PSYCH NOTES UNIT 4 AOS 1: demand and importance of sleep

Sleep

Regular, naturally occurring altered state of consciousness that involves a loss of awareness and disengagement with internal and external stimuli. Made up of multiple cycles of Rapid Eye Movement (REM) and Non- Rapid Eye Movement (NREM) (known as Sleep Cycles).

Experience of sleep is subjective, characterised by: 

·       Reduced ability to control behaviour 

·       Less accurate understanding of the passage of time

·       Perceptual and cognitive distortions 

·       Rapid Eye Movement 

·       High level of brain activity 

·       Low levels of physical activity 

Sleep cycle is approx. 90 minutes that repeats progressing through REM & NREM.

Suggest two reasons why sleep is categorised as an altered state of consciousness (2 marks)

Sleep is considered an altered state of consciousness as:

• those who are asleep are not aware of the passage of time passing

• or aware of their environment around them, 

which those in a normal waking consciousness are.

Divided into 3 stages of NREM sleep:

·       NREM stage 1: Awake to light sleep. Experience of hypnagogic state- feeling of floating, falling or sudden jerk. Loses awareness of self but aware of faint sounds in environment. Sleeper easily woken in this stage.

·       NREM stage 2: relatively light sleep. Spend majority of time in this stage. Considered ‘truly’ asleep.

·       NREM stage 3: deep stage of sleep. Difficult to wake sleeper. Woken in this stage = feelings of drowsy & disorientated. Sleepwalking & sleep talking most likely to occur.

Ways to measure sleep:

Electroencephalograph (EEG), Electromyograph (EMG), Electro-oculography (EOG), Sleep Diaries, Video Monitoring.

Sleep measures can be disruptive & invasive and therefore may not provide a true reflection of individuals sleep patterns.

The “Graphs”: EEG, EOG & EMG’s considered to be

objective measures. Provide reliable, unbiased quantitative data. Do not provide qualitative detail.

Sleep diaries are

subjective measures: Accuracy & reliability may be limited.  

Video monitoring is an

objective measure: it’s interpretation can be subjective, just like the interpretation of the graphs.

Brain Waves (patterns):

correlate to different states of consciousness. Vary in frequency (rate) and amplitude (height). Frequency & Amplitude indicate what state of consciousness an individual is experiencing. EEG show higher frequency & lower amplitude when in NWC and lower frequency & higher amplitude during an ASC.

Strength	Weakness
·       Useful for sleep studies. ·       Diagnosis of patients with brain damage/neurological or mental disorder	·       Neural activity under thick skull. ·       Not entirely precise  ·       Does not pinpoint functional/dysfunctional areas of brain

Electroencephalography (EEG):

device that detects, amplifies and records electrical activity of the brain. Neurons communication is shown through electrical impulses (detected by EEG as brain waves). To take readings, researcher attached electrodes to the outside of a person's head. 

Electromyography (EMG):

Detects, amplifies and records electrical activity in muscles of the body. Electrodes attached to skin above muscles. Muscle movement can be used to identify different stages/types of sleep through how active a person's muscles are. 

Electro-oculography:

Detects, amplifies and records electrical activity in muscles responsible for eye movement. Electrodes are attached to the skin above the muscles. Eye movements are a physiological response that can be used to investigate the sleep that is being experienced. REM & NREM is distinguished by eye movement. 

Biological Rhythms:

Repeated biological processes that are regulated by internal mechanisms. 2 types of biological rhythms:

Circadian Rhythms: Sleep wake Cycle:

biological and behavioural changes that occur as a part of a cycle, last around 24 hours. Sleep-Wake Cycle (24-hour cycle of time spent sleeping & time spent awake/active). The daily human sleep, wake cycle is the most extensively studied circadian rhythm, happens due to both internal and external factors.

Ultradian Rhythms: Sleep cycles of REM & NREM sleep.

