How Does Sleep Affect Mental Processes and Behaviour

What is consciousness?

The level of awareness an individual has of their thoughts, feelings, perceptions, and existence.

What is a psychological construct?

An agreed upon description and understanding of psychological phenomena that cannot be overtly measured or observed.

What is normal waking consciousness (NWC)?

Is a state of consciousness in which an individual is awake and aware.

What is altered state of consciousness (ASC)?

A state of consciousness that is distinctly different from normal waking consciousness in terms of quality of experience and levels of awareness.

What is naturally occurring consciousness?

A type of altered state of consciousness that occurs without intervention.

What is induced consciousness?

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

What is sleep consciousness?

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

What is REM (rapid-eye movement) sleep?

Type of sleep characterised by rapid eye movement.

What is NREM (non-rapid eye movement) sleep?

Type of sleep characterised by a lack of raid eye movement and is subdivided in three stages.

What is a sleep episode?

A full duration of time spent asleep.

What is a sleep cycle?

An approximately 90-minute period that repeats during a sleep episode in which an individual progresses through stages of REM and NREM sleep.

What are the characteristics of REM sleep?

-The sleeper is considered to have a highly active brain and a less active body during REM sleep.

-The sleeper is virtually paralysed during REM sleep, meaning that most muscle movement is not possible.

-Vivid dreaming tends to occur during REM sleep.

-REM sleep makes up approximately 20-25% of a sleep episode for most age groups.

What are the characteristics of NREM sleep?

-The sleeper is considered to have a less active brain than normal waking consciousness.

-Physical movement is possible in NREM sleep.

-Dreams can occur in NREM sleep but they are often non-vivid.

-NREM sleep makes up approximately 74-80% of a sleep episode.

What happens NREM stage 1?

-When moving into stage 1 of NREM sleep, the sleeper transitions from being awake into a light sleep.

-This transition is signified by the experience of the hypnagogic state, in which some people experience feelings of floating, falling or a sudden jerk.

What happens NREM stage 2?

-The sleeper is still in a relatively light sleep.

-The sleeper is considered truly asleep.

What happens NREM stage 3?

The sleeper is in a deep stage of sleep.

What is electroencephalography (EEG)?

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

-EEG will show a higher frequency and lower amplitude when in normal waking consciousness, and a lower frequency and higher amplitude during an altered state of consciousness.

Therefore, an EEG is likely to show:

-Higher frequency and lower amplitude in REM sleep.

-Higher frequency and low amplitude in NREM sleep stage 1.

-Medium frequency and medium amplitude in NREM sleep stage 2.

-Lower frequency and higher amplitude in NREM sleep stage 3.

(Frequency is the number of brain waves that occur per second, whilst amplitude is the intensity and height of the brain waves.)

What is electromyography (EMG)?

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

-During REM sleep, EMG readings show low activity.

-During NREM sleep, EMG readings show medium/moderate activity.

What is electrooculography (EOG)?

-A device that detects, amplifies, and records the electrical activity of the muscles responsible for eye movement.

-During REM sleep, an individual experiences rapid eye movement, so an EOG is likely to show high activity.

-During NREM sleep, an individual does not experience rapid eye movement, so an EOG is likely to show low activity.

What is a sleep diary?

A record containing self-reported descriptions from an individual about their sleeping periods, including an estimated time spent sleeping and judgements they might have about the quality and nature of their sleep.

-This method is subjective and therefore can be less reliable than objective measures such as EEGs, as individuals may not be able to determine the exact time they fell asleep for be able to remember the quality of their sleep upon waking.

What is video monitoring?

Involves the use of camera of audio technologies to record an individual as they sleep.

What is a circadian rhythm?

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

What is the sleep wake cycle?

24 hour cycle that is made up of time spent sleeping and time being aware and alert.

-This is a type of circadian rhythm.

What are ultradian rhythms?

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

What are sleep cycles?

One sleep cycle lasts about 90 minutes (factors such as age, health, the environment, etc).

What is the suprachiasmatic nucleus (SCN)?

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

-Plays a role in regulating our sleep-wake cycle by acting like an internal body clock.

-External cues involve information from the environment, such as the presence or absence of light.

-Internal cues involve information that originates within the body.

-The information from our internal cues and external cues dictate the messages that the SCN sends to the pineal gland, which is a gland in the brain responsible for the production and release of melatonin.

What is melatonin?

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

-Does not directly induce sleep but rather promotes a state of calm and relaxation to help make it easier to fall asleep.

-Melatonin peaks between 2 and 4 am, when individuals are typically in the deepest sleep, before gradually declining over the night and before waking in the morning.

-Melatonin levels are at their highest at the night-time and lowest in the morning.

-The level of melatonin in the body helps to regulate the sleep-wake cycle.

What is the neonatal period (1-15 days)?

-Sleep duration is the highest.

-Approximately 16 hours of sleep.

-Approximately 50% of the sleep episode is REM sleep and approximately 50% is NREM sleep.

What is infancy (3-24 months)?

-Approximately 13.5 hours.

-Proportion of NREM sleep increases slightly to around 80%.

