Rest and Sleep: Physiology, Disorders, and Health Implications

Rest, Sleep, and Wakefulness

Definitions and Concepts

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

• Rest: A condition 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: Period of mental activity and energy expenditure.

Physiology of Sleep

Neural Regulation

Sleep is regulated by several brain regions and systems that control alertness and sleep onset.

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

• Bulbar Synchronizing Region: Works with the hypothalamus to regulate sleep and wake cycles.

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

Stages of Sleep

NREM and REM Sleep

Sleep is divided into Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) stages, each with distinct physiological characteristics.

• NREM Sleep: Four stages:

  • Stage I: Transitional stage between wakefulness and sleep.

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

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

• REM Sleep: Occurs after NREM; accounts for 20%–25% of nightly sleep. Physiological changes include increased pulse, respiratory rate, blood pressure, metabolic rate, and body temperature; skeletal muscle tone and deep tendon reflexes are depressed.

Sleep Cycle

A normal sleep cycle involves progression through NREM stages, reversal, entry into REM, and repetition.

• Sequence: NREM I → II → III → IV → III → II → REM → II → III → IV

Effects of Insufficient Sleep

Health Implications

Insufficient sleep can negatively impact growth, metabolism, and overall health.

• May affect normal growth and development in children.

• May increase obesity risk in children and adults.

• Lowers leptin (satiety hormone) and elevates ghrelin (hunger hormone), promoting overeating.

Developmental Patterns of Sleep

Age-Related Differences

Sleep requirements and patterns vary across the lifespan.

• Newborns and infants

• Toddlers

• Preschoolers

• School-aged children

• Teenagers

• Young adults

• Middle-aged adults

• Older adults

Factors Affecting Rest and Sleep

Influencing Variables

Multiple factors can influence sleep quality and quantity.

• Developmental considerations

• Motivation

• Culture

• Lifestyle and habits

• Environmental factors

• Psychological stress

• Illness

• Medications

Lifestyle and Habits

• Activity and exercise promote relaxation and increase both REM and NREM sleep.

• L-tryptophan (amino acid) promotes sleep; small protein snacks with complex carbohydrates before bed improve sleep.

• Large quantities of alcohol limit REM and delta sleep.

• Caffeine blocks adenosine, preventing drowsiness.

• Smoking and nicotine are associated with poorer sleep.

Psychological Stress and Illness

Impact on Sleep

• Stress from illness or life situations disturbs sleep and reduces REM sleep, leading to anxiety.

• Illnesses associated with sleep disturbances include gastroesophageal reflux, coronary artery disease, epilepsy, liver failure, encephalitis, hypothyroidism, and end-stage renal disease.

Medications Affecting Sleep

Drug Effects

• 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) identifies several types of sleep disorders.

• Insomnia

• Sleep-related breathing disorders

• Central disorders of hypersomnolence

• Circadian rhythm sleep–wake disorders

• Parasomnias

• Sleep-related movement disorders

• Other sleep disorders

Insomnia

Definition and Prevalence

Insomnia is characterized by difficulty falling asleep, intermittent sleep, or difficulty maintaining sleep despite adequate opportunity.

• 30%–35% of adults in the U.S. report insomnia.

• More common in those with depression.

• Often related to circadian rhythm disruptions.

• May be short-term or chronic.

Central Disorders of Hypersomnolence

Idiopathic Hypersomnia and Narcolepsy

• 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).

Sleep-Related Breathing Disorders

Obstructive Sleep Apnea (OSA)

OSA is characterized by repeated episodes of obstructed breathing during sleep.

• Five or more obstructive respiratory events per hour.

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

• Symptoms: sleepiness, fatigue, insomnia, snoring, nocturnal respiratory disturbance, observed apnea, gasping for air.

Circadian Rhythm Sleep–Wake Disorders

Characteristics

• Chronic or recurrent disruption of sleep–wake rhythm.

• Caused by alteration or misalignment of internal circadian timing system.

• Associated distress or impairment lasting at least 3 months (except jet lag).

Parasomnias

Types and Features

• Somnambulism: Sleepwalking.

• REM sleep behavior disorder (RBD)

• Sleep terrors

• Nightmare disorder

• Sleep enuresis (bedwetting)

• Sleep-related eating disorder

Sleep-Related Movement Disorders

Restless Legs Syndrome (RLS)

RLS, also known as Willis–Ekbom disease, is a common disorder causing unpleasant sensations in the legs and an urge to move them.

• Affects up to 15% of the population, especially middle-aged and older adults.

• Symptoms: creeping, crawling, or tingling sensations; inability to lie still.

• Nonpharmacologic treatments are available.

Assessment of Sleep Disturbances

Obtaining a Sleep History

• Nature and cause of problem

• Related signs and symptoms

• Onset and frequency

• Impact on daily living

• Severity and treatment options

• Coping strategies and treatment success

Screening Tools

• Sleep Diary

• Epworth Sleepiness Scale

• Pittsburgh Sleep Quality Index (PSQI)

• STOP-Bang Questionnaire (OSA)

• Stanford Sleepiness Scale

Sleep Diary Information

• Time of retiring and attempting to sleep

• Approximate time of sleep onset

• Awakenings and resumption of sleep

• Morning awakening time

• Stressors, food, drink, medications, activities, worries affecting sleep

Sleep Characteristics to Assess

• Restlessness

• Sleep postures

• Sleep activities

• Snoring

• Leg jerking

Physical Assessment Findings

• Energy level

• Facial characteristics

• Behavioral characteristics

• Physical data 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 as needed

• Teach about rest and sleep

Treatment for Dyssomnias

• Pharmacologic therapy: Sedatives, hypnotics

• Nonpharmacologic therapy: Cognitive behavioral therapy (CBT), progressive muscle relaxation, stimulus control, sleep restriction, sleep hygiene, biofeedback, relaxation therapy

Sample Table: Classification of Sleep Disorders

Category	Description
Insomnia	Difficulty falling or staying asleep
Sleep-related breathing disorders	Problems with breathing during sleep (e.g., OSA)
Central disorders of hypersomnolence	Excessive daytime sleepiness (e.g., narcolepsy)
Circadian rhythm sleep–wake disorders	Disruption of sleep–wake timing
Parasomnias	Abnormal behaviors during sleep (e.g., sleepwalking)
Sleep-related movement disorders	Movement disturbances during sleep (e.g., RLS)

Key Terms and Definitions

• Leptin: Hormone signaling satiety; low levels promote eating.

• Ghrelin: Hormone promoting hunger; high levels increase eating.

• Cataplexy: Sudden loss of muscle tone, often seen in narcolepsy.

• Somnambulism: Sleepwalking, a type of parasomnia.

• Restless Legs Syndrome (RLS): Urge to move legs due to unpleasant sensations.

Sample Exam Questions and Rationales

• Stage II of NREM sleep: Person can be aroused with ease.

• Barbiturates, amphetamines, antidepressants: Decrease REM sleep.

• Bedtime snack to promote sleep: Toast (carbohydrate-rich).

• Narcolepsy: Uncontrollable desire to sleep; may experience cataplexy.

• Somnambulism: True; person walks in their sleep.