What Challenges Do People With Non-24-Hour Sleep-Wake Disorder Face? Update 04/2024

Those who suffer from non-24-hour sleep-wake disorder (N24SWD) have an abnormal circadian rhythm that deviates from the standard 24-hour pattern. Bedtimes tend to get later and later for sufferers of N24SWD, resulting in disrupted daily routines.

It’s comforting to know that you’re not the only one with a non-24-hour sleep-wake issue. The medical community and the general public are becoming more aware of circadian rhythm disturbances.

What Challenges Do People With Non-24-Hour Sleep-Wake Disorder Face?

People with non-24-hour sleep-wake disorder typically have difficulty keeping up with their academic, professional, social, and other responsibilities as a result of their irregular sleep patterns. Making appointments with doctors, going shopping during regular business hours, or taking public transportation late at night may be problematic for them as well.

Because N24SWD is so uncommon, the general public isn’t aware of it. Since many persons with N24SWD experience judgment from those who don’t understand the difficulties of the disorder, this can be a problem for those with the disorder. They may be viewed as lazy, sluggish or not trying hard enough to sleep at typical times by people with N24SWD.

Many persons with N24SWD are unable to sleep at a time that is in accordance with their natural circadian cycle because of this pressure. As a result, people may be misdiagnosed with sleep disorders like insomnia or experience daytime exhaustion as a result of this. Sleep deprivation at night is common in those with N24SWD due to their tendency to depend on naps to get them through the day. Chronic circadian misalignment and sleep deprivation are real risks for those with N24SWD who aren’t properly diagnosed and treated.

Studies on shift workers have indicated that circadian misalignment puts them at risk for attention, memory, and mood issues in the short term. Increased danger of workplace and academic accidents is caused by this. Sleep deprivation can lead to obesity, diabetes, cardiovascular disease, depression, anxiety, and a host of other chronic problems in the long run.

Talking to Your Doctor About Non-24-Hour Sleep-Wake Disorder

Preparing for your doctor’s appointment ahead of time will help you have a productive discussion about your sleep-wake issue. You may find it helpful to record your sleep and wake schedules for a few months as part of this preparation. Keep an eye out for other signs, such as:

  • Tiredness that persists throughout the workday.
  • The inability to fall asleep.
  • Not feeling rested despite having slept through the night.
  • Anxiety or despair, to put it mildly.
  • Memory and attention issues.

Your doctor will likely prescribe melatonin, bright light therapy, or a combination of the two based on more inquiries about your sleep habits and tests to monitor your circadian rhythm. A regular sleep hygiene routine can help reinforce circadian cues and help manage non-24-hour sleep-wake disorder.3 Here are a few pointers:

  • Cool, dark, and peaceful in the bedroom.
  • Assembling a sleep ritual that includes calming activities.
  • Caffeine should only be used sparingly.
  • Maintaining a healthy diet and drinking enough of water throughout the day.
  • ensuring that you’re getting enough exercise.
  • It’s best to avoid screen time at night or use a blue-light filter.

You should always follow your doctor’s treatment recommendations, but you should also let them know if anything doesn’t seem to be working for you so that they can make any required adjustments. A sleep specialist with more expertise in circadian rhythm issues may be able to assist you.

Talking to Friends and Family About Non-24-Hour Sleep-Wake Disorder

Friends and relatives may be able to understand why you appear weary or disinterested or are occasionally unable to meet commitments if you explain your non-24-hour sleep-wake condition to them.

Explain how N24SWD5 has affected your life, including how you’ve fallen asleep at unsuitable times or become irritable because of sleep deprivation. For those unfamiliar with the term “non-24-hour sleep-wake disorder,” try relating it to something they are more familiar with, like jet lag. You can also direct them to resources for further information.

Online support groups and organisations can be a source of validation for many people. If you’re struggling with non-24-sleep-wake hour disorder, talking to others who are going through the same thing can make you feel less alone and provide you new coping strategies.

How To Maintain a Social Life With Non-24-Hour Sleep-Wake Disorder

N24SWD can make it challenging to have a healthy social life. However, there are a few things you can do to make the process a little less stressful..

