Summary about Disease
Non-24-Hour Sleep-Wake Disorder (N24HSWD), also known as free-running sleep disorder, is a chronic circadian rhythm disorder primarily affecting individuals who are totally blind. It occurs when a person's internal body clock fails to synchronize to the 24-hour day, leading to a sleep-wake cycle that drifts later each day. This results in insomnia and excessive daytime sleepiness as the misalignment between the internal clock and the external environment worsens. While most commonly seen in totally blind individuals, it can rarely occur in sighted people as well.
Symptoms
Progressively delayed sleep onset and wake times
Insomnia (difficulty falling asleep or staying asleep)
Excessive daytime sleepiness
Difficulty concentrating
Impaired social and occupational functioning
Symptoms that fluctuate in severity, with periods of better and worse sleep
Causes
Lack of Light Perception: In most cases, N24HSWD occurs in totally blind individuals because light is the primary cue for entraining the circadian rhythm to the 24-hour day. Without light input to the suprachiasmatic nucleus (SCN) in the brain, the body clock drifts.
Other Factors: Rarely, N24HSWD can occur in sighted individuals, potentially due to underlying neurological conditions, genetic predispositions, or other factors affecting the circadian rhythm.
Medicine Used
Tasimelteon (Hetlioz): A melatonin receptor agonist specifically approved for the treatment of N24HSWD. It helps to synchronize the circadian rhythm to the 24-hour day.
Melatonin: Exogenous melatonin supplements may sometimes be used, although their efficacy is more variable than tasimelteon. The timing of administration is critical.
Is Communicable
No, Non-24-Hour Sleep-Wake Disorder is not communicable. It is not an infectious disease and cannot be spread from person to person. It is a disorder of the internal biological clock.
Precautions
Good Sleep Hygiene: Maintain a regular sleep schedule when possible (even though difficult), create a relaxing bedtime routine, and ensure a comfortable sleep environment.
Consistent Daily Routine: Sticking to a consistent schedule for meals, exercise, and other activities can help to regulate the circadian rhythm as much as possible.
Avoid Caffeine and Alcohol: Limit caffeine and alcohol consumption, especially close to bedtime.
Regular Consultation with a Specialist: Work closely with a sleep specialist or healthcare provider to manage the disorder and adjust treatment as needed.
How long does an outbreak last?
N24HSWD is a chronic condition, not an "outbreak." It is a persistent, ongoing disorder of the circadian rhythm. There is no defined "outbreak" duration. Symptoms will continue until effectively managed with medications or other interventions. Without treatment, the sleep-wake cycle will continue to drift.
How is it diagnosed?
Sleep History: A detailed sleep history, including sleep logs or diaries, is essential to document the pattern of delayed sleep onset and wake times.
Actigraphy: A wrist-worn device that monitors sleep-wake activity over several weeks.
Polysomnography (Sleep Study): May be used to rule out other sleep disorders.
Circadian Rhythm Markers: Measurement of melatonin and/or cortisol levels at regular intervals over a 24-hour period can help to determine the timing of the internal biological clock.
Diagnostic Criteria: The diagnosis is based on the International Classification of Sleep Disorders (ICSD) criteria, which include the characteristic pattern of delayed sleep onset and wake times, resulting in significant distress or impairment.
Timeline of Symptoms
The progression of symptoms typically involves a gradual, ongoing shift in sleep-wake timing:
Initial Phase: Noticeable delays in sleep onset times (e.g., falling asleep later and later each night).
Progressive Delay: The sleep-wake cycle continues to drift, with sleep onset times moving later by one to two hours each day.
Fluctuating Severity: Periods of relative alignment with the 24-hour day may alternate with periods of severe misalignment.
Chronic Impairment: Over time, the chronic sleep deprivation and misalignment can lead to significant daytime sleepiness, difficulty concentrating, and impaired social and occupational functioning.
Important Considerations
Impact on Daily Life: N24HSWD can significantly impact a person's quality of life, affecting their ability to work, attend school, and maintain social relationships.
Misdiagnosis: It is often misdiagnosed as insomnia or other sleep disorders, leading to inappropriate treatment.
Individualized Treatment: Treatment needs to be individualized based on the severity of symptoms, the presence of other medical conditions, and individual preferences.
Long-Term Management: N24HSWD is typically a chronic condition requiring long-term management.
Importance of Specialist Care: Consulting with a sleep specialist who is familiar with circadian rhythm disorders is crucial for accurate diagnosis and effective treatment.