·       Biological and behavioural changes that occur in a cycle that lasts less than 24 hours. Some biological processes as example are rhythm include heart rate, digestion, blood pressure, some hormone secretions, appetite and a sleep episode. 

Sleep episode:

full duration of time spent asleep from falling asleep to waking. Repeated, approx. 90-minute period of where it progresses through REM & NREM stages. Sleep cycle is example of a ultradian rhythms due to repeat in physiological activity.

Suprachiasmatic Nucleus: 

Area of the Hypothalamus, responsible for regulating an individual's sleep-wake pattern, by playing a key role in regulating sleep-wake cycle (internal body clock). At specific times in a 24-hour day, the suprachiasmatic nucleus sends signals to regulate various activities in the body and keep it functioning to a daily schedule of sleep and wakefulness. The SCN is made up of 2 nuclei, approximately 10,000 neurons each (located above the optic chiasm). 

Suprachiasmatic Nucleus as the internal clock

The suprachiasmatic nucleus can function independently to maintain an approximately 24-hour cycle because of a precise feedback loop of gene expression and inhibition. However, it is influenced by info from both external and internal cues:

·       External cues (zeitgebers) = presence or absence of light, exercise, social activity, eating patterns and temperature.

·       Internal cues= information that originates within the body i.e. suppression of genes.

Suprachiasmatic Nucleus & Hormones:

Internal/External cues dictate messages that SCN sends to pineal gland in brain.  

-       Pineal gland: responsible for the release of melatonin. 

-       Melatonin: hormone released to induce sleep as a part of the sleep wake cycle. Levels around 8-9pm start to induce calmness which aims to promote sleepiness. Usually leading for someone wanting to sleep around 10/11pm and peaks between 2-4am. Does not directly induce sleep but promotes a state of calm and relaxation.

-       Cortisol: responsible for increasing alertness and maintaining heightened arousal, produced by the adrenal gland, not the SCN.

Suprachiasmatic Nucleus & 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.

-       At night-time when the eyes detect no light, suprachiasmatic nucleus sends a signal to pineal gland, resulting in the pineal gland releasing melatonin. This induces sleepiness and decreases cell activity. This process ensures that our sleep is connected to night-time.

-       During the 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. Less melatonin release by the pineal gland increases cell activity in the body, resulting in wakefulness during the day. This process regulates when you go to sleep and wake up, but a different process regulates how much you sleep.

With light cues from the Sun reliably cycling every 24 hours, circadian rhythm can undergo daily resetting that keeps a person’s sleep (wake cycle aligned to a 24-hour day). However, if these light cues are absent, circadian rhythm tends to run free and can cycle for a little longer than 24 hours, resetting on average every 24.25 hours. Variations in circadian rhythm may explain some of the individual differences in those who are a ‘morning lark’ and feel more wakeful in the morning, or those who are a ‘night owl’ and feel more wakeful in the evening.

Sleep across the lifespan:

Sleep requirements change because of the change in physical and cognitive needs throughout lifespan. 

REM- important for cognitive development

NREM- important for physiological rest 

Characteristics of Sleep: Neonatal: 1-15 days old:

Newborns do not have an established circadian rhythm, so sleeping patterns are erratic, with their sleep distributed across the full 24-hour day. Sleep duration is the highest it will ever be. (approx. 16 hours). 50/50% of each sleep episode is REM/NREM sleep.

Characteristics of Sleep: Infancy: 3-24 months of age:

From about 4 months, an infant’s sleep becomes more nocturnal. As they continue to develop and experience rapid physiological changes, children begin to have a consistent circadian rhythm. Sleep duration decreases to approximately 13.5 hours. Proportion of REM & NREM sleep in sleep episode changes to 35% & 65% respectively.

Characteristics of Sleep: Childhood: 2- 14 years:

Sleep period decreases again to approximately 11 hours. NREM sleep period increases to 80% per sleep episodes. Variations of the amount of REM & NREM as this age period is quite expansive.

