Rest and Sleep: Physiology, Disorders, and Health Implications

Ch 35: Rest & Sleep

Definitions and Concepts

Rest and sleep are essential physiological processes that restore mental and physical function. Understanding their differences and roles is crucial for maintaining personal health.

• Rest: A state of decreased activity, leading to feelings of refreshment.

• Sleep: A state of rest with altered consciousness and relative inactivity, part of the sleep–wake cycle.

• Wakefulness: A period of mental activity and energy expenditure.

Example: After a full night's sleep, individuals typically feel restored and alert, ready for daily activities.

Physiology of Sleep

Neural Regulation

Sleep is regulated by complex neural mechanisms involving several brain regions:

• Reticular Activating System (RAS): Facilitates reflex and voluntary movements; controls alertness.

• Bulbar Synchronizing Region: Works with the RAS to regulate sleep.

• Hypothalamus: Acts as the control center for sleeping and waking.

Stages of Sleep

NREM and REM Sleep

Sleep is divided into two main types: Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) sleep, each with distinct characteristics.

• NREM Sleep: Consists of four stages:

  • Stage I: Transitional phase between wakefulness and sleep.

  • Stage II: Light sleep; person can be aroused with relative ease (comprises 5%–50% of sleep).

  • Stages III and IV: Deep sleep (delta sleep); arousal is difficult (10% of sleep).

• REM Sleep: Accounts for 20%–25% of nightly sleep. Characterized by increased pulse, respiratory rate, blood pressure, metabolic rate, and body temperature, with decreased skeletal muscle tone and deep tendon reflexes.

Example: Most dreaming occurs during REM sleep, which is also important for memory consolidation.

Sleep Cycle

Normal Progression

During a typical night, individuals cycle through NREM and REM sleep in a predictable pattern:

• Progress through four stages of NREM sleep.

• Reverse from stage IV to III to II, then enter REM sleep instead of returning to stage I.

• After REM, re-enter NREM at stage II and continue cycling.

Effects of Insufficient Sleep

Health Consequences

Inadequate sleep can have significant effects on health and well-being:

• Impaired growth and development in children.

• Increased risk of obesity in children and adults.

• Hormonal changes: decreased leptin (satiety hormone) and increased ghrelin (hunger hormone), promoting overeating.

Example: Chronic sleep deprivation is linked to weight gain and metabolic disorders.

Developmental Patterns of Sleep

Age-Related Changes

Sleep needs and patterns vary across the lifespan:

• Newborns and Infants: Require the most sleep, with frequent cycles.

• Toddlers, Preschoolers, School-aged Children: Gradual decrease in total sleep time; increased need for routine.

• Teenagers: Often experience delayed sleep phase and insufficient sleep due to lifestyle.

• Young, Middle-aged, and Older Adults: Sleep becomes lighter and more fragmented with age.

Factors Affecting Rest and Sleep

Influencing Elements

Multiple factors can impact sleep quality and duration:

• Developmental considerations

• Motivation

• Culture

• Lifestyle and habits

• Environmental factors

• Psychological stress

• Illness

• Medications

Lifestyle and Habits

• Activity and Exercise: Promote fatigue and relaxation, increasing both REM and NREM sleep.

• Dietary Habits:

  • L-tryptophan: An amino acid that promotes sleep.

  • Carbohydrates: Small protein snack with complex carbohydrates before bed can improve sleep.

  • Alcohol: Large quantities limit REM and delta sleep.

  • Caffeine: Blocks adenosine, preventing drowsiness.

  • Nicotine: Associated with poorer sleep quality.

Example: Toast (a carbohydrate) is an appropriate bedtime snack to promote sleep.

Psychological Stress

• Illness or life situations can cause stress, disturbing sleep.

• Decreased REM sleep leads to increased anxiety and stress.

Illnesses Associated With Sleep Disturbances

• Gastroesophageal reflux

• Coronary artery diseases

• Epilepsy seizures

• Liver failure and encephalitis

• Hypothyroidism

• End-stage renal disease

Medications That Affect Sleep

• Benzodiazepines

• Amphetamines

• Antidepressants

• Diuretics

• Antiparkinsonian drugs

• Antihypertensives

• Steroids

• Decongestants

• Caffeine

• Asthma medications

Classification of Sleep Disorders

ICSD Categories

The International Classification of Sleep Disorders (ICSD) includes:

• Insomnia

• Sleep-related breathing disorders

• Central disorders of hypersomnolence

• Circadian rhythm sleep–wake disorders

• Parasomnias

• Sleep-related movement disorders

• Other sleep disorders

Insomnia

• Difficulty falling asleep, intermittent sleep, or difficulty maintaining sleep despite adequate opportunity.

• Prevalence: 30%–35% of U.S. adults.

