Circadian Rhythm Disorders — MCQs
A 32-year-old man comes to the physician complaining of excessive sleepiness for the past several months. He reports falling asleep while dealing with customers and had a near accident when he fell asleep while driving. The patient reports that he occasionally hears voices while falling asleep and finds himself "temporarily frozen" and unable to move upon awakening. Which of the following is the most appropriate treatment for this patient?
The human body has rhythmic fluctuations in its function on a circadian cycle. Circadian rhythm is controlled by:
Berger waves (alpha waves) of EEG have a rhythm of how many Hz?
Which of the following structures is the primary regulator of circadian rhythms in the body?
A child presents with complaints of bed wetting. What is the first line of treatment?
In narcolepsy, the polysomnographic recording typically shows which of the following patterns?
In which of the following conditions would the cortisol level be highest?
In comparison to a normal healthy person, in the evening time, which of these will have an elevated ACTH as well as elevated Cortisol?
A patient presents with a temperature of 40°C and flushed skin. Which of the following interventions is most appropriate to lower the body temperature?
A 45-year-old man presents with a history of frequent falls. He has difficulty in looking down also. What is the most probable diagnosis -
Circadian Rhythm Disorders Indian Medical PG Practice Questions and MCQs
Question 1: A 32-year-old man comes to the physician complaining of excessive sleepiness for the past several months. He reports falling asleep while dealing with customers and had a near accident when he fell asleep while driving. The patient reports that he occasionally hears voices while falling asleep and finds himself "temporarily frozen" and unable to move upon awakening. Which of the following is the most appropriate treatment for this patient?
- A. Melatonin
- B. Modafinil (Correct Answer)
- C. Clonazepam
- D. Continuous positive airway pressure
Explanation: ***Modafinil*** - The patient's symptoms of **excessive daytime sleepiness** (EDS), **hypnagogic hallucinations** (hearing voices while falling asleep), and **sleep paralysis** are classic signs of **narcolepsy**. - **Modafinil** is a **non-amphetamine stimulant** that promotes wakefulness and is a first-line treatment for narcolepsy, improving alertness and reducing EDS. *Melatonin* - **Melatonin** is a hormone involved in regulating the **sleep-wake cycle** and is primarily used for **insomnia**, **jet lag**, or **circadian rhythm disorders**. - It is not effective for treating the hallmark symptoms of narcolepsy, such as cataplexy or excessive daytime sleepiness. *Clonazepam* - **Clonazepam** is a **benzodiazepine** that acts as a central nervous system depressant, primarily used for **anxiety disorders**, seizures, and some sleep disorders like **REM sleep behavior disorder**. - While it can help with some parasomnias, it would worsen daytime sleepiness in a patient with narcolepsy and is not a primary treatment for its core symptoms. *Continuous positive airway pressure* - **Continuous positive airway pressure (CPAP)** is the standard treatment for **obstructive sleep apnea (OSA)**, a condition characterized by recurrent upper airway collapse during sleep. - Although OSA can cause excessive daytime sleepiness, the patient's additional symptoms of hypnagogic hallucinations and sleep paralysis are not typical of OSA, making narcolepsy and its specific treatments more appropriate.
Question 2: The human body has rhythmic fluctuations in its function on a circadian cycle. Circadian rhythm is controlled by:
- A. Median eminence
- B. Suprachiasmatic nuclei (Correct Answer)
- C. Paramedian nuclei
- D. Supraoptic nuclei
Explanation: ***Suprachiasmatic nuclei*** - The **suprachiasmatic nuclei (SCN)**, located in the hypothalamus, are considered the primary **master clock** that regulates most **circadian rhythms** in the human body. - They receive light input directly from the retina, which helps to **synchronize** the internal clock with the external light-dark cycle. *Median eminence* - The median eminence is a structure at the base of the hypothalamus that serves as a **neurohemal organ**, where **hypothalamic releasing and inhibiting hormones** are secreted into the portal system to control anterior pituitary function. - It does not directly control circadian rhythm but plays a role in the **endocrine system's response** to circadian cues. *Paramedian nuclei* - The term "paramedian nuclei" can refer to various small nuclei located near the midline in different brain regions, such as the brainstem. - These nuclei are generally involved in various motor and sensory functions and do not serve as the **central pacemaker** for circadian rhythms. *Supraoptic nuclei* - The supraoptic nuclei are located in the hypothalamus and are primarily responsible for producing **vasopressin (ADH)** and **oxytocin**, which are then released from the posterior pituitary gland. - While they are important for fluid balance and social bonding, they are not directly involved in the **generation or regulation of circadian rhythms**.