Characteristics of Sleep: Adolescence: 14-18:

Experience a shift in their circadian rhythm - a biological delayed sleep onset; they may not feel tired until later in the evening and wake later. This can result in a delayed sleep phase syndrome. Sleep period duration decreases to approximately 9 hours. REM & NREM periods remain consistent in each sleep episode - approximately 20% & 80% respectively.

Characteristics of Sleep: Young Adulthood & Middle Adulthood: 18-30 (young adulthood) & 30-75 (middle adulthood):

Circadian rhythm returns to more normal timing, and most healthy adults experience a consistent circadian rhythm if they are following a regular routine with relatively stable bedtimes and wake times. Sleep period duration decreases to 7.75 hours. REM & NREM sleep consistent from adolescence.

Characteristics of Sleep: Old Age: 75+:

Older adults may prefer an earlier bedtime and therefore an earlier waking in the morning and may experience advanced sleep phase syndrome: a biological shift forward in sleep-wake cycle. Duration of sleep decreases to approx. 6 hours. REM & NREM still consistent from previous age groups.

Differences across the lifespan. 

Sleep Deprivation can be understood in 2 categories: 

·       Full Sleep Deprivation: no sleep within a 24-hour period. 

·       Partial Sleep Deprivation: has sleep for some duration within a 24 hour period, but duration is too short or has poor quality of sleep.

Both have negative effects on individuals functioning ability.

Based on the individuals’ needs as some may require greater duration of sleep to feel fully rested.  If a person has not slept for time required for their age/quality is lacking, they may feel partially sleep deprived.

Effects of Sleep Deprivation

Adverse effects on emotions, behaviours and ability to think clearly, these are described as: 

Affective (Experience, regulation and expression of emotions) effects: changes in emotions and emotional responses. 

·       Poor emotion regulation. 

·       Irritability & moodiness 

·       Reduced ability to cope with stress 

·       Reduced empathy 

·       Impaired ability to appropriately
respond to situations. 

·       Increase in aggression 

·       Increase in mood swings.

Behavioural effects:
changes in actions and ability to control them that arise.

·       Sleep inertia 

·       Excessive sleepiness during the day 

·       Increased likelihood of risk-taking
behaviour 

·       Fatigue/lack of energy 

·       Slowed reactions 

·       Reduced efficiency 

·       Reduced motor control 

·       Involuntary lapses into microsleep

Cognitive (mental process in individual performance) effects: changes in mental process from sleep deprivation. 

·       Reduced concentration 

·       Impairment of STM 

·       Diminished ability to perform
cognitive tasks 

·      Lapses in attention 

·      Impaired decision-making
& problem solving
- Reduced retention of
information  
- Irrational/illogical
thinking 
- Impaired visual and
spatial ability

Delayed Sleep Phase Syndrome (DSPS):

Sleep rhythm disorder where sleep and waking occur later than usual. Misalignment between internal and external cues (specifically external cues are received at an appropriate time but internal cues are not). Causing melatonin secretion to occur later and therefore sleep wake time occur later. Must experience for at least 3 months for official diagnosis. Other than age, some predisposing risk factors for DSPS include a longer than average circadian period and an increased sensitivity to light.

Advanced Sleep Phase Syndrome (ASPD):

A sleep rhythm disorder where sleep and waking occur earlier than usual.  Misalignment between internal and external cues (specifically external cues are received at an appropriate time but internal cues are not). Causing melatonin secretion to occur earlier and therefore sleep wake time occur earlier. A person’s adverse exposure to light can maintain their undesired advanced circadian rhythm. By going to bed early and then waking early, a person is not exposed to the regular evening low light and morning bright light signals, which then perpetuates the advanced circadian rhythm cycle, maintaining the disorder.

Shift Work:

Impact on the circadian rhythm as they are continuously adapting their sleep to the environment. 

Shift work is a cause of sleep problems, rather than a sleep disorder. 

