Non-24-Hour Sleep-Wake Disorder Case Study
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Questions and Answers

What is the role of casein kinase 1 delta in circadian rhythm?

  • Regulates the pace of the mammalian circadian clock (correct)
  • Inhibits the function of cryptochrome
  • Disrupts the binding of clock repressor proteins
  • Promotes the expression of light-responsive genes

    • Melatonin receptor agonists are not used in regulating circadian rhythm sleep disorders.

    False

    What does the Period3 gene polymorphism affect?

    Light modulation of human sleep

    Which treatment option is commonly associated with adjusting circadian rhythms?

    <p>Melatonin receptor agonists</p> Signup and view all the answers

    Light therapy is ineffective in treating circadian rhythm sleep disorders.

    <p>False</p> Signup and view all the answers

    The histone methyltransferase ______ contributes to genome-scale circadian transcription.

    <p>MLL3</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Circadian Rhythm = Biological processes that cycle approximately every 24 hours Light Therapy = Treatment using exposure to light to help regulate sleep Melatonin = A hormone that regulates sleep-wake cycles Clock Genes = Genes that control the circadian rhythms by responding to environmental cues</p> Signup and view all the answers

    Name a common physiological function regulated by circadian rhythms.

    <p>Sleep-wake cycles</p> Signup and view all the answers

    Which of these is a major component involved in the feedback loop of the circadian clock?

    <p>Casein kinase 1</p> Signup and view all the answers

    _______ receptors in the body are known to be affected by light exposure and are crucial in the regulation of circadian rhythms.

    <p>Melatonin</p> Signup and view all the answers

    Match the following treatment options with their effects on circadian rhythms:

    <p>Light Therapy = Adjusts circadian timing Melatonin Agonists = Mimics natural melatonin Cognitive Behavioral Therapy = Addresses behavioral aspects of sleep Chronotherapy = Resets biological clock gradually</p> Signup and view all the answers

    Proteasomes have no effect on circadian clock functioning.

    <p>False</p> Signup and view all the answers

    What is the primary focus of multimodal therapy strategies in relation to circadian rhythms?

    <p>Combined therapies for a holistic approach</p> Signup and view all the answers

    What types of conditions can light therapy help treat?

    <p>Circadian rhythm sleep disorders</p> Signup and view all the answers

    Circadian rhythms have no influence on mental health and emotional well-being.

    <p>False</p> Signup and view all the answers

    What physiological process does melatonin primarily influence?

    <p>Sleep onset</p> Signup and view all the answers

    Which treatment option is specifically associated with the management of non-24-hour sleep-wake syndrome?

    <p>Tasimelteon</p> Signup and view all the answers

    Melatonin receptor agonists are ineffective in treating circadian rhythm disorders.

    <p>False</p> Signup and view all the answers

    Name one disorder associated with circadian rhythm disruption that can be treated with light therapy.

    <p>Delayed Sleep-Wake Phase Disorder (DSWPD)</p> Signup and view all the answers

    Tasimelteon is classified as a selective ______ receptor agonist.

    <p>melatonin</p> Signup and view all the answers

    Match the following sleep disorders with their characteristics:

    <p>Advanced Sleep-Wake Phase Disorder (ASWPD) = Sleep onset is earlier than desired Delayed Sleep-Wake Phase Disorder (DSWPD) = Sleep onset is later than desired Irregular Sleep-Wake Rhythm Disorder (ISWRD) = Inconsistent sleep-wake cycles Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD) = Circadian rhythms do not align with the 24-hour day</p> Signup and view all the answers

    Which of the following factors can affect the physiology of circadian rhythms?

    <p>All of the above</p> Signup and view all the answers

    Circadian rhythm disorders are primarily associated with physical health and have no impact on mental health.

    <p>False</p> Signup and view all the answers

    What is the focus of multimodal therapy strategies for sleep disorders?

    <p>Integrating various treatment approaches</p> Signup and view all the answers

    Study Notes

    Non-24-Hour Sleep-Wake Disorder

    • A circadian rhythm sleep disorder affecting up to 50% of completely blind individuals
    • Characterized by the inability to maintain a stable entrainment (synchronization) of a typically long circadian rhythm (tau > 24.5 hours) to the light-dark cycle (LD cycle)
    • Less common in sighted individuals
    • Pathophysiology less understood
    • Tau is the circadian rhythm period length (e.g., 25.27 hours)

    Case Study Details

    • 40-year-old sighted male developed the disorder after cancer chemotherapy (Hodgkin's lymphoma) with ABVD or AVD regimens
    • Actigraphy, melatonin profiles, and polysomnography diagnosed the condition with a free-running rhythm of tau = 25.27 hours
    • Bright light therapy (10,000 lux for 30 minutes) and melatonin administration (0.5-0.75 mg) failed to resynchronize the internal clock
    • Treatment caused headaches and did not entrain the free-running rhythm
    • Patient continued with the light therapy after discontinuing melatonin because it improved attentiveness and concentration during wakefulness.

    Human Sleep-Wake Cycle

    • Governed by two major processes:
      • Homeostatic hourglass process (process S): Increases linearly during the day
      • Circadian process (process C): Determines sleep timing in a ~24-hour rhythm, synchronized to the light-dark (LD) cycle
    • Suprachiasmatic nucleus (SCN) in the anterior hypothalamus is the master clock
    • SCN generates the circadian rhythm through cell-autonomous feedback loops of DNA transcription and translation
    • Phase length (tau) is relatively stable and genetically determined
    • Phase of the clock (timing) is reset by external stimuli (zeitgebers), the most important being the light-dark cycle
    • Misalignment between internal rhythm and LD cycle is a contributor to circadian rhythm sleep disorders (CRSD)

    Molecular Clock

    • Genetically encoded system for anticipation and adaptation to daily/seasonal variations
    • Consist of positive and negative feedback mechanisms involving DNA translation
    • Involves the transcription factors CLOCK and BMAL1 in initiating the expression of genes (PERIOD, CRYPTOCHROME)
    • These proteins inhibit the CLOCK/BMAL1 expression, creating a feedback loop, thus generating a circadian rhythm

    N24HSWD Treatment

    • Treatment aimed at resynchronizing the long (~25 hours) sleep-wake cycle with the 24-hour day
    • Bright light therapy (morning) and melatonin administration (evening) are strategies but may not always result in resynchronization
    • Multiple factors including individual differences, strength of circadian rhythm oscillation, and responsiveness to interventions influence treatment outcome

    Circadian Rhythm Sleep Disorders (CRSD)

    • Includes conditions like shift work sleep disorder, advanced sleep phase syndrome, delayed sleep phase syndrome, jet lag, and non-24-hour sleep-wake disorders (N24HSWD)
    • Characterized by misalignment between the internal clock and the external light-dark cycle

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    Non-24-Hour Sleep-Wake Disorder PDF 2016

    Description

    This quiz explores the complexities of Non-24-Hour Sleep-Wake Disorder, particularly in a case study involving a sighted male who developed the condition after chemotherapy. You'll learn about the circadian rhythm disruptions and the challenges faced with traditional treatment methods. Delve into the diagnosis techniques and treatment responses for a better understanding of this rare disorder.

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