sleep

8A

Partial Sleep Deprivation

Inadequate sleep in terms of quantity or quality.
Sleep quantity refers to the duration of sleep.
Sleep quality refers to the quality of sleep.
Factors contributing to sleep deprivation include:
Consumption of caffeine, food, drugs, alcohol.
Work or school requirements.
Failure to wind down before bed.
Stress.
Medical conditions.
An uncomfortable sleeping environment.
Social influences.

Negative Effects =

Negatively impacts affective, behavioural, and cognitive functioning.
Poor concentration leads to increased clumsiness, causing frustration.

Affective functioning

a person’s experience of their emotions
Emotions experience can be influenced by sleep deprivation.
Symptoms include mood swings, emotional outbursts, sadness, depression, irritability, and crying.
Over-annoyed responses to household chores may occur.

Behavioural functioning

a person’s observable actions
Sleep deprivation can lead to difficulty controlling behaviour, increased risk-taking, and impulsiveness.
It can also reduce productivity and work efficiency.
Children may exhibit hyperactive behaviour and increased misbehaviour.
Sleep deprivation can cause difficulties following class rules and 'naughty' behaviour.

Cognitive functioning

a person’s mental processing

Sleep Deprivation and 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.
Example: Difficulty concentrating and remembering theory during Maths tests.

(BAC)

Blood alcohol concentration
the percentage of alcohol in the bloodstream
Alcohol has harmful effects on the brain and body, leading to laws limiting blood alcohol concentration (BAC) for driving. In Victoria, the legal BAC is under 0.05%.
A BAC level above this limit negatively affects affective and cognitive functioning, increasing as BAC increases. A study found that 17 hours of sustained wakefulness equivalent to a BAC of 0.05% or 0.10%, respectively.

Study Highlights Driving Dangers

• Importance of community understanding of sleep-deprived driving.

• Similar effects to intoxicated driving.

• Longer wakefulness over 17 hours is concerning.

• Effects of sleep deprivation are worse than legal BAC limit in Australia.

Sleep deprivation can lead to cognitive functioning issues such as:

memory problems
decreased alertness
poor concentration
impaired problem-solving
poor judgement
lack of motivation
coping with change
difficulty learning new concepts
slower thinking
and a shortened attention span.

8B

DSM-5-TR Sleep-Wake Disorders

Categorizes sleep-wake disorders into 10 groups: insomnia, breathing-related sleep disorders, substance/medication-induced sleep disorder, and circadian rhythm sleep-wake disorders.
Circadian rhythm sleep disorders are characterised by a persistent pattern of sleep disruption due to a misalignment between the circadian rhythm and the sleep-wake schedule.
These disorders can cause excessive sleepiness, insomnia, distress, or impairment of functioning.

Three types of circadian rhythm sleep disorders:

Delayed Sleep Phase Syndrome
Advanced Sleep Phase Disorder and shift work.
Treatment involves bright light therapy, which resets the sleep-wake cycle and promotes wakefulness.
The ideal light source can be a safe but artificial source, a desk lamp, floor lamp, visor hat with attached light, or natural sunlight.

(DSPS) Delayed Sleep Phase Syndrome

DSPS is a circadian rhythm sleep disorder characterised by a delay in sleep onset and awakening.
The delay is usually for two or more hours, leading to a person falling asleep later than what is conventionally accepted.
This delay results in a need to wake up later than required for adequate sleep.
The delay contributes to a sleep disorder when a person cannot achieve their recommended amount of sleep due to work, school, or other commitments.
DSPS typically results in a shifted circadian rhythm, preventing a person from falling asleep at a more acceptable time.
Diagnosis requires symptoms for more than three months.

Delayed Sleep Phase Syndrome (DSPS) Risk Factors

Longer than average circadian period and increased light sensitivity are predisposing factors.
Sensitivity to evening light may delay night-time signals to the suprachiasmatic nucleus, affecting melatonin release.
Less sensitivity to morning light results in less melatonin release.
Lifestyle adjustments can reduce sleep deprivation and symptoms.
Bright light therapy can help shift circadian rhythm to a more suitable time.