If possible, offer activities that people may participate in at any time of day or night, such as taking a stroll.

Schedule events during weeks when you know you’ll be able to get a good night’s sleep. For shift workers and freelancers, making connections with others in the same circumstances can open up more schedule options.

Although some of these choices may not be appropriate if you are on a tight 24-hour therapy regimen, there are many more ways to keep in touch with pals. It’s possible to go out for the night at a bar or nightclub, but the late-night noise and alcohol intake could make it even more difficult to sleep afterwards. To answer messages from friends or to talk with friends in other time zones, you can use social media at any time of day or night, although using screens at night can interfere with sleep.

Regardless of which strategy you use, it is important to keep your therapy in mind. Be careful not to increase or acquire behaviors that will have a detrimental impact on your N24SWD treatment.

Non-24-Hour Sleep-Wake Disorder in the Workplace

This condition is considered a handicap under the American Disabilities Act (ADA) since it severely restricts the capacity to concentrate, interact with people, and work. The Americans with Disabilities Act (ADA) requires most businesses to make reasonable accommodations for you if you are qualified for the job in question.

As part of the American Disabilities Act, companies are not obligated to accommodate employees with disabilities if doing so would cause them a “undue hardship.” A lawyer may be necessary for you depending on your profession. Your business may be able to provide you with a choice of options, including working part- or full-time hours, or working from home.

Be sure to bring up the ADA when you speak with your employer, and be specific about how N24SWD affects your ability to do your job, as well as any workarounds. Consult a lawyer if necessary. You may also choose to tell your coworkers about the specifics of your case if you believe it will assist build a stronger team.

Career Ideas for People With Non-24-Hour Sleep-Wake Disorder

When it comes to certain jobs, those with erratic sleep habits have an advantage. Regardless of your N24SWD, you may find yourself gravitating toward employment that offer more flexibility in your working hours. The following are some examples of jobs that can be done from home:

  • Freelance writer
  • Translator
  • Web developer
  • Graphic designer
  • Massage therapist
  • Personal trainer
  • Delivery worker
  • Photographer

If you are unable to maintain a 24-hour cycle or if you still feel unwell even after adhering to a typical “day and night” pattern, these jobs may be of interest.

Students With Non-24-Hour Sleep-Wake Disorder

This right applies to students with disabilities in all educational settings, including secondary and postsecondary institutions, as set forth in Section 504 of the 2008 Disabilities Act Amendment Act. Accepting classes online, enabling students to miss some classes and make up the work at another time, or taking a reduced course load are examples of reasonable accommodations for students.

Signs & Symptoms

N24’s most common symptoms include occasional nighttime sleeplessness and excessive daytime sleepiness, as most people are forced to keep a regular job, school, or social schedule. Because of the disorder’s cyclical nature, some people with it will feel normal for days or weeks at a time when their body’s cycle is in sync with society’s routine. An individual’s sleeplessness and excessive daytime sleepiness will return if their bodily rhythms become out of sync with those of the light-dark cycle (or night-day cycle) and their obligations.

Individuals with N24 often sleep for anything from 24.1 hours to as many as 28-30 hours a night. The frequency of cases with cycles shorter than 24 hours, in which a steadily increasing rhythm is expected, is exceedingly low.

Some people with N24 may find relief from symptoms of insomnia and exhaustion if they are permitted to sleep on their own cycle, but they may not be able to keep a schedule that is essential for social and professional obligations. Some patients with N24, on the other hand, may continue to experience exhaustion, grogginess, malaise, and sleep disturbances no matter what their schedule is, presumably because their internal circadian rhythms are still out of sync. Molecular clocks are found in practically every cell in the body, and scientists believe that the desynchronization of these clocks is the cause of these symptoms, according to recent studies.

To avoid the accumulation of chronic sleep deprivation symptoms such as excessive daytime drowsiness and exhaustion as well as depression, difficulties concentrating, and memory problems, N24 must be diagnosed and handled. The inability of someone with N24 to fulfill social and professional responsibilities can be extremely debilitating. And you’re awake when everyone else is asleep, it’s easy to feel isolated and lonely.


