareness) and roll over before going back to sleep either before/after a period of REM sleep or directly after N2.

Typical hypnogram of one night’s sleep

Adolescent sleep-wake shift

a biological shift in the circadian rhythm

What does the adolescent sleep-wake shift do?

It causes teenagers to feel sleepy later at night and to wake up later in the morning.

Why does the adolescent sleep-wake shift occur?

The release of sleep–wake hormones like melatonin (which induces sleepiness) and cortisol (which promotes alertness) is delayed by about two hours in adolescents. As a result, they tend to fall asleep around 11 pm instead of the typical adult bedtime of 9

What does the adolescent sleep-wake shift cause?

Emotional stress, low daytime alertness, mood disturbances, and increased risk of depression and insomnia.

What are other reasons that can cause the adolescent sleep-wake shift

Busy schedules and stimulation from technology, schoolwork, part-time jobs, and social activities, leading to sleep deprivation. A sleep and wake schedule of 11 pm–7 am (typical during school days) creates a sleep debt of at least five hours per week, which can become chronic.

What is advanced sleep-wake phase disorder?

It is prevalent in older adults and it is when they feel sleepy earlier in the evening (around 6–9 pm) and wake very early in the morning (2–5 am). This also affects their ability to fall back asleep, causing interrupted or shorter sleep.

Why can delaying school times be beneficial for adolescents?

Studies have shown that it can help adolescents align better with their natural body clock, resulting in more sleep, improved focus, better grades, and fewer absences.

What factors affects how much sleep a person needs?

age, lifestyle and genetics

Sleep deprivation

when our sleep needs are not met

Types of sleep deprivation

partial, chronic and total

Partial sleep deprivation

experienced when a person does not get the full amount of sleep they need (poor quantity sleep) or when a person is deprived of one particular stage of sleep (poor quality sleep). It has affective (mood), behavioural and cognitive (concentration) effects, as well as physiological effects.

Partial sleep deprivation effects

Affective include mood disturbances like amplified emotional responses, confusion and irritability, feelings of sadness. Behaviour include problems performing tasks, clumsiness, risk-taking behaviour, slowed performance. Cognitive include impaired creativity, memory problems, poor decision-making. Physical include droopy eyelids, headaches, slower physical reflexes.

Chronic sleep deprivation

occurs when partial sleep deprivation is ongoing over an extended period of time.

Total sleep deprivation

when a person has no sleep in a 24-hour or longer period. Tasks requiring concentration (sustained attention) are seriously impaired. Mood can be irritable and confused.

Sleep deprivation psychosis

occurs when total sleep deprivation is ongoing over an extended period of time. It can increase difficulty in coping with others and the environment.

What stages of sleep are crucial for optimal functioning?

REM and Stage 3 NREM. REM is suggested to be more psychological well-being while Stage 3 NREM is for physiological well-being. But, some psychologists suggest otherwise.

Lack of REM sleep and the link with mood disturbances

REM sleep pauses the release of certain neurotransmitters like norepinephrine, which helps brain receptors recover and become more responsive, meaning they react better when the chemical is released again. If these chemicals don’t get their break, it can affect mood and learning like causing irritability, sadness, or grumpiness.

The effects of loss of NREM sleep

During NREM sleep, the body repairs itself and restores its tissues. One way it does this is by releasing growth hormones. If a person doesn’t get enough NREM sleep, especially stage 3, this repair process might not happen properly.

Circadian phase disorder

a sleep disorder in which a person’s circadian rhythms are disrupted e.g. adolescents’ delayed sleep-wake phase shift.

Two key factors that can disrupt our circadian rhythms and lead to a circadian phase disorder

shift work and jet lag

Sleep disorders

shifts in our sleep-wake cycle

Common sleep disorders

narcolepsy, sleep-onset insomnia, sleep apnoea, and sleepwalking

What effects does sleep disorders have?

sleep deprivation, which can impact school, work, relationships, social problems, health issues and safety.

Narcolepsy

a debilitating sleep disorder that causes sudden sleep attacks during the day. It does not matter how long the person has slept the night before, the sleep attacks still occur. Narcolepsy is thought to affect males and females equally.

Effects/symptoms of narcolepsy

• Sleepiness during the daytime

• Loss of muscle control

• REM hallucinations

• Can experience cataplexy

• Beginning nighttime sleep with REM

Causes of narcolepsy

• Can run in families

• Highly emotional events

• Could be triggered by medications or illnesses

Prevalence of narcolepsy

relatively rare compared to other sleep disorders, men and female is equally affected

Treatments for narcolepsy

• Maintaining a routine sleep schedule

• Regular exercise

• Healthy diet

• Scheduling naps during the day

• Avoiding alcohol and caffeine

Sleep-onset insomnia

trouble falling asleep at the beginning of the night (takes 30 minutes or more).

Effects/symptoms of sleep-onset insomnia

• Inability or excessive time to fall asleep at the start of the night

• Unsatisfactory sleep

• Excessive daytime sleepiness

• Fatigue

• Low energy

• Moodiness