Question 3: Berger waves (alpha waves) of EEG have a rhythm of how many Hz?
- A. 0-4 Hz
- B. 4-7 Hz
- C. 8-13 Hz (Correct Answer)
- D. 13-30 Hz
Explanation: ***8-13 Hz*** - **Berger waves**, also known as **alpha waves**, are defined by their frequency range of **8 to 13 Hz** in the electroencephalogram (EEG). - These waves are typically observed when a person is in a relaxed, awake state with their eyes closed. *0-4 Hz* - This frequency range corresponds to **delta waves**, which are characteristic of deep sleep and certain brain pathologies. - Delta waves are much slower and have higher amplitude compared to alpha waves. *4-7 Hz* - This frequency range is associated with **theta waves**, commonly seen during light sleep, drowsiness, and some meditative states. - Theta waves are slower than alpha waves and indicate a state of reduced alertness. *13-30 Hz* - This frequency range represents **beta waves**, which are associated with active thinking, problem-solving, and alertness with open eyes. - Beta waves are faster and typically have lower amplitude than alpha waves.
Question 4: Which of the following structures is the primary regulator of circadian rhythms in the body?
- A. Ventromedial nucleus
- B. Supraoptic nucleus
- C. Suprachiasmatic nucleus (Correct Answer)
- D. Dorsomedial nucleus
Explanation: ***Suprachiasmatic nucleus*** - The **suprachiasmatic nucleus (SCN)** is the primary **circadian pacemaker** in mammals, regulating various daily rhythms including the sleep-wake cycle, hormone secretion, and body temperature. - It receives direct input from the retina about light exposure, allowing it to synchronize the body's internal clock with the external light-dark cycle. *Ventromedial nucleus* - The **ventromedial nucleus (VMN)** of the hypothalamus is primarily involved in regulating **satiety** and is often referred to as the "satiety center." - Damage to the VMN can lead to **hyperphagia** (overeating) and obesity, rather than disturbances in daily rhythms. *Supraoptic nucleus* - The **supraoptic nucleus (SON)**, along with the paraventricular nucleus, is responsible for producing **vasopressin (ADH)** and **oxytocin**. - These hormones are then transported to the posterior pituitary for release, influencing water balance and social bonding, respectively, not daily rhythms. *Dorsomedial nucleus* - The **dorsomedial nucleus (DMN)** of the hypothalamus is involved in various functions including **feeding, drinking, and activity levels**. - While it can influence aspects of activity, it is not the primary regulator of the **circadian rhythm** itself; it receives input from the SCN.
Question 5: A child presents with complaints of bed wetting. What is the first line of treatment?
- A. Bed alarm technique (Correct Answer)
- B. Motivational therapy
- C. Oxybutynin
- D. Desmopressin
Explanation: ***Bed alarm technique*** - The **bed alarm technique** is considered the most effective first-line treatment for **nocturnal enuresis** in children. - It works through **classical conditioning**, training the child to wake up in response to bladder fullness. *Motivational therapy* - **Motivational therapy** can be a useful adjunct to other treatments, but it is not typically the sole **first-line therapy** due to varying effectiveness. - It focuses on building the child's confidence and encouraging dryness but does not directly address the physiological aspects of bedwetting. *Oxybutynin* - **Oxybutynin** is an anticholinergic medication that can reduce bladder contractions and increase bladder capacity. - It is usually reserved for cases where **bedwetting alarms** and **desmopressin** have been ineffective, or when there is an identifiable **overactive bladder component**. *Desmopressin* - **Desmopressin** is an antidiuretic hormone analogue that reduces urine production during the night. - While effective, it is often considered a **second-line treatment** after behavioral interventions like the bed alarm, or when rapid but temporary improvement is desired.
