Overview
Non-24-hour sleep-wake syndrome (also called Non-24, N24, or free-running disorder) is a rare circadian rhythm disorder where the body's internal clock does not align with the standard 24-hour day. In most people, the brain resets its internal clock every day using light signals, keeping sleep and wake times stable. In people with Non-24, this reset process does not work properly, so the sleep-wake cycle gradually drifts later and later — sometimes by 30 minutes to an hour each day. Over time, this means a person may be awake at night and asleep during the day, cycling through all hours of the day and night over the course of weeks. The most common cause of Non-24 is total blindness, because light cannot reach the brain to reset the clock. However, some sighted people also develop this condition, often for reasons that are not fully understood. Key symptoms include an inability to fall asleep or wake up at normal times, extreme daytime sleepiness, difficulty functioning at work or school, and mood problems like depression and anxiety. Treatment focuses on resetting or stabilizing the body clock. The only FDA-approved medication for Non-24 in blind individuals is tasimelteon (brand name Hetlioz), a melatonin receptor agonist. Melatonin supplements and light therapy may also help some patients, particularly those who are sighted. While the condition is not life-threatening, it can seriously disrupt daily life, relationships, and mental health.
Also known as:
Key symptoms:
Inability to fall asleep or wake up at consistent timesSleep and wake times that gradually shift later each dayExtreme daytime sleepiness during certain periodsDifficulty staying awake at work, school, or social eventsPeriods of insomnia alternating with periods of excessive sleepDifficulty concentrating or thinking clearlyDepression or low moodAnxiety, especially around sleepSocial isolation due to unpredictable sleep schedulesDifficulty maintaining employment or attending school regularlyHeadaches or physical fatigueFeeling 'out of sync' with the rest of the world
Clinical phenotype terms (5)— hover any for plain English
Sporadic
Usually appears on its own, not inherited from a parent
Variable
Can begin at different ages, from infancy through adulthood
Treatments
1 availableHETLIOZ
HETLIOZ capsules are indicated for the treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) in adults
Clinical Trials
View all trials with filters →No actively recruiting trials found for Non-24-hour sleep-wake syndrome at this time.
New trials open frequently. Follow this disease to get notified.
Specialists
View all specialists →No specialists are currently listed for Non-24-hour sleep-wake syndrome.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Financial Resources
1 resourcesTravel Grants
No travel grants are currently matched to Non-24-hour sleep-wake syndrome.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.How do I confirm that I have Non-24 and not another sleep disorder?,Am I a candidate for tasimelteon, and what are the risks and benefits?,What is the best time for me to take melatonin or other treatments?,How long will it take to see improvement with treatment?,What should I do if my sleep schedule keeps drifting despite treatment?,Are there workplace or school accommodations I should apply for?,Should I see a mental health professional alongside a sleep specialist?
Common questions about Non-24-hour sleep-wake syndrome
What is Non-24-hour sleep-wake syndrome?
Non-24-hour sleep-wake syndrome (also called Non-24, N24, or free-running disorder) is a rare circadian rhythm disorder where the body's internal clock does not align with the standard 24-hour day. In most people, the brain resets its internal clock every day using light signals, keeping sleep and wake times stable. In people with Non-24, this reset process does not work properly, so the sleep-wake cycle gradually drifts later and later — sometimes by 30 minutes to an hour each day. Over time, this means a person may be awake at night and asleep during the day, cycling through all hours of the
How is Non-24-hour sleep-wake syndrome inherited?
Non-24-hour sleep-wake syndrome follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
What treatment and support options exist for Non-24-hour sleep-wake syndrome?
1 patient support program are currently tracked on UniteRare for Non-24-hour sleep-wake syndrome. See the treatments and support programs sections for copay assistance, eligibility, and contact details.