The 24-hour day-night cycle (light-dark) has shaped the evolution of all species on Earth. Organisms have evolved methods to time their cellular and metabolic processes in anticipation of this regular rhythms. A biological clock based on a cycle of synthesis of DNA and protein is present in nearly all cells of the human body. White blood cells and cells of the heart, brain, liver, and many other tissues have been found to have clock gene activity.

Clocks in the individual cells run on a nearly 24-hour cycle. It’s called circadian rhythm (circa-” means around and “dian” means pertaining to the day). As a result of the fact that the clocks are not perfectly accurate, the clocks of individual cells can drift apart from one another or from the Earth’s day-night cycle. There is a master clock in the brain that keeps these clocks in sync. This master clock keeps the body’s cellular clocks in sync, much like a conductor does while leading an orchestra in timed performance.

The suprachiasmatic nucleus (SCN), a region of the brain known as the hypothalamus that regulates many fundamental bodily functions, houses the master clock. An estimated 20,000 cells make up the SCN, and their firing rates are synced up in a 24-hour cycle thanks to the SCN’s intricate network. When the SCN cells fire, signals are sent to many other parts of the brain, which in turn send these clock signals to the body via neurochemical and hormonal ways. This is how the body keeps time.

The body temperature cycle and the generation of the hormone melatonin are two of the most well-known rhythms driven by the clock signal. The SCN communicates with other parts of the hypothalamus to control the body’s temperature. Body temperature fluctuates in a wave-like fashion, peaking throughout the day and dipping at night.

Melatonin is produced by the pineal gland, which is controlled by the SCN via a complicated polysynaptic pathway that travels through the cervical spinal ganglia. The hormone melatonin, dubbed “the hormone of darkness,” is secreted by the body when it is dark outside. There, the pineal gland releases melatonin into cerebrospinal fluid, from where it travels by blood to every cell in the human body. It regulates cell processes by acting on certain melatonin receptors. It also helps to maintain the body’s temperature cycle by aiding the body’s nocturnal dip. Additionally, lowering one’s body temperature aids in the preparation for sleep by lowering cortisol levels and decreasing blood flow to the brain.

However, despite its role in coordinating cell clocks across the body, the SCN must still be synchronized with the Earth’s 24-hour cycle. if left to its own devices, the SCN maintains a 24-hour rhythm. The intrinsic period of the SCN clock is around 24.2 hours in healthy individuals. It would take several days before the clock in the SCN remains “entrained” if the cycle could not be corrected to equal 24 hours.

Light-dark exposure is the major method of maintaining a correct SCN clock. SCN receives a signal from the retina, which is different from the cells utilized for vision, via a nerve path known as retinohypothalmic tract, which transmits this information to the retina. Light exposure in the early morning hours provides a signal that moves the SCN’s clock forward by an hour, allowing the body’s internal clock to be set for the day. The SCN receives a delay signal when light falls on the eyes late at night. Phase-response curves can be used to forecast the effects of light on the biological clock by plotting the influence of light at different times of day and night. Longer-term running of the SCN clock causes it to fall out of sync with the natural day-night cycle, but morning light exposure can correct this. Late night light exposure will slow down the SCN clock if it runs shorter than 24 hours. In this way, the SCN clock is synchronized with the day and night rhythms of the natural world. Circadian rhythms are stabilized in healthy people by regular exposure to morning light.

Melanopsin, a pigment found in the retina, serves as a light sensor for circadian processes in the retina. Circadian rhythms are influenced more by blue light than any other color, due to melanopsin’s sensitivity to it. Much less influence is had by using red, orange, and yellow light. Under certain conditions, the green light can also affect rhythms.