Early Morning Light Exposure and Sleep Cycle Reset

Reduces melatonin release earlier in the morning.
Resets circadian rhythm, promoting sleepiness.
Requires limiting night-time light exposure and gradually increasing bedtime.

Advanced Sleep Phase Disorder (ASPD)

A circadian rhythm sleep disorder characterised by an advance in sleep onset and awakening timing.
Individuals may fall asleep two or more hours earlier than desired, leading to earlier waking times.
Example: Sleeping from 8 p.m. to 4 a.m. instead of 10 p.m. to 6 a.m.
Attempts to adhere to a more reasonable, later bedtime result in an early wake time due to the shift in circadian rhythm.

Adverse Light Exposure and ASPD

Adverse light exposure can maintain advanced circadian rhythm, affecting sleep and wake patterns.
Early bedtime and wake times prevent exposure to evening low and morning bright light signals, perpetuating the disorder.
Symptoms of ASPD become more severe when work or social demands disrupt the natural sleep-wake cycle.
Adjusting daytime sleep and wake schedules can lead to stable sleep patterns and reduced symptoms.
Bright light therapy can help shift circadian rhythm to a more appropriate time, reducing sleepiness and resetting the sleep-wake cycle.

Shift Work

Shift work can cause a circadian rhythm sleep disorder, especially in professions like healthcare, hospitality, factory work, transport, and travel.
This disorder results in distress due to excessive sleepiness at work and impaired sleep at home after shift.
It affects 5-10% of the population working during nights, especially at the middle-aged stage.
Consequences include poor performance, interpersonal problems, increased risk of accidents, and poor mental wellbeing.
Prolonged shift work is linked to physical health problems like gastrointestinal disorders, cardiovascular disease, diabetes, and cancer.
Symptoms reduce when a person spends longer on one shift rotation before changing.
Ideally, shift forward from morning to afternoon shift, to evening shift.
Bright light therapy can help adjust circadian rhythm to suit work schedules.

Improving Health through Sleep and Exercise

Healthy diet, regular exercise, and adequate sleep are the three pillars of health.
Poor sleep patterns are linked to physical health issues like diabetes, weight problems, hypertension, cardiovascular disease, and mental health issues like depression, bipolar disorder, anxiety disorders, and schizophrenia.
Despite these health risks, many prioritise sleep less than healthy eating and exercise.
Improving sleep hygiene involves avoiding devices and caffeine before bed, following a wind-down bedtime routine, minimising light and noise, ensuring a cool temperature, and having comfortable bedding.

Sleep Hygiene and Wellbeing

Consistent sleep hygiene promotes faster and quality sleep.

Zeitgebers

environmental cues like light, temperature, and eating patterns.
These cues synchronise and regulate the body's circadian rhythm.
They can shift the 24-hour sleep-wake cycle, improving mental wellbeing.

Daylight

Daylight, both direct and indirect, is the primary zeitgeber for human circadian rhythm.
Light's detection by the suprachiasmatic nucleus in the brain influences the release of melatonin by the pineal gland.
Increased light levels suppress melatonin production, promoting wakefulness.
Decreased light levels increase melatonin release, promoting sleepiness.

Circadian System and Artificial Lighting

The Circadian system's ability to resynchronize daily with the external environment is evolutionary.
Artificial lighting allows 24-hour access to light, enabling nighttime activities previously restricted to daytime.
Blue light, emitted from smartphones, computers, TVs, LEDs, and the Sun, significantly influences circadian rhythm.
Blue light inhibits melatonin, affecting sleep quality and quantity.
Unintentional blue light exposure can lead to sleep disorders and poor mental and physical wellbeing.

Influence of Light on Sleep and Wellbeing

Individuals can influence their light exposure to shift disrupted sleep-wake cycle and improve mental wellbeing.
Healthy individuals should expose themselves to natural daylight in the morning and throughout the day.
Blocking out artificial light, especially blue light, at night before sleep can reinforce a regular sleep-wake cycle.
Ways to avoid blue light include using in-built screen filters, 'night mode' settings, reducing screen brightness, or not using screens before bed.
Dimming LED room lights, using red or orange lamps, or using glasses blocking blue light can also reduce sleep disturbances.
Circadian rhythm sleep disorders can be managed by strategically using light.
Night shift workers can increase blue light during work hours and minimize daylight exposure during sleep.
Blue light can enhance wellbeing by keeping individuals alert, improving performance, and mood.
Factors to consider include duration, intensity, color, and time of day.
Exposure to daylight during waking hours and strategic use of blue light can regulate the sleep-wake cycle, leading to restful sleep and positive mental wellbeing.
Emerging theories suggest light affects other brain areas that regulate mood, independent of its impact on the sleep-wake cycle.

Improving Sleep-Wake Cycle through

Temperature

Temperature is a zeitgeber for sleep-wake cycle, regulated by the suprachiasmatic nucleus.
Body temperature decreases in the early evening, with sleep onset occurring when core body temperature is at its highest.
Increased blood flow to the skin causes skin warming, reducing body temperature.
The lowest body temperature occurs about 2 hours after sleep onset.
Skin warming initiates sleep, supported by bedding use, animal curling up, and nest building.
Neural pathways promoting NREM sleep and body cooling are linked.
Increase in melatonin coincides with decrease in core body temperature leading to sleep onset.

Sleep Orientation and Microclimate

Ideal room temperature for sleep onset: 19–21°C.
Ideal skin and bed microclimate for sleep: 31–35°C.
Strategies include windows, fans, appropriate bedding, sleepwear, curtains, and mattress and pillow.
Elderly individuals may benefit from these strategies due to difficulties with thermoregulation.
Skin warming can restore age-related decrease in deep sleep and reduce early morning awakening.
Temperature regulation improves sleep-wake cycle consistency and mental wellbeing.

Eating and Drinking Patterns and Circadian Rhythm

The suprachiasmatic nucleus is the primary circadian rhythm keeper, influenced by light and food intake.
It is not significantly impacted by meal timing, but can be affected by severe food deprivation, calorie restriction, and perceived starvation.
Other peripheral body clocks, acting alongside the suprachiasmatic nucleus, receive daily resetting signals from the suprachiasmatic nucleus and are influenced by other zeitgebers, including meal timing.
For optimal energy balance, peripheral clocks should be synchronised with the suprachiasmatic nucleus.
Altering meal timing to the inactive, dark phase of the 24-hour cycle can disrupt the normal functioning of the body clock, disrupting the suprachiasmatic nucleus.

Shifting Circadian Rhythms and Metabolic Disorders

Shifting circadian rhythm due to food consumption and low light exposure can disrupt the sleep-wake cycle.
Shift workers and those with constant food availability may be affected by conflicting meal timings.
Modern lifestyle influences, such as constant food availability, reduced sleep, longer active hours, and socially dictated behaviour, can lead to metabolic disorders like weight gain, obesity, and type 2 diabetes.
Eating meals within 3-4 hours of sleep onset can negatively affect sleep quality and increase onset time and awakenings.
Increased caffeine consumption correlates with increased sleep problems, including morning tiredness, increased awakenings, restless sleep, and reduced sleep quality.
Dietary interventions can help reduce health problems and improve the sleep-wake cycle.
Limiting caffeine intake later in the day and not eating right before sleep can improve sleep onset and quality.
Resetting mealtimes during the active, light phase of the day and leaving a long fasting window during the inactive phase of night can help resynchronize peripheral clocks with the suprachiasmatic nucleus.