·      Insomnia 

·      Fragmented sleep 

·      Circadian rhythm phase
disorder 

·      Quality/Quantity of
sleep.  

Caused by problems with external Cues.

The consequences for a circadian rhythm sleep disorder caused by shift work include poor performance at work, interpersonal problems, increased risk of accidents and poor mental wellbeing, which can even lead to other mental disorders such as depression and substance use disorders. Research has consistently found a link between prolonged shift work and physical health problems such as gastrointestinal disorders, cardiovascular disease, diabetes and cancer.

Bright Light Therapy as treatment (BLT):

is a method used to adjust an individual’s circadian rhythm through exposure to high-intensity light source. Works to readjust the circadian rhythm.

Session last from 15 minutes to a couple of hours, conducted a few times a day. Minor improvements are seen in first few days, significant results are seen over a few weeks.   

how can bright light therapy be used as a treatment?

Improving sleep: Sleep hygiene: 

Practices and habits that promote individuals sleep patterns, beneficial as it improves sleep quality and quantity. Sleep hygiene improves all sleep wake patterns.

involves:

 ·       Time 

·      Sound 

·      Light 

·      Comfort 

·      Technology 

·      Associations with bed

·      Exercise 

Sleep hygiene & Mental Wellbeing:  

Research suggests that there is a link between poor sleep and mental illness. Good sleep will therefore reduce the likelihood of mental health problems and promote mental wellbeing. 

Sleep and Mental wellbeing= bidirectional relationship. 

Zeitgebers- Daylight & Blue Light: 

Daylight is the typical light an individual is exposed to during the day - The ability of the circadian system to resynchronise daily to keep in sync with the external environment is an evolutionary benefit. However, since the invention of artificial lighting, our light exposure is no longer just from the Sun during daylight hours, and this can be at the expense of our wellbeing. Blue light is a type of light that can be emitted both naturally and artificially -  is a range of the visible light spectrum that is emitted from smartphone screens, computer monitors, televisions, LED and fluorescent light bulbs, as well as the Sun.

Zeitgebers- Temperature:

The degree of external heat in the environment that can influence both quality and quantity of sleep. Body temperature is a biological mechanism regulated on a 24-hour circadian rhythm, controlled by the suprachiasmatic nucleus. Body temperature begins to decrease in the early evening, with sleep onset occurring when core body temperature is at its greatest rate of decline. An increase in blood flow to the skin results in skin warming and so heat is lost from the body and body temperature drops. The lowest body temperature occurs at about 2 hours after sleep onset. Suggested link between a cool room temp and experiencing improved quality and quantity of sleep - Research has determined that the ideal room temperature for sleep onset is 19–21°C BUT the ideal skin and bed microclimate is 31–35°C during sleep. This means that the combination of a cool room and warm bedding is an easy way that most people can promote sleep. These strategies may be of particular use to the elderly age group because they typically have more trouble with normal thermoregulation. Research suggests that extreme temperatures (very high or very low) are not good for sleep quality and quantity.

Zeitgebers- Eating & Drinking Patterns:

Refers to when, what and how much food/drink is consumed. Can impact the quality and quantity of our sleep - The suprachiasmatic nucleus is not largely influenced by the timing of meals, provided enough food is ingested. However, the suprachiasmatic nucleus is affected by long-term severe food deprivation, calorie restriction and perceived starvation.

	Impact on sleep
What we eat/drink	Some foods can negatively impact sleep & some can positively impact sleep  ·       Caffeine (shows effects on sleep quality even when consumed up to 6hrs before sleep onset!) ·       Alcohol ·       Spicy foods ·       High sugar/high fats
When we eat/drink	Eating closer to sleep can make it harder to  fall asleep due to stimulation of digestive system - eating meals within 3–4hrs of the onset of sleep can negatively affect sleep quality, increase sleep onset time and increase awakenings.
How much we eat/drink	Going to sleep hungry can lead to poorer sleep quality/quantity additionally, going to sleep overly full can impair sleep patterns