The sleep-wake cycle is one of the most critical biological rhythms regulated by the SCN. The homeostatic and circadian processes are in charge of regulating this cycle. Brain and body repair themselves throughout sleep and build up energy for the day’s activities. These resources are steadily depleted during the day, as long as the person is awake. The gradual dwindling of energy throughout the day causes a strong need to sleep in order to replenish it. The homeostatic sleep drive is the term for this phenomenon. For example, a person might wake up energised and then progressively lose that energy during the day as if they were a battery. An inconsistent daytime alertness level, with dangerously low levels of awareness in the afternoon and evening, would follow. Aside from the circadian mechanism, the SCN also regulates alertness in a balancing manner. An increase in attentiveness signals is sent to the brain and body as time passes and as energy levels drop. There are a few hours before bedtime when this vigilance signal is at its greatest. Since sleep is practically impossible in this zone of maximal alertness, it’s referred to as the “forbidden zone” for sleeping. So that you can get some rest at your usual bedtime, the SCN gradually reduces the level of awareness that it sends to the body. Before the night’s sleep has finished, the circadian awareness signal has been lowered even further to prevent early awakening.

To maintain a steady state of alertness during daylight hours, the circadian and homeostatic processes work together to maintain a 7-9-hour period of uninterrupted sleep at night, with the occasional exception of a midafternoon nap period.

When everything is running smoothly, the SCN receives light signals from the eyes, and the SCN in turn coordinates the clocks in the pineal gland and cells all over the body with the 24-hour day-night cycle. Like the instruments in a well-tuned orchestra, the clocks all run on the same 24-hour cycle. Finally, the circadian alertness signal interacts with the body’s homeostasis mechanism to create an individual who can sleep through the night and remain attentive during the day.

Many things can go wrong with this system and cause a circadian disorder like N24, but this is the most common one.
1. Blindness. N24’s most common cause is a condition that affects the blind. As a result, people who are fully blind (not able to perceive light) will not be able to adjust their biological clocks to the 24-hour day. A blind person’s internal clock can’t be reset if the SCN clock starts to wander away from 24 hours without medical treatment. Blind people’s circadian systems will gradually drift over time since the SCN’s natural rhythm is not always precisely 24 hours. For an extended period of time, they’ll alternate between times of deep sleep at night and intervals of light sleep throughout the day. However, there are also instances where a person’s sleep cycle progresses gradually and the period is shorter than 24 hours. People who have N24 typically have a circadian rhythm of 23.8 to 25 hours.

2. Changes in the sensitivity to light. Those who are sighted may be less sensitive or insensitive to light’s impact on the circadian clock. Circadian light signals are transmitted through a distinct cell pathway from the eye and brain, which may or may not be functioning properly. A blind individual’s circadian condition is exactly the same as that of a person who is completely unresponsive to light’s circadian effects. Although light may affect their cycles to some degree if they are light-sensitive, this effect may not be powerful enough to counteract circadian drift in their specific lighting environment.

Contrarily, patients with N24-related delayed sleep phase disorder were shown to be extremely light sensitive. It’s possible that their circadian cycles will be thrown off if they’re exposed to typical room light at night. N24 is the result if the delay accumulates.
3. Environment. It’s also possible that light exposure from the environment has an impact. The circadian rhythms of healthy people can often be disrupted by removing all time cues from their environment and allowing them to turn their lights on and off whenever they like. The rhythm can last up to 25 hours, which is significantly longer than the SCN’s natural 24.2-hour cycle. Self-selected late-day light exposure has a delayed effect. If you live in a situation where you’re constantly exposed to bright light, you’re more likely to develop N24. A 24-hour schedule can be maintained even in a non-isolated setting with conventional time cues for those with N24.

4. Affecting hormones. If melatonin is involved in the genesis or continuation of N24, it should be considered a possible factor. Melatonin is an important sleep aid, but some patients with N24 have lower levels of the hormone than is normal. Too much melatonin, on the other hand, could have the opposite effect. One study found that the antidepressant fluvoxamine, which elevates melatonin levels by blocking its metabolism, also caused DSPD, an illness strongly related to N24. The melatonin metabolism of some people can be aberrant, resulting in daytime levels that are higher than normal, which can lead to problems with the circadian clock.

