Chapter 8: Eating and Sleep–Wake Disorders

Major Types of Eating Disorders

• Bulimia Nervosa (BN)

  • Out-of-control binge episodes → compensatory behaviors (self-induced vomiting, laxatives, diuretics, excessive exercise, fasting).
  • DSM-5: binge ≥ once/week for ≥ 3 mo; self-evaluation unduly influenced by shape/weight; not exclusively during Anorexia.
  • Medical risks: salivary-gland enlargement, dental enamel erosion, esophageal tears, electrolyte imbalance → \text{arrhythmia},\,\text{seizures},\,\text{renal failure}; calloused fingers.
  • Psych comorbidity: anxiety (~81 %), mood disorders (50–70 %), substance use (~37 %).
  • Course: chronic if untreated; 50–67 % symptomatic at 5-yr follow-up.

• Anorexia Nervosa (AN)

  • Restriction of energy intake → significantly low weight (≤ 85 % expected or BMI ≈ 15.8 at tx). Intense fear of gaining weight; body-image disturbance.
  • Subtypes (DSM-5 past 3 mo): Restricting vs. Binge-Eating/Purging.
  • Highest mortality of any psych disorder (up to 20 %; suicide 20–30 %).
  • Medical risks: amenorrhea, dry skin, lanugo, cardiovascular problems, osteoporosis, electrolyte imbalance.
  • Psych comorbidity: anxiety (esp. OCD), mood (~71 %), substance use.

• Binge-Eating Disorder (BED)

  • Recurrent binges without compensatory behavior + marked distress; 3+ of rapid eating, uncomfortable fullness, absent hunger, eating alone, guilt/disgust.
  • More common in males, later onset, better prognosis; ~20 % of obese in weight-loss programs, 50 % of bariatric candidates.
  • 33 % binge to manage negative affect → more severe.

Epidemiology & Course

• Lifetime prevalence (Hudson 2007): AN 0.6 %, BN 1 %, BED 2.8 % (female > male ≈ 3 : 1, except BED closer).
• Age of onset: 18–21 y (BN/AN), BED later; earlier trend emerging.
• Cultural: Historically Western; now globalizing (China, Japan). 90 % severe cases = young females in competitive contexts.
• Ethnic trends: Past lower rates in African-American women; gap narrowing.
• Risk factors: childhood obesity, early dieting, perfectionism, ‘thin-ideal’ internalization, familial emphasis on appearance.

Etiology (Integrative Model)

• Social/Cultural: thin-ideal media, peer cliques, parental modeling, pressure in ballet/athletics, pro-ana/mia websites.
• Biological: genetic heritability ≈ 50 %; serotonergic dysregulation; ovarian hormones modulate binge risk; hypothalamic involvement; perfectionism & emotional instability may be inherited.
• Psychological: low self-esteem, anxiety focused on weight, distorted body image, mood intolerance, rigid control vs. impulsivity.

Treatment of Eating Disorders

• BN: CBT-E (20 wks) = gold standard; targets binge-purge cycle, shape/weight overvaluation; 65 % remission post-tx. IPT slower but catches up. SSRIs adjunct (reduce binge/purge ~50 %).
• BED: CBT (individual or guided self-help) & IPT effective; rapid responders better outcome. Meds (SSRIs, lisdexamfetamine) modest. Weight-loss only insufficient.
• AN:
  • Phase 1: restore weight (inpt if < 75 % IBW); phase 2: CBT-E, family-based therapy (FBT) for adolescents; 49 % remission w/ FBT vs. 23 % indy therapy.
  • No proven meds; fluoxetine ineffective for relapse prevention.
• Prevention: selective programs (e.g., Body Project, Student Bodies) reduce thin-ideal internalization; internet delivery effective.

Obesity

• BMI ≥ 30. U.S. prevalence 37.7 % (2013-14); children ≥ 95th %ile = 16.9 %.
• Health risks: CVD, T2-DM, hypertension, stroke, cancers.
• Etiology: energy intake > expenditure; genetic (~30 %); toxic environment (cheap caloric food, sedentary tech), night-eating syndrome (6–16 % of obese); binge eating.
• Treatment: self-help diets limited; commercial programs moderate; professional CBT + diet/exercise best; drugs (orlistat, lorcaserin, phentermine/topiramate) limited; bariatric surgery for BMI ≥ 40 → 20–30 % WL, ↓mortality.
• Prevention: policy (tax sugary drinks, remove school vending), choice architecture, parental education.

Sleep–Wake Disorders Overview

• Two classes: Dyssomnias (quantity/quality/timing) & Parasomnias (abnormal events during sleep).
• Polysomnography (PSG) & actigraphy assess sleep; Sleep Efficiency \text{SE} = \frac{\text{time asleep}}{\text{time in bed}}.

Dyssomnias

• Insomnia Disorder: difficulty initiating, maintaining, or nonrestorative sleep ≥ 3 nights/wk for ≥ 3 mo. 1/3 pop reports symptoms yearly. Tx: CBT-I (stimulus control, sleep restriction, cognitive restructuring); short-term hypnotics (zolpidem, temazepam) caution rebound.
• Hypersomnolence Disorder: excessive sleep despite ≥ 7 h main period; treat with stimulants (modafinil).
• Narcolepsy: irresistible sleep attacks + cataplexy, hypocretin deficiency, or REM onset ≤ 15 min. Onset teens; Tx: stimulants (modafinil), sodium oxybate for cataplexy, SSRIs.
• Breathing-Related Sleep Disorders:
  • Obstructive Sleep Apnea Hypopnea (OSA): repeated airway collapse; loud snoring; CPAP, weight loss.
  • Central Sleep Apnea & Sleep-Related Hypoventilation: CNS dysregulation; treat w/ servo-ventilation, meds.
• Circadian Rhythm Sleep–Wake Disorder: misalignment (jet lag, shift-work, delayed/advanced phase). Tx: phase shifts, bright-light therapy, melatonin.

Parasomnias

• NREM Arousal Disorders: Sleep terrors & Sleepwalking; occur first third of night, no dream recall. Tx: safety; scheduled awakenings; benzos if severe.
• Nightmare Disorder: vivid dysphoric dreams during REM; recall & full alertness. Tx: imagery rehearsal therapy, prazosin.
• REM Sleep Behavior Disorder: vocalizations/complex motor activity during REM; associated with neurodegenerative synucleinopathies; clonazepam.
• Restless Legs Syndrome: urge to move legs with unpleasant sensations; Tx: iron, dopamine agonists.

Sleep Treatment Principles

• Sleep hygiene (regular schedule, limit caffeine/alcohol, bedroom only for sleep/sex, exercise early, reduce light/tech).
• Stimulus control superior to hygiene alone; combined CBT-I most effective.

Key Equations & Data

• Mortality risk doubles when BMI ≥ 40 (Figure 8.6).
• Insomnia prevalence ↑ with age; OSA affects ~20 % adults, male > female.
• BED remission 82 % after CBT rapid response vs. 42 % nonrapid.

Clinical Pearls

• AN patients proud of control; BN ashamed → impacts rapport.
• Repeated dieting ↑ risk for obesity (girl dieters 3× risk in 4-yr study).
• CPAP adherence improves with desensitization & partner support.
• Bright-light exposure in morning for phase-delay; evening for phase-advance.