-REM sleep decreases approximately to 20%.

What is childhood (2-14 years)?

-Approximately 11 hours.

-Proportion of NREM sleep increases slightly to around 80%.

-REM sleep decreases approximately to 20%.

What is adolescence (14-18 years)?

-Approximately 9 hours.

-20% REM and 80% NREM.

What is young adulthood (18-30 years)?

-Approximately 7.75 hours.

-20% REM and 80% NREM sleep.

What is middle adulthood (30-75 years)?

-Approximately 7-8 hours.

-20% REM and 80% NREM.

What is old age (75+)?

-Approximately 6 hours.

-20% REM and 80% NREM.

What is neonatal period and infancy?

REM sleep is significantly high due to experiencing rapid brain development.

What is adolescence?

More prone to delayed circadian phase disorders in which their biological clocks are not in alignment with the demands of their environments.

What is adulthood and old age?

Lower levels of sleep tend to be attributed to ill-health and an increase in the prevalence of sleep disorders.

What is sleep deprivation?

Inadequate quantity and/or quality of sleep.

What is full sleep deprivation?

When an individual has no sleep within a 24 hour period.

What is partial sleep deprivation?

When an individual sleeps for some duration within a 24 hour period, but the sleep duration is too short, or the quality of sleep is poor.

What are the affective effects of sleep deprivation?

Changes in emotions and emotional responses that arise from sleep deprivation.

“Affect” is a term used to describe the experience, regulation and expression of emotions.

What do the affective effects of sleep deprivation include?

-Poor emotional regulation.

-Reduced ability to cope with stress.

-Increase in aggression and impatience.

What are the behavioural effects of sleep deprivation?

Changes in actions and the ability to control them that arise from sleep deprivation.

What do the behavioural effects of sleep deprivation include?

-Increased likelihood of engaging in risk-taking behaviours.

-Reduced efficiency.

-Diminished social functioning and impaired control of behaviour.

What are the cognitive effects of sleep deprivation?

Mental processes an individual performs in order to understand and process information.

What do the cognitive effects of sleep deprivation include?

-Reduced concentration.

-Impairment of short-term memory.

-Lapses in attention.

-Impaired visual and spatial ability.

What is Blood alcohol concentration (BAC)?

-A measure of how much alcohol is in a person’s bloodstream.

-It will slow down the nervous system and decreased alertness, concentration, reflexes and decision-making.

-A BAC of 0.05 is roughly equivalent to 17 hours of sleep deprivation (partial sleep deprivation).

-A BAC of 0.10 is roughly equivalent to 24 hours of sleep deprivation (full sleep deprivation).

What are sleep disorders?

Disturbances to typical sleeping and waking patterns.

What are circadian rhythm sleep disorders?

Sleep disorders interfere with the typical regulation of the circadian rhythm of sleep, leading to a change in the sleep-wake cycle.

What are the causes of circadian rhythm sleep disorders?

Circadian rhythm sleep disorders are fundamentally caused disruption to the sleep-wake cycle.

What are the effects of circadian rhythm sleep disorders?

Experiencing some form of sleep deprivation.

What is delayed sleep phase syndrome (DSPS)?

A type of circadian rhythm sleep disorder in which sleep and waking occur later than usual.

-Caused by a misalignment between external and internal cues that regulate the circadian rhythm.

What is advanced sleep phase disorder (ASPD)?

A type of circadian rhythm sleep disorder in which sleep and waking occur earlier than usual.

-ASPD is caused by a misalignment between external and internal cues that regulate the circadian rhythm.

-Melatonin secretion occurs later for individuals with DSPS and earlier for individuals with ASPD.

What is shift work?

-An occupation that involves working at unusual hours, such as working overnight.

-Shift work is considered to be a cause of sleep problems.

What is bright light therapy?

A method used to adjust a person’s circadian rhythm through exposure to a high-intensity light source.

What is sleep hygiene?

A term used to describe the practices and habits that promote an individual’s sleep patterns.

What does sleep hygiene involve?

Time, sound, light, comfort, technology/devices, association with bed, food and drink consumption, exercise.

What is mental wellbeing?

-An individual’s psychological state, involving their ability to think, process information and regulate emotions.

-Good sleep is likely to reduce the likelihood of mental problems and promote mental wellbeing.

-The relationship between sleep and mental wellbeing is bidirectional, meaning that sleep can impact mental health and vice versa.

What are zeitgebers?

-External cues from the environment that influence the circadian rhythm.

-Signals that regulate the circadian rhythm, and they consequently help to promote sleepiness and wakefulness at appropriate times.

What is bluelight?

A type of light that can be emitted both naturally and artificially.

What is daylight?

The typical light an individual is exposed to during the day and is mostly natural blue light.

-Regulates the sleep wake cycle by signalling to the SCN to cease melatonin production and promote wakefulness.

What is artificial blue light?

Can also act a an external cue to do the same.

What is temperature?

The degree of external heat in the environment that can influence the quality and quantity of sleep.

-Research contends that 18.3 celsius is an ideal room temperature for sleep.

What are eating and drinking patterns?

What, when and how much food and drink is consumed by an individual.