5. Functional differences between cell phones. The cellular clock has been the subject of certain other investigations into the origins of irregular circadian rhythms. According to research done on healthy volunteers, there is a connection between the cellular clock’s period and the phase of entrainment. People who get up early have a shorter circadian cycle than those who wake up late. N24 may be an extension of excessive “eveningness,” in which the cellular rhythm may be too far away from 24 hours for typical light exposure to restore it, a circumstance described as being “beyond the range of entrainment.” N24.
There are two techniques to calculate the period of the biological clock in humans. It is possible to begin by examining the time period in which the person was living in his or her normal environment. In these circumstances, a regular person’s life span is 24 hours. No matter how much time passes, their sleep-wake cycle remains the same. By definition, someone with N24 has a period that is longer than 24 hours, and in some cases, up to 25-26 hours.

The circadian clock is influenced by external elements, particularly light, in normal circumstances. In order to find the intrinsic period of a clock, scientists use unique experimental settings (constant routines and forced desynchronization) to cancel out these external influences. Assuming no external effects were present, this is the time the clock would display. The clock’s intrinsic period is around 24.2 hours for most people. Regular subjects can maintain a 24-hour day by exposing themselves to normal light on a daily basis, which makes up for the 0.2 difference.

Experiments on the intrinsic period of N24 patients have been done three times in small studies. Six individuals in one study discovered a 24.5-hour window; four in another; and one patient in a single case report also discovered a 24.5-hour window. To maintain a 24-hour cycle, these N24 patients need an adjustment of at least 0.5 to 0.9 hours every day. This correction may not be possible with normal light exposure. This may make 24-hour entrainment impossible if it is paired with other variables that shift the clock later.

Muscle cells (fibroblasts) isolated and cultured have also been the subject of investigations looking at the internal clock. A person’s life span is associated with the length of time he or she spent in a cell culture. Clock periods are determined on a cellular level, as demonstrated by this. Thus, it is possible that certain N24 patients are experiencing an inherent period lengthening due to circadian clock biochemical dysfunction.

There are a few severe evening type persons who do not have clinical N24 who have longer intrinsic periods than the average N24 patient. Despite the fact that N24’s extended intrinsic period is definitely a crucial role in its development, there may be additional elements that make the difference between an extreme evening chronotype and free-running N24.
6. Disparities in the way sleep is regulated. The circadian and homeostatic control of sleep are two more probable causes of N24. Patients with N24, on average, require a little more sleep than the ordinary person. When necessary, this can be quite dangerous. For someone who needs 12 hours of sleep and is awake for a usual 16 hours, their day will be 28 hours long, compared to 8 hours for a healthy person. Changing the timing of light exposure will lead to a shift in the sleep cycle, which in turn will lead to an N24 cycle. To put it another way, people with sleep deficiency who require a longer day to restore their homeostasis may only get 8 hours of sleep per night, requiring a total of 20 hours of awake time.
A common symptom of N24 is an irregular phase angle between sleep and internal circadian rhythms, which is also known as the time it takes for a person to fall asleep. The circadian cycle of body temperature is used to explain the link between sleep timing and phase angle. Healthy people’s body temperatures begin to drop shortly before falling asleep and remain at their lowest levels until the last two hours of sleep when they normally awaken. For those who have N24, the period between the temperature minimum and the time of waking (sleep offset) may be anywhere from four to eight hours, depending on the severity of the condition. If an N24 has an abnormal relationship between sleep cycles and their circadian rhythms, they will sleep through the phase advance portion of their clock and miss out on the light they need to reset their clock on a daily basis because the body’s light-dark response is synched with internal rhythms (such as core temperature). Due to their temperature cycle, they are also exposed to light during the phase delay section of the phase response curve. Because of this, their circadian rhythms are pushed towards longer days. In this way, the already-extended intrinsic duration of N24 patients is amplified even further.

It’s also crucial that sleepiness is regulated by the body’s internal clock or circadian rhythm. There is a “forbidden zone for sleep” that occurs even in healthy people about an hour or two before customary bedtime and is linked to the highest levels of circadian alertness. People with N24 are unable to sleep on a 24-hour cycle because the banned zone appears too late in the day and is too powerful.