Question 6: In narcolepsy, the polysomnographic recording typically shows which of the following patterns?
- A. REM intrusion during inappropriate periods (Correct Answer)
- B. An absence of REM sleep in midcycle
- C. Extreme muscular relaxation
- D. Spike-and-wave EEG recording
Explanation: ***REM intrusion during inappropriate periods*** - In narcolepsy, the hallmark polysomnographic finding is **sleep-onset REM periods (SOREMPs)** - the occurrence of REM sleep within 15 minutes of sleep onset. - The **Multiple Sleep Latency Test (MSLT)** in narcolepsy typically shows **≥2 SOREMPs** along with a mean sleep latency of ≤8 minutes. - Clinically, this **REM sleep intrusion** manifests as **sudden, irresistible sleep attacks** during the day, **cataplexy** (sudden muscle weakness triggered by strong emotions), **sleep paralysis**, and **hypnagogic/hypnopompic hallucinations**. - These represent features of REM sleep (muscle atonia, dreams) occurring at inappropriate times. *An absence of REM sleep in midcycle* - This statement is incorrect as narcolepsy is characterized by an **abnormal presence and early onset of REM sleep**, not its absence. - Individuals with narcolepsy enter REM sleep much faster than normal (often within minutes rather than the typical 90 minutes). *Extreme muscular relaxation* - While **cataplexy** (present in Type 1 narcolepsy) involves sudden loss of muscle tone due to REM-related atonia during wakefulness, this is a clinical symptom rather than a continuous polysomnographic finding. - Polysomnography focuses on **sleep architecture** and the timing of **REM sleep onset**, not general muscle relaxation patterns. *Spike-and-wave EEG recording* - **Spike-and-wave patterns** on EEG are characteristic of **absence seizures** (a form of epilepsy), not narcolepsy. - Narcolepsy is a primary **sleep disorder** with distinct polysomnographic features related to **REM sleep dysregulation**, not epileptiform activity.
Question 7: In which of the following conditions would the cortisol level be highest?
- A. Normal person after receiving dexamethasone
- B. Normal person in the late evening
- C. Addison's disease
- D. Normal person in the early morning (Correct Answer)
Explanation: ***Normal person in the early morning*** - Cortisol secretion follows a **circadian rhythm**, with levels naturally peaking in the early morning (typically between 6-8 AM) to prepare the body for the day's activities. - This **diurnal variation** is a key physiological characteristic of cortisol, regulated by the **hypothalamic-pituitary-adrenal (HPA) axis**. *Normal person after receiving dexamethasone* - **Dexamethasone** is a potent synthetic glucocorticoid that **suppresses ACTH secretion** via negative feedback, leading to a significant **reduction in endogenous cortisol production**. - This is the principle behind the **dexamethasone suppression test**, used to diagnose Cushing's syndrome (failure of suppression). *Normal person in the late evening* - Cortisol levels are typically at their **lowest point** in the late evening (around midnight to early morning hours) as part of the normal **circadian rhythm**. - This nadir reflects the body's decreased need for metabolic and stress response hormones during rest. *Addison's disease* - **Addison's disease** is characterized by **primary adrenal insufficiency**, meaning the adrenal glands are unable to produce sufficient amounts of cortisol. - Patients with Addison's disease have **chronically low cortisol levels** due to glandular damage, often accompanied by high ACTH levels.
Question 8: In comparison to a normal healthy person, in the evening time, which of these will have an elevated ACTH as well as elevated Cortisol?
