Non-24-Hour Sleep Wake Disorder
Non-24-Hour Sleep-Wake Disorder in Children
Does your child have total blindness and difficulties sleeping at night? Do they have trouble staying awake during the day? Are they always sleepy during the day? If you answered yes to these questions, your child might have a circadian rhythm disorder called Non-24-Hour Sleep-Wake Disorder (Non-24).
What Is Non-24?
Though Non-24 may appear to be a sleep disorder, it isn’t. It’s actually a serious, chronic circadian rhythm disorder very common in people who are totally blind, and it can arise at any age (1). Currently, there are 1.3 million people who are legally blind in the United States. Of the legally blind, 130,000 have no light perception, and as many as 70 percent suffer from Non-24 (1-3).
Difficulty at Night and Challenges During the Day
Non-24 brings about two significant symptoms. First is a profound inability to sleep or to stay asleep at night, and the second is an overwhelming urge to sleep during the day. Some nights are sleepless, and during the daytime, individuals may feel very sleepy and need to nap, yet other times are normal. The nights of poor sleep and days of excessive sleepiness happen when the master body clock is out of synchrony with the typical day-night cycle. And when this happens, it may make it difficult to focus on tasks and may affect the way sufferers interact with family, friends, and colleagues (1).
Non-24 occurs when the master body clock runs on its own natural rhythm. Hence the name, Non-24, which indicates a master body clock that is not 24-hours long. For unknown reasons, most people’s body clock runs a little longer than 24 hours, which means most people could have Non-24-like characteristics to some degree. The difference is that for sighted people, environmental light-dark cycles signal the brain to reset the master body clock every day to 24 hours.
For people who are totally blind, there are no such light cues. The body clock is left to run its natural course with extra minutes adding up day by day until their circadian rhythms are essentially upside down from a typical 24-hour day. Then, your cycle continues to shift until it’s back in sync with the typical 24-hour day and then begins to move back out of sync. That’s why people who suffer from Non-24 have some nights that are sleepless and days where they may feel very sleepy and need to nap, yet at other times their sleep pattern is normal.
A few of the key symptoms of Non-24 are
- trouble falling asleep or staying asleep,
- waking up groggy or not feeling as if you’ve gotten enough rest,
- an overwhelming urge to nap during the day or falling asleep unexpectedly,
- difficulties in managing school or work, and
- problems with concentration.
Non-24 in Children Who Are Totally Blind
Age of onset of Non-24 coincides with or follows shortly after the total loss of light perception or loss or surgical removal of the eyes (1). Eye disorders that damage the ganglion cell layer (e.g. retinopathy of prematurity), affect the optic nerve, or result in the loss of an eye entirely (e.g. retinoblastoma) are more likely to result in total blindness, prevent circadian entrainment (synchrony), and increase the likelihood of Non-24. Therefore, it is believed that Non-24 is present in children with total blindness of all ages. There are few examples, however, of Non-24 diagnoses or treatment in blind but otherwise developmentally normal children.
The spectrum of clinical manifestations of Non-24 is expected to be similar in adults and children, although in preschool children, the lack of external/social schedules can make the impact of the condition less apparent. Children and adolescents may also have behavioral problems when their circadian phases are misaligned with the social day as a result of the sleep-wake cycle disruption, and it is likely that the child’s nighttime sleep problems would negatively impact the sleep of family members.
Currently, children with Non-24 are left untreated or treated inappropriately. Sleep-promoting agents are usually the first to be tried, as the disorder is frequently misdiagnosed as chronic insomnia or even depression. Sedative/hypnotic medication may cause confusion at night, rebound awakening later in the night, or hangover effects during the day (4). These sleep-promoting agents are ineffective in this condition and can result in additional sleep disruption. Sedative/hypnotics may put the person to sleep at night but do not prevent him or her from still feeling sleepy during the day when out-of-phase because of the internal circadian drive to sleep.
Frequently Asked Questions About Non-24
Can Non-24 Correct Itself?
Non-24 does not permanently correct itself. For people with Non-24, the sleep-wake cycle continually shifts until it realigns with the 24-hour day. The speed of a person’s body clock determines how long they will be in alignment with the 24-hour day before shifting back out of alignment.
How Is Non-24 Diagnosed?
Diagnosis of Non-24 is primarily based on a person’s history of sleep and wakefulness complaints. This is typically recorded in a sleep diary to show the irregular intervals of sleep and wake periods within a 24-hour period (5).
If you or someone you know experiences any of the symptoms associated with Non-24, speak with a healthcare professional.
What Are the Treatment Options for a Child with Non-24?
Currently, no FDA-approved therapies exist to treat Non-24 in children or adolescents. Anecdotally, individuals with Non-24 report that receiving a proper diagnosis is beneficial to their well-being. Following a rigid structure, particularly with regard to daytime and bedtime rituals, may provide some limited relief but will not treat the underlying problem. Even with additional structure, good sleep hygiene practices and sleep training methods such as Ferber’s, the child’s internal clock will cycle through phases in which they will be out of sync with the environment leading to sleep disturbances.
How You Can Help Non-24 Research Scientists
New research studies may lead to better understanding of Non-24 in children who are totally blind, and researchers are eager to better understand Non-24 and circadian rhythm problems in children who are totally blind. To that end, clinical studies will be conducted specifically in children and adolescents to determine whether a certain oral compound is safe and effective in treating Non-24 in the pediatric population.
Why Is It Important to Participate?
Joining the Patient Registry for Blind Subjects with Sleep-Related Problems will help researchers better understand sleep-related problems in people who are blind, including investigation of potential therapeutics. The registry will help researchers identify and recruit patients who are eligible for participation in future clinical studies and to provide a forum for raising awareness about Non-24. Participants will have the chance to take part in a survey. The survey consists of questions regarding the degree of vision impairment and sleep problems that individuals may be experiencing. Patients enrolled in the registry will also have the option of receiving notification of upcoming research projects for which they may be eligible.
The Non-24 Share More Campaign
Sign up for the Non-24 patient registry to participate in clinical trials while creating support for the blindness community. For each completed survey, a donation of $24 will be made to organizations that support people with blindness.
Your help is needed in advancing the understanding of Non-24, particularly in children. Call toll-free at 1-844-361-2424 or visit Non-24 for more information or to participate in the registry.
- Lockley SW, Arendt J, Skene DJ. (2007). Visual impairment and circadian rhythm disorders. Dialogues Clin Neurosci., 9(3):301-14.
- National Advisory Eye Council. Vision Research: A National Plan. 1-27. 2003. National Institutes of Health. Ref Type Report.
- Sack, R. L., Lewy, A. J., Blood, M. L., Keith, L. D. & Nakagawa, H. (1992). Circadian rhythm abnormalities in totally blind people: incidence and clinical significance. J. Clin. Endocrinal. Metab 75, 127-134.
- Stores, G. (1999). Recognition and management of narcolepsy. Arch Dis Child 81: 519-524.
- Sack RL, Auckley D, Auger RR, Carskadon MA, Wright Jr KP, Vitiello MV, Zhdanova IV. (2007) Circadian Rhythm Sleep Disorders: Part II, Advanced Sleep Phase Disorder, Delayed Sleep Phase Disorder, Free-Running Disorder, and Irregular Sleep-Wake Rhythm. Sleep. 30(11):1484-1501.