• Often related to circadian rhythm disruptions or depression.

• May be short-term or chronic.

Obstructive Sleep Apnea (OSA)

• Characterized by five or more obstructive respiratory events per hour during sleep.

• Includes apnea (absence of breathing), hypopnea (diminished breathing), and respiratory effort-related arousals.

• Symptoms: Sleepiness, fatigue, insomnia, snoring, gasping for air, and observed apnea.

Central Disorders of Hypersomnolence

• Idiopathic Hypersomnia: Excessive sleep, especially during the day.

• Narcolepsy: Excessive daytime sleepiness and sudden sleep attacks; up to 70% experience cataplexy (sudden loss of muscle tone).

Circadian Rhythm Sleep–Wake Disorders

• Chronic or recurrent disruption of the sleep–wake cycle due to misalignment between internal circadian rhythm and external demands.

• Symptoms: Insomnia or excessive sleepiness, distress, or impairment lasting at least 3 months (except jet lag).

Parasomnias

• Somnambulism: Sleepwalking.

• REM Sleep Behavior Disorder (RBD): Acting out dreams during REM sleep.

• Sleep Terrors: Episodes of screaming or intense fear during sleep.

• Nightmare Disorder: Frequent, vivid nightmares.

• Sleep Enuresis: Bedwetting.

• Sleep-Related Eating Disorder: Eating during partial arousals from sleep.

Sleep-Related Movement Disorders

• Restless Legs Syndrome (RLS)/Willis–Ekbom Disease (WED): Unpleasant sensations in the legs and an urge to move them, affecting up to 15% of the population, especially middle-aged and older adults.

• Nonpharmacologic treatments are often recommended.

Assessment of Sleep

Obtaining a Sleep History

• Nature and cause of the problem

• Related signs and symptoms

• Onset, frequency, and duration

• Impact on daily living

• Severity and coping strategies

Screening Tools

• Sleep Diary: Records sleep patterns and influencing factors.

• Epworth Sleepiness Scale: Measures daytime sleepiness.

• Pittsburgh Sleep Quality Index (PSQI): Assesses sleep quality.

• STOP-Bang Questionnaire: Screens for OSA.

• Stanford Sleepiness Scale: Rates current sleepiness.

Information Recorded in a Sleep Diary

• Bedtime and time attempting to sleep

• Time of sleep onset

• Awakenings and resumption of sleep

• Wake time in the morning

• Stressors, food, drink, medications, activities before bed, and worries

Sleep Characteristics to Assess

• Restlessness

• Sleep postures and activities

• Snoring

• Leg jerking

Physical Assessment Findings

• Energy level

• Facial and behavioral characteristics

• Physical signs suggestive of sleep problems

Interventions and Treatments

Nursing Interventions to Promote Sleep

• Prepare a restful environment

• Promote bedtime rituals

• Offer appropriate snacks and beverages

• Promote relaxation and comfort

• Respect normal sleep–wake patterns

• Schedule care to avoid disturbances

• Use medications judiciously

• Educate about rest and sleep

Treatment for Dyssomnias

• Pharmacologic Therapy: Sedatives and hypnotics.

• Nonpharmacologic Therapy:

  • Cognitive Behavioral Therapy (CBT)

  • Progressive muscle relaxation

  • Stimulus control

  • Sleep restriction and sleep hygiene

  • Biofeedback and relaxation therapy

Key Table: Sleep Disorders Classification

Category	Examples	Main Features
Insomnia	Primary insomnia	Difficulty falling or staying asleep
Sleep-related breathing disorders	Obstructive sleep apnea	Breathing interruptions during sleep
Central disorders of hypersomnolence	Narcolepsy, idiopathic hypersomnia	Excessive daytime sleepiness
Circadian rhythm sleep–wake disorders	Shift work disorder, jet lag	Misalignment of sleep–wake schedule
Parasomnias	Sleepwalking, night terrors	Abnormal behaviors during sleep
Sleep-related movement disorders	Restless legs syndrome	Unpleasant sensations and urge to move limbs

Key Equations and Hormones

• Leptin and Ghrelin: Hormones regulating appetite and sleep.

Leptin: Signals satiety to the brain.

Ghrelin: Stimulates appetite.

Sleep deprivation lowers leptin and raises ghrelin, increasing hunger and risk of obesity.

Equation (Hormonal Balance and Sleep):

$\text{Sleep Deprivation} \rightarrow \downarrow \text{Leptin} + \uparrow \text{Ghrelin} \rightarrow \uparrow \text{Appetite} \rightarrow \uparrow \text{Obesity Risk}$

Additional info: Sleep hygiene practices, such as maintaining a regular sleep schedule, limiting screen time before bed, and creating a comfortable sleep environment, are effective nonpharmacologic interventions for improving sleep quality.