- A. Addison's disease
- B. Cushing's disease (Correct Answer)
- C. Transient state after exercise (evening time)
- D. Normal healthy person (evening time)
Explanation: **_Cushing's disease_** * In **Cushing's disease**, there is an **ACTH-producing pituitary adenoma** that leads to excessive ACTH secretion, which in turn stimulates the adrenal glands to produce high levels of cortisol. * This results in **chronically elevated cortisol levels** throughout the day, including the evening, and an inappropriately elevated ACTH due to increased production from the pituitary. *Addison's disease* * **Addison's disease** is characterized by **primary adrenal insufficiency**, meaning the adrenal glands cannot produce sufficient cortisol despite adequate ACTH stimulation. * While ACTH would be significantly **elevated** due to a lack of negative feedback from cortisol, the **cortisol levels would be low** or normal in response to the adrenal gland dysfunction. *Transient state after exercise (evening time)* * During and immediately after **intense exercise**, both ACTH and cortisol levels can transiently increase as part of the body's stress response. * However, these elevations are typically **transient** and would not represent a sustained, pathologically elevated state in the evening in the same way as Cushing's disease, and levels would usually normalize relatively quickly. *Normal healthy person (evening time)* * In a normal healthy person, ACTH and cortisol levels exhibit a **diurnal rhythm**, with the highest levels in the morning and the lowest levels in the late evening/night. * Therefore, in the evening, both **ACTH and cortisol levels would naturally be low** as part of the physiological circadian rhythm, not elevated.
Question 9: A patient presents with a temperature of 40°C and flushed skin. Which of the following interventions is most appropriate to lower the body temperature?
- A. Applying a heating blanket
- B. Increasing room temperature
- C. Providing warm fluids
- D. Administering antipyretics (Correct Answer)
Explanation: ***Administering antipyretics*** - **Antipyretics** such as acetaminophen or ibuprofen directly act on the **hypothalamus** to reset the body's thermoregulatory set point, promoting heat loss and reducing fever [1]. - They are the most appropriate first-line intervention for **febrile patients** with a high temperature, as they address the underlying mechanism of fever [3]. *Applying a heating blanket* - This intervention would **increase** the patient's body temperature, which is the opposite of the desired effect for a patient with a fever of 40°C. - **Heating blankets** are used for hypothermia, not hyperthermia. *Increasing room temperature* - Raising the room temperature would make it harder for the patient's body to dissipate heat, potentially leading to a **further increase** in body temperature [1]. - A cooler environment promotes heat loss through **convection** and **radiation** [1], [4]. *Providing warm fluids* - While hydration is important, providing **warm fluids** would add heat to the patient's body, which is counterproductive in this situation [2]. - **Cool or room-temperature fluids** are generally preferred for hydration during fever to avoid contributing to the elevated body temperature [2].
Question 10: A 45-year-old man presents with a history of frequent falls. He has difficulty in looking down also. What is the most probable diagnosis -
- A. Alzheimer's disease
- B. Normal pressure hydro-cephalus
- C. Parkinson's disease
- D. Progressive supranuclear palsy (Correct Answer)
Explanation: ***Progressive supranuclear palsy*** - The combination of **frequent falls** and **difficulty looking down** (supranuclear ophthalmoplegia, especially affecting vertical gaze) is a classic presentation of progressive supranuclear palsy (PSP). - PSP is a **tauopathy** characterized by **postural instability**, early falls, and distinctive ocular motor dysfunction. *Alzheimer's disease* - Primarily presents with **progressive memory loss** and cognitive decline, not typically early or prominent falls or vertical gaze palsy. - While falls can occur in later stages, they are not usually an initial hallmark symptom associated with restricted eye movements. *Normal pressure hydrocephalus* - Characterized by the triad of **gait disturbance** (often described as magnetic gait), **urinary incontinence**, and **dementia** [2]. - While gait disturbance can lead to falls, the specific difficulty in looking down is not a feature of NPH. *Parkinson's disease* - Characterized by **bradykinesia**, **rigidity**, **tremor**, and **postural instability** leading to falls later in the disease [1]. - However, difficulty looking down (vertical gaze palsy) is not a typical feature of Parkinson's disease, and falls tend to occur later in the disease course compared to PSP.
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