A 17-year-old man presents to his primary care physician concerned about excessive sleepiness that has persisted his entire life. He notes that he has been having difficulty with his job as a waiter because he often falls asleep suddenly during the day. He also experiences a sensation of dreaming as he goes to sleep even though he still feels awake. He sleeps about 10 hours per day and still feels tired throughout the day. The patient has even reported driving into a tree once as he fell asleep while driving. The patient often stays up late at night working on the computer. Physical exam demonstrates an obese young man who appears tired. His oropharynx demonstrates high palatal ridges and good dental hygiene. Which of the following is the best next step in management?

Order sleep study with Multiple Sleep Latency Test

Recommend scheduling regular naps and more time for sleep at night

Start a selective serotonin reuptake inhibitor

Begin inhibitor of dopamine reuptake

Continuous positive airway pressure at night

A 20-year-old female presents to student health at her university for excessive daytime sleepiness. She states that her sleepiness has caused her to fall asleep in all of her classes for the last semester, and that her grades are suffering as a result. She states that she normally gets 7 hours of sleep per night, and notes that when she falls asleep during the day, she immediately starts having dreams. She denies any cataplexy. A polysomnogram and a multiple sleep latency test rule out obstructive sleep apnea and confirm her diagnosis. She is started on a daytime medication that acts both by direct neurotransmitter release and reuptake inhibition. What other condition can this medication be used to treat?

Attention-deficit hyperactivity disorder

A 40-year-old man with a past medical history of major depression presents to the clinic. He is interested in joining a research study on depression-related sleep disturbances. He had 2 episodes of major depression within the last 2 years, occurring once during the summer and then during the winter of the other year. He has been non-compliant with medication and has a strong desire to treat his condition with non-pharmacological methods. He would like to be enrolled in this study that utilizes polysomnography to record sleep-wave patterns. Which of the following findings is likely associated with this patient’s psychiatric condition?

Associated with a seasonal pattern

An 8-year-old girl is brought to the physician by her parents for a 10-month history of disturbing dreams and daytime sleepiness. She has difficulty falling asleep and says she sometimes sees ghosts just before falling asleep at night. She has had a 7-kg (15-lb) weight gain during this period despite no changes in appetite. She is alert and oriented, and neurologic examination is unremarkable. During physical examination, she spontaneously collapses after the physician drops a heavy book, producing a loud noise. She remains conscious after the collapse. Polysomnography with electroencephalogram is most likely to show which of the following?

Decreased delta wave sleep duration

A 21-year-old man presents to the clinic complaining of feeling tired during the day. He is concerned as his grades in school have worsened and he does not want to lose his scholarship. Upon further questioning, the patient describes frequently experiencing a dreamlike state before falling asleep and after waking up. He also has frequent nighttime awakenings where he finds himself unable to move. He denies snoring. The patient does not drink alcohol or abuse any other drugs. The patient's BMI is 21 kg/m2, and his vital signs are all within normal limits. What is this patient's diagnosis?

Delayed sleep phase syndrome (DSPS)

Parasomnias for USMLE Step 2 CK: High-Yield Psychiatry Lessons

Parasomnias - Unwanted Night Guests

NREM Arousal Disorders (Slow-wave N3 sleep; first half of night)
- Sleepwalking (Somnambulism): Complex motor behaviors. Amnesia for event.
- Sleep Terrors: Abrupt terror, screaming, autonomic arousal (↑HR, ↑RR). Inconsolable, amnesia.
REM-Related Parasomnias (Second half of night; dream recall)
- Nightmare Disorder: Recurrent frightening dreams. Recalls details.
- REM Sleep Behavior Disorder (RBD): Dream-enacting behaviors, often violent. Lack of normal muscle atonia.

⭐ RBD is a strong predictor of future neurodegeneration (e.g., Parkinson disease, Lewy body dementia).

The Sleep Cycle: NREM and REM Stages

NREM Disorders - Sleepwalking & Screaming

Pathophysiology: Disorders of arousal from non-rapid eye movement (NREM) sleep, specifically stage N3 (slow-wave). Occur in the first ⅓ of the night.
Core Features: Incomplete awakenings, unresponsiveness to comfort, and anterograde amnesia for the event. Eyes may be open.
Sleepwalking (Somnambulism):
- Complex motor behaviors (e.g., walking, eating, leaving the house).
- Primary concern is risk of injury.
Sleep Terrors (Pavor Nocturnus):
- Sudden, terrifying screams with significant autonomic arousal (tachycardia, tachypnea, diaphoresis).
- Child appears terrified and is inconsolable.
Management:
- Primary: Reassurance and safety measures (lock doors/windows, remove hazards).
- Pharmacotherapy (if severe/injurious): Low-dose benzodiazepines.

⭐ Key Distinction: Unlike nightmares (REM sleep), patients have no recall of sleep terror or sleepwalking episodes and typically occur earlier in the night.

REM Disorders - Acting Out Dreams

Pathophysiology: Characterized by the loss of normal muscle atonia during REM sleep, leading to dream-enacting behaviors.
Clinical Picture: Patients physically and often violently act out vivid dreams. They can be awakened easily and will recall the dream. Common in men > 50 years old.
Diagnosis: Polysomnography (PSG) demonstrates REM sleep without atonia.
Treatment:
- Ensure environmental safety (remove weapons/dangerous objects from bedroom).
- Clonazepam (low-dose) is first-line.
- Melatonin is an alternative.

Polysomnography: Normal REM Sleep vs. REM Behavior Disorder

⭐ High-Yield: RBD is a major prodromal symptom for neurodegenerative diseases. Up to 80% of patients will develop an α-synucleinopathy, such as Parkinson disease or Lewy Body Dementia, often within a decade.

📌 Rapid Eye Movements become Real Enacted Movements.

Workup & Treatment - Taming the Night

Workup
- Begin with a detailed sleep history from the patient and bed partner.
- Rule out secondary causes: medications, substances, other sleep disorders (e.g., OSA).
- Polysomnography (PSG): Gold standard to confirm diagnosis, especially differentiating NREM disorders from nocturnal seizures and identifying REM sleep without atonia in RBD.
Treatment
- Foundation: Reassurance and strict safety precautions (e.g., removing dangerous objects, securing windows).
- NREM Parasomnias: If severe/injurious, consider low-dose benzodiazepines (e.g., Clonazepam 0.5-2 mg).
- REM Sleep Behavior Disorder (RBD): Clonazepam is first-line; Melatonin is a common alternative.

⭐ REM Sleep Behavior Disorder (RBD) is a powerful predictor for future development of an α-synucleinopathy, such as Parkinson's disease or Lewy body dementia.

Polysomnography: Normal REM sleep vs. RBD

NREM parasomnias (sleepwalking, sleep terrors) occur in the first half of the night during N3 sleep, with no memory of the event.

REM sleep behavior disorder (RBD) involves acting out dreams in the second half of the night and strongly predicts future α-synucleinopathies (e.g., Parkinson's).

Nightmare disorder also occurs during REM sleep but features distressing dreams without motor activity and with full recall upon awakening.

Management for all parasomnias prioritizes safety measures and reassurance.

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Parasomnias