11.1 Sleep Physiology and Disorders

Sleep is crucial for our health and well-being. This section explores the intricate workings of our sleep-wake cycle, including circadian rhythms and the stages of sleep. It's fascinating how our bodies regulate sleep through various hormones and brain chemicals.

We'll also dive into common sleep disorders and their impact on health. From insomnia to sleep apnea, these conditions can seriously affect our physical and mental health. We'll look at how nurses can help patients get better sleep through assessments and treatments.

Sleep-wake cycle physiology

Circadian rhythm and hormonal regulation

• Circadian rhythm regulates the sleep-wake cycle through a 24-hour internal clock controlled by the suprachiasmatic nucleus in the hypothalamus
• Melatonin produced by the pineal gland promotes sleep onset and maintains sleep duration
• Homeostatic sleep pressure increases during wakefulness and decreases during sleep
• Neurotransmitters regulate sleep and wakefulness states
  • GABA inhibits neural activity and promotes sleep
  • Adenosine accumulates during wakefulness and induces sleepiness
  • Orexin promotes wakefulness and regulates transitions between sleep-wake states

Sleep architecture and stages

• Sleep architecture consists of two main types: Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) sleep
• NREM sleep divides into three stages with distinct brain wave patterns
  • N1: Light sleep characterized by theta waves
  • N2: Deeper sleep with sleep spindles and K-complexes
  • N3: Slow-wave sleep with high-amplitude delta waves
• REM sleep associates with vivid dreaming, muscle atonia, and increased brain activity similar to wakefulness
• Sleep cycle progresses through NREM stages before entering REM sleep
  • Each cycle lasts approximately 90-110 minutes
  • Adults typically experience 4-6 cycles per night

Common sleep disorders

Insomnia and sleep-related breathing disorders

• Insomnia involves difficulty falling asleep, staying asleep, or both despite adequate sleep opportunity
  • Acute insomnia lasts less than three months
  • Chronic insomnia persists for three months or longer
• Sleep apnea causes repeated episodes of upper airway obstruction during sleep
  • Obstructive sleep apnea (OSA) results from physical blockage of the airway
  • Central sleep apnea (CSA) occurs when the brain fails to signal breathing muscles
  • Mixed sleep apnea combines features of both OSA and CSA

Hypersomnias and circadian rhythm disorders

• Narcolepsy causes excessive daytime sleepiness and sudden loss of muscle tone (cataplexy)
  • Type 1 narcolepsy includes cataplexy and low cerebrospinal fluid orexin levels
  • Type 2 narcolepsy lacks cataplexy but still presents with excessive daytime sleepiness
• Hypersomnia involves excessive daytime sleepiness and prolonged nighttime sleep
  • Idiopathic hypersomnia lacks the sudden sleep attacks seen in narcolepsy
  • Kleine-Levin syndrome causes recurrent episodes of excessive sleep and altered behavior
• Circadian rhythm sleep-wake disorders misalign the sleep-wake cycle with desired or expected schedules
  • Delayed sleep phase disorder shifts sleep timing later than desired
  • Advanced sleep phase disorder shifts sleep timing earlier than desired
  • Shift work disorder results from working non-standard hours

Movement disorders and parasomnias

• Restless Legs Syndrome (RLS) causes an irresistible urge to move the legs with uncomfortable sensations
  • Symptoms typically worsen in the evening or at night
  • Movement temporarily relieves the discomfort
• Periodic Limb Movement Disorder involves repetitive limb movements during sleep
  • Movements occur every 20-40 seconds and can disrupt sleep
• Parasomnias encompass abnormal behaviors or experiences during sleep
  • Sleepwalking involves complex behaviors during slow-wave sleep
  • Night terrors cause abrupt awakenings with intense fear and autonomic arousal
  • REM sleep behavior disorder results in acting out dreams due to lack of muscle atonia

Sleep disorders' impact on health

Cognitive and mental health effects

• Chronic sleep deprivation impairs cognitive function
  • Decreased attention and concentration (difficulty focusing on tasks)
  • Memory deficits (trouble recalling information or forming new memories)
  • Impaired decision-making abilities (increased risk-taking behavior)
• Sleep disorders exacerbate mental health conditions
  • Depression (persistent low mood, loss of interest in activities)
  • Anxiety (excessive worry, restlessness)
  • Bipolar disorder (mood swings between manic and depressive episodes)

Physical health consequences

• Increased risk of cardiovascular diseases
  • Hypertension (elevated blood pressure)
  • Heart disease (coronary artery disease, arrhythmias)
  • Stroke (ischemic or hemorrhagic)
• Negative effects on metabolic function
  • Obesity (increased body mass index, central adiposity)
  • Insulin resistance (impaired glucose metabolism)
  • Type 2 diabetes (chronic hyperglycemia)
• Weakened immune system
  • Increased susceptibility to infections (common cold, influenza)
  • Prolonged recovery times from illnesses
• Development or worsening of chronic pain conditions
  • Fibromyalgia (widespread musculoskeletal pain)
  • Chronic low back pain
  • Headaches and migraines

Nursing interventions for sleep disorders

Assessment and education

• Conduct comprehensive sleep assessments
  • Sleep history (bedtime routines, sleep environment, daytime symptoms)
  • Sleep diaries (record sleep patterns over 1-2 weeks)
  • Screening tools (Epworth Sleepiness Scale, STOP-BANG questionnaire for sleep apnea)
• Implement sleep hygiene education
  • Maintain consistent sleep schedules (go to bed and wake up at the same time daily)
  • Create a sleep-conducive environment (dark, quiet, cool bedroom)
  • Limit caffeine and alcohol intake, especially before bedtime
  • Encourage regular exercise, but not too close to bedtime

Treatment implementation and monitoring

• Collaborate with healthcare providers to develop individualized treatment plans
  • Referrals to sleep specialists or behavioral therapists as needed
  • Coordinate care among multidisciplinary team members
• Administer and monitor pharmacological interventions
  • Sleep aids (benzodiazepines, non-benzodiazepine hypnotics)
  • Stimulants for narcolepsy or excessive daytime sleepiness (modafinil, methylphenidate)
  • Melatonin supplements for circadian rhythm disorders
• Provide education on non-pharmacological interventions
  • Cognitive-behavioral therapy for insomnia (CBT-I)
  • Relaxation techniques (progressive muscle relaxation, guided imagery)
  • Light therapy for circadian rhythm disorders
• Assist with implementation and management of CPAP therapy for sleep apnea
  • Mask fitting and adjustment
  • Troubleshooting common issues (mask leaks, skin irritation)
  • Monitoring compliance and efficacy
• Monitor and evaluate intervention effectiveness
  • Follow-up assessments (repeat sleep studies, questionnaires)
  • Patient feedback on symptom improvement and quality of life
• Educate patients on treatment adherence and follow-up
  • Importance of consistent use of prescribed interventions
  • Regular follow-up appointments with healthcare providers
  • Self-monitoring of symptoms and sleep patterns