Sleep Disorders & Pathophysiology Flashcards

Which of the following is a defining characteristic of obstructive sleep apnea (OSA)?

Answer: Recurrent episodes of apnea/hypopnea despite respiratory effort

Obstructive Sleep Apnea (OSA) is characterized by recurrent episodes of partial or complete upper airway collapse during sleep. Despite these obstructions, the individual's respiratory muscles continue to make an effort to breathe. This persistent respiratory effort against a blocked airway is a defining feature that distinguishes OSA from central sleep apnea.

What is the primary pathophysiological mechanism of narcolepsy type 1?

Answer: Autoimmune destruction of hypocretin neurons

Narcolepsy type 1 is primarily caused by the selective loss of hypocretin (orexin) producing neurons in the hypothalamus. This destruction is believed to be an autoimmune process, leading to a severe deficiency of hypocretin, a neuropeptide crucial for regulating wakefulness and REM sleep. The lack of hypocretin results in the characteristic symptoms of excessive daytime sleepiness and cataplexy.

Which sleep disorder is characterized by 'unpleasant leg sensations and an urge to move' that worsens at rest?

Answer: Restless Legs Syndrome (RLS)

Restless Legs Syndrome (RLS) is a neurological disorder defined by an irresistible urge to move the legs, typically accompanied by uncomfortable sensations. These symptoms characteristically begin or worsen during periods of rest or inactivity and are partially or totally relieved by movement. The symptoms are also typically worse in the evening or night, significantly impacting sleep.

In central sleep apnea (CSA), what distinguishes apnea events from OSA events?

Answer: Absence of respiratory effort during apnea

The key distinction between central sleep apnea (CSA) and obstructive sleep apnea (OSA) lies in the presence or absence of respiratory effort. In CSA, the brain temporarily fails to send signals to the muscles that control breathing, resulting in a cessation of both airflow and respiratory effort. Conversely, in OSA, there is continued respiratory effort against an obstructed airway.

Which polysomnographic finding is diagnostic for REM Sleep Behavior Disorder (RBD)?

Answer: Elevated EMG tone during REM sleep

REM Sleep Behavior Disorder (RBD) is characterized by the loss of normal muscle atonia during REM sleep, leading to dream enactment behaviors. Polysomnography (PSG) confirms RBD by showing elevated or sustained submental EMG (electromyogram) tone, or excessive phasic EMG activity, during REM sleep, often accompanied by complex motor behaviors captured by video. This abnormal muscle activity during REM sleep is the diagnostic hallmark.

What is the hallmark symptom of idiopathic hypersomnia?

Answer: Non-refreshing naps lasting >1 hour

Idiopathic hypersomnia is a chronic neurological disorder characterized by excessive daytime sleepiness despite adequate nighttime sleep. A hallmark symptom is the occurrence of long, unrefreshing naps that often last for an hour or more, and patients typically wake up feeling groggy or unrefreshed. Unlike narcolepsy, it usually lacks cataplexy and other REM-related phenomena.

Which condition is associated with the 'paradoxical insomnia' complaint of severe sleep deprivation despite normal PSG findings?

Answer: Sleep State Misperception

Sleep State Misperception (SSM), also known as paradoxical insomnia, is a condition where individuals consistently underestimate their total sleep time and overestimate their sleep latency, despite objective polysomnographic findings showing normal sleep duration and quality. Patients genuinely believe they are getting very little sleep, even when sleep studies indicate otherwise. This discrepancy between subjective complaint and objective data is the defining characteristic.

What is the primary risk factor for developing shift work sleep disorder?

Answer: Irregular sleep-wake cycles conflicting with circadian timing

Shift Work Sleep Disorder (SWSD) is primarily caused by a misalignment between an individual's internal circadian rhythm and their work schedule, which often involves working during the body's natural sleep time or sleeping during the body's natural wake time. This conflict leads to symptoms like insomnia when trying to sleep and excessive sleepiness when awake, significantly impacting health and performance.

Which sleep disorder involves recurrent episodes of binge eating and drinking during partial arousals from sleep?

Answer: Sleep-Related Eating Disorder (SRED)

Sleep-Related Eating Disorder (SRED) is a parasomnia characterized by recurrent episodes of eating and drinking during partial arousals from sleep, often without full consciousness or memory of the events upon waking. Individuals may consume unusual foods, large quantities, or engage in potentially dangerous food preparation while asleep. It is distinct from nocturnal bulimia, which involves conscious binge eating at night.