Some effects of sleep and wakefulness on alertness may reinforce this pattern of sleep and awakeness. People who have slept for a long time are typically in a state known as sleep inertia when they wake up. This grogginess and sluggishness may last for several hours in patients with N24. They get more alert the longer they remain awake. A possible explanation for this may be found in an observation that brain cell circuits grow more excitable with time spent awake. Their alertness will have peaked by the time they need to go to bed (in an attempt to maintain a 24-hour cycle), and their brief burst of energy will prevent them from falling asleep at their usual time. Because they finally feel up, attentive, and productive, people with N24 may not want to try to sleep at this time.
7. Development. Another aspect is the development of the brain’s circadian and sleep centers. N24 and other circadian rhythm and sleep problems have been found to occur rather frequently in autism and other widespread developmental disorders. Many people believe that the brain’s circadian and sleep centers are malfunctioning because of a lack of neurochemical or structural development. It’s possible that some N24s don’t have widespread developmental abnormalities, but rather sleep and circadian brain dysfunction.

8. Trauma. Damage to the brain, such as a head injury, has been linked to N24 in previously healthy people. The hypothalamus and pineal gland are thought to be damaged as a result of the head injury, as are other sleep and circadian areas in the brain. N24 has also been linked to brain cancers, according to research. Survivors of tumors on the pons and hypothalamus have been found to suffer from circadian sleep abnormalities. Craniopharyngiomas are more likely to cause sleep problems than other tumors. In some situations, the tumor itself is to blame, while in others, radiation treatment to the head is to blame. In one example, a transitory N24 was caused by an aneurysm near the SCN. According to one study, N24 has also been found during chemotherapy treatment for Hodgkin’s lymphoma.

A physical abnormality that causes total blindness, such as a genetic defect, sickness, or injury, can cause secondary N24.
9. Iatrogenic. The more frequent disease, delayed sleep phase disorder, can also lead to the development of N24 (DSPD). Chronotherapy, a common treatment for DSPD, instructs the patient to gradually delay their bedtime and wake time up to three hours a day until they reach a more socially acceptable sleep/wake schedule. An N24 schedule can be briefly used for this purpose. Unfortunately, an N24 schedule can be almost tough to break in certain patients once it has been established. One circadian rhythm disorder has been replaced by another that is considerably more debilitating, N24. Once established, the N24 pattern is difficult to break for a variety of reasons. Other factors include the timing of sleep in relation to the temperature cycle. Circadian system “plasticity” is another term for this. When an organism has been placed on a certain cycle, including a non-24-hour cycle, the circadian clock remembers and seeks to maintain the same pattern. Numerous clinicians are still unaware of the dangers associated with chronotherapy, even though it has been recognized since the 1990s.

10. Genetics. N24 appears to have a genetic component, according to accumulating data. Most of the time, it’s not a simple genetic disorder (Mendelian inheritance). In most cases, N24 patients do not have a close relative who suffers from the disease. Some hereditary variables, however, appear to predispose someone to develop N24.

SNPs (single nucleotide polymorphisms) have been detected in the gene BHLHE40 in four people with N24. Mutations in this gene, which code for components of the circadian clock, could lead to the anomalies shown in N24.

PER3 gene polymorphisms were linked to N24 in a separate analysis of 67 participants.

The circadian clock gene PER3 is also encoded by PER3. Some of the same variants were found in Non-24s who had an extreme evening chronotype, or a genetic inclination to perform better in the evening hours. Free-running period (in animals), homeostatic desire for sleep, and light sensitivity are all thought to be affected by variations in the PER3 gene (SNPs and repeat counts) (in humans). N24 has been suggested, with some evidence, to have abnormalities in all of these components.

The CRY1 gene, which is involved in the circadian clock, has been implicated in DSPD, a disorder similar to N24, in a study of a single-family.

The genetic screening of over 100,000 people in several genome-wide association studies has revealed genetic connections with human chronotypes. There was no specific research on N24 patients, but the fact that N24 is strongly associated with an extreme evening chronotype suggests that some of the same genetic variables may be at play in these investigations.

A genetic predisposition to the development of N24 has been hypothesized based on investigations of the genes involved in Non-24 as well as more general studies of circadian rhythms.

Affected Populations

It’s unclear how many people have N24, although it’s widely assumed that more blind people are infected than sighted ones.” N24 is thought to be present in between 55% and 70% of those who are completely blind. For example, people who have had their eyes enucleated are more likely to be affected than those with some degree of retinal function (for example). Approximately 100 case studies of sighted people with N24 may be found in medical journals around the world, but no one knows how common it is. Single Japanese research documented fifty-seven of these instances. One hundred and eighty-eight members of the Circadian Sleep Disorders Network (under “organizations”) have disclosed that they or a member of their family has N24. More than 500 people have joined the N24 Facebook group, but it’s not clear how many of them are patients. There may be a large number of unrecognized cases due to the condition’s relative obscurity.

There are more male sighted patients than female ones, although it’s unclear if this is typical of the entire patient body. In healthy adults, men tend to have longer circadian rhythms than women, according to research. Male and female patients make up about equal proportions in support groups. Although N24 can appear at a younger or older age, the most common onset is in the late teens or early twenties. It appears that the condition is a lifelong one. There isn’t enough evidence to say whether or not N24 is progressive. Many long-term sufferers report that symptoms intensify as they become older, along with an increase in day length, however, this may be due to the interaction between N24 and age-related sleep disturbances. As of right now, there is no clinical study on how N24 evolves across the lifespan.

In 1970, Eliott, Mills, and Waterhouse described N24 in the medical literature.

Related Disorders

N24’s symptoms can be compared to those of the following illnesses. Using comparisons can aid in determining the cause of a patient’s illness.

Although less frequent than N24, delayed sleep-wake phase disorder (DSPD) alters the body’s sleep-wake cycle so that it occurs several hours later than in healthy people.

Those with DSPD have a sleep phase delay that is rather stable from day to day, whereas those with N24 have sleep times that are continually shifting later. A person with DSPD, for example, may often retire to bed about 4 a.m. on a regular basis. When a change occurs, it’s not cumulative; it can happen at any time of day (for example, at 3 am one day and 5 am the next). For example, if you have N24, you’ll fall asleep at 4 a.m. one day, 5 a.m. the next, and so on all night long.

Even though some people with the disorder have biological clocks set to a longer than normal circadian rhythm, they nonetheless have the potential to entrain to a 24-hour day, just like those with N24. People with DSPD have a longer circadian rhythm, which causes their biological clocks to be entrained at different times. There is some evidence to support the hypothesis that the underlying biology is the same in some cases for people with N24 who have DSPD, either as a result of their disorder progressing or due to chronotherapy (see “causes”).

The absence of a well-defined circadian cycle of sleep and wakefulness is a hallmark of irregular sleep-wake rhythm disorder (ISWRD). There appears to be little or no pattern to the sleep patterns of those who suffer from this condition. Most people sleep at least three times throughout a 24-hour period. When compared to N24, ISWRD patients have a clearly established sleep rhythm, although their cycle is longer than 24 hours. Patients with ISWRD have no discernible rhythmic pattern at all. Those with long-standing N24 have been found to have increasingly disordered sleep as the disorder worsens, although they usually preserve at least some rhythmic pattern, allowing doctors to differentiate them from people with ISWRD. Developmental impairments and dementia are the two most common causes of ISWRD. Also, a brain tumor or injury to the head might cause it. Circadian rhythm sleep disorder or irregular sleep pattern are other names for ISWRD.

Apnea is an extremely prevalent kind of sleep apnea characterized by frequent, brief pauses in breathing during sleep. Snoring, impatience, a lack of attention, and/or cognitive impairment are all symptoms of the disease, as are frequent nighttime disturbances in sleep and excessive daytime sleepiness. Having a big neck, thin or packed airways, and obesity are all linked to snoring. Airway collapse is the most common cause of obstructive sleep apneic syndrome, which is the most common form of sleep apnea. A partial reawakening and subsequent gasping for air are possible outcomes. This condition can cause high blood pressure, irregular heartbeats, and an increased risk of cardiovascular diseases such as heart attack, stroke, and diabetes if it is not addressed. Because obstructive sleep apnea affects 24% of men and 9% of women, it’s not uncommon for someone with N24 to also suffer from this condition.

N24 may be mistaken for idiopathic hypersomnia, or the two conditions may coexist. Chronic, persistent hypersomnia may also cause an individual to have a sleep onset time that shifts later every day if the individual remains awake for a normal amount of time while sleeping for an abnormally prolonged duration of time. Symptoms of idiopathic hypersomnia include periods of excessive sleepiness with no apparent cause (idiopathic). Symptoms might be long-lasting or recurring. It is possible for some people with idiopathic hypersomnia to sleep for lengthy amounts of time (up to 10 hours), while others sleep for shorter periods (e.g. fewer than 10 hours). Chronic insomnia caused by an unknown ailment has the potential to derail many facets of daily life. The illness is treated with a combination of counseling and medication.

Nausea and tiredness throughout the day are symptoms of the neurological sleep condition narcolepsy, which is frequently referred to as excessive daytime sleepiness (EDS). Drowsiness episodes might last anywhere from a few seconds to a few minutes. The number of occurrences in a single day ranges from a few to several. Evening sleep patterns (also known as nocturnal sleep) can be thrown off. Cataplexy, a form of hallucination that occurs before or after sleep, and momentary paralysis upon waking up are three additional symptoms that are frequently connected with narcolepsy. It’s possible that narcolepsy is linked to “automatic conduct,” which is the ability to perform a task without thinking about it afterward. To learn more about narcolepsy, type “Narcolepsy” into the Rare Disease Database search box.

Hypersomnolence (i.e., sleeping up to 20 hours a day), excessive food intake (compulsive hyperphagia), and behavioral abnormalities, such as an excessively unconstrained sexual drive, are all hallmarks of Kleine-Levin syndrome. Affected people may be irritable, lack energy (lethargy), and/or lacking in emotions when they are awake (apathy). It’s possible that they’ll appear bewildered and have hallucinations. Kleine-Levin syndrome has recurring symptoms. Symptoms may be absent for weeks or months at a time for an affected person. Symptoms, if present, might last anywhere from a few days to a few weeks. The signs and symptoms of Kleine-Levin syndrome may fade away with time in some people. However, it is possible that relapses will occur in the future. Kleine-Levin syndrome has no recognized cause. (In the Rare Disease Database, type in “Kleine-Levin” to learn more.)

In addition, hypothyroidism, periodic limb movement disorder, depression, hypoglycemia, and other illnesses can cause excessive daytime sleepiness, as can other medications. In addition to the symptoms of disturbed sleep and wake patterns and excessive daytime sleepiness that are associated with conditions such as heart disease, diabetes, prostate disorders, congestive heart failure, and other bladder issues, conditions such as interstitial cystitis and cystoceles can also cause excessive nocturia.


The patient’s own sleep diaries, which demonstrate a sleep cycle that does not fit neatly into a 24-hour cycle, are used to make the first diagnosis. If a patient’s sleep schedule isn’t restricted by social or professional obligations, it’s easier to spot this.

An actigraph, a wrist-worn device that records movement and is used to assess sleep timing, can help confirm a diagnosis. At least a few weeks should be spent wearing an actigraph in order to allow the sleep cycle to complete a full rotation around the clock.

Even though this approach is more typically employed for research purposes, a non-24-hour pattern of melatonin secretion may be a useful confirmation of a diagnosis.

Medical Evaluation and Follow-Up

The primary tools for the initial evaluation and subsequent monitoring are sleep logs and actigraphy. The use of polysomnography (an overnight sleep study) isn’t required for the diagnosis of N24, but it can be helpful in ruling out other possible illnesses. There must be a time in the patient’s cycle during which polysomnography may be performed for it to be of any utility.


Hetlioz (tasimelteon), a melatonin receptor agonist, was authorized by the FDA in 2014 to treat N24. The first FDA-approved medication for the disease is Hetlioz, developed by Vanda Pharmaceuticals Inc. Clinical trials of Hetlioz’s effectiveness were conducted on N24-blind subjects.

Phototherapy and dark exposure (dark therapy) are two of the most