II. Definitions

  1. Delayed Sleep Phase Disorder (Delayed Sleep-Wake Phase Disorder)
    1. Circadian rhythm disorder with late sleep onset as well as late wake-up time
    2. Results in excessive Daytime Sleepiness and Insomnia (difficulty initiating sleep)

III. Epidemiology

  1. Typically affects teens and young adults
  2. Prevalence: 7-16% of adolescents
  3. Onset in teen years with peak Incidence in early 20s
  4. Family History of Delayed Sleep Phase in 40% of patients

IV. Physiology

  1. Human clock is located within the suprachiasmatic nucleus (Hypothalamus)
    1. Regulates the circadian rhythm
    2. Most affected by light exposure
    3. Also impacted by meals, Exercise and other Activities of Daily Living
  2. Light exposure (media screens included) prior to bedtime inhibits Melatonin secretion
    1. Decreased Melatonin delays sleep onset

V. Symptoms

  1. Shifted sleep schedule by at least 2 hours later that typical acceptable times
    1. Persistent pattern for >3 months
  2. Patient has a "night owl" sleep pattern
    1. Difficulty initiating sleep (e.g. prior to 1-2 am)
    2. Difficulty waking up by typical awakening times (e.g. prior to noon)
  3. Provocative
    1. Evening light exposure
    2. Lack of morning light exposure

VI. Diagnostics

  1. Sleep diary
    1. Keep diary for 7-14 days including weekends
    2. Log sleep times before and after intervention
  2. Actigraphy monitoring for at least 1 week
    1. Accelerometer monitors patients overnight movement
    2. Calculates actual patient sleep time

VII. Diagnosis

  1. Late sleep onset with difficulty initiating sleep AND
  2. Late wake-up time AND
  3. Excessive Daytime Sleepiness and functional Impairments for at least 3 months

VIII. Management

  1. See Sleep Hygiene
  2. See Insomnia
  3. Overall strategy is to realign circadian rhythm and sleep-wake cycle to a school or work schedule
    1. Requires sticking to a schedule of bedtime and wake times
    2. Relies on good Sleep Hygiene
  4. Melatonin 3 to 5 mg orally at least 1.5 hours prior to desired bedtime
    1. Mundey (2005) Sleep 28(10): 1271-8 [PubMed]
  5. Limit bright light exposure prior to bedtime
    1. Avoid computers, handheld devices, television watching before bed
  6. Bright Light Therapy on awakening
    1. Exposure to 2000 to 2500 lux for at least 30 minutes up to 1-2 hours after awakening
    2. Sunlight exposure during play or Exercise is even more effective
  7. Transitioning to optimal sleep timing
    1. Shift Melatonin/light exposure 1 hour earlier every 5-7 days until desired schedule is achieved

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