The Importance of Sleep

The Cost of Ineffective Sleep

Four in ten Australians suffer from inadequate sleep, which translates to about 7.4 million people according to a 2017 report. This inadequate sleep can stem from various factors such as work or social commitments, impacting the opportunity to get sufficient sleep, or from sleep disorders like sleep apnea and insomnia.

The consequences of inadequate sleep include:

• Economic impact.
• Health impact: Increased risk of type 2 diabetes, cardiovascular disease, coronary heart disease, excess weight or obesity, and mortality, especially in activities like drowsy driving.

Defining Inadequate Sleep

Inadequate sleep is defined not only by quantity (minutes of sleep) but also by quality.

Markers of sleep quality include:

• Sleep latency: Time taken to transition from being awake to sleep.
• Wake after sleep onset: Total time spent awake after falling asleep.
• Number of awakenings per night.
• Sleep efficiency: Ratio of sleep duration to time spent in bed. A good sleep efficiency is above 85%.

Regarding sleep quantity:

• Short sleepers: Adults getting six hours of sleep or less.
• Long sleepers: Adults sleeping over ten hours.
• Typical sleep duration: Generally, seven to nine hours is considered typical.

Sleep need differs for everyone.

Prevalence of Inadequate Sleep

• Short Sleepers: 20-24% of individuals in the 30-60 age range experience short sleep.
• Sleep disorders:
  • Poor Sleep Quality: Approximately 20-29% of individuals.
  • Obstructive Sleep Apnea: Around 5% of adults.
  • Insomnia: About 26% in young adults (18-24), with a similar prevalence across the lifespan.
  • Restless Legs Syndrome: About 18-20% prevalence in the community.

Data is scarce for the Aboriginal and Torres Strait Islander community; however, available data indicates:

• Short sleepers: 16%.
• Long sleepers: 41% sleep nine hours or more per night, compared to 26% of non-Indigenous individuals.

Causes and Effects of Insufficient Sleep

Causes:

• Lifestyle factors: Work and socialisation often take precedence over sleep.
• Sleep disorders: Insomnia and narcolepsy.

Effects:

• Health perspective.
• Performance perspective.

Sleep Disorders

Insomnia

Classification from the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders):

Characterized by dissatisfaction with sleep quality or quantity, associated with one or more of the following symptoms:

• Difficulty initiating sleep.
• Difficulty maintaining sleep (waking for extended periods).
• Early morning awakenings.

The condition typically needs to persist for a certain period (e.g., three months) to be classified as a sleep disorder.

Insomnia can coexist with other conditions such as depression, creating a need to address sleep problems directly to promote mental health.

Cognitive Behavioral Therapy for Insomnia (CBT-I)

CBT-I focuses on restructuring thoughts, feelings, and behaviors contributing to insomnia. It addresses anxiety, stress, and cognitive arousal that make falling asleep difficult.

Components of CBT-I include:

• Sleep restriction: Shortening the sleep period to promote more efficient sleep.
• Cognitive restructuring.
• Sleep hygiene practices.
• Relaxation techniques.
• Stimulus control.

Iatrogenic Insomnia: Can be caused by the prescription of hypnotic medications like benzodiazepines by GPs, leading to reliance and tolerance. CBT-I is a treatment to avoid reliance.

Narcolepsy

Narcolepsy is distinguished from insomnia by:

• Excessive daytime sleepiness.
• Cataplexy: Complete loss of muscle tone (not just weakness) in an area, such as dropping a cup, drooping of an eyelid, or loss of use of an arm. Can also be complete caliplexy or total caliplexy where there's a slumping of the body that looks like a sleep like state
• Sleep paralysis.
• Sleep-related hallucinations.

Biological Basis: In certain individuals, narcolepsy is caused by the loss of hypocretin (orexin) in the brain, a wake-promoting hormone released by the lateral hypothalamus.

Characteristics:

• Individuals with narcolepsy fall into REM sleep first (sleep onset REM).
• Short sleep latency (time taken to get to sleep).
• Sleep attacks (falling into sleep).
• Phenomena related to sleep paralysis and hypnagogic hallucinations (dreaming in wake).

Effects of Insufficient Sleep on Performance

Sustained Attention:

Studied in experimental sleep deprivation protocols. This graph demonstrates the effects of sleep deprivation on sustained attention, measured by mean speed as a percentage of baseline. The x-axis represents days, and the y-axis represents performance relative to baseline (100%).

• y = mx + b Where: y = performance, x = days, m = slope, b = y-intercept

Over an 83-hour Sleep Deprivation:

• Day 1: Slight decrease in performance.
• Night 1: Large decrease in reaction time performance due to increased homeostatic sleep pressure and low circadian alerting signal.
• Day 2: Improvement in performance due to circadian influence, but not back to baseline.
• Pattern repeats: Steep decline at night, increase during the day.

Following sufficient rest and recovery, individuals experience a rebound in slow-wave sleep and return to baseline levels.

Blood Alcohol Concentration (BAC) Comparison

• Being awake for 17-19 hours: Impairment comparable to a BAC of 0.05 (legal limit in Australia).
• Being awake for 21-24 hours: Impairment comparable to a BAC of approximately 0.08-0.1 (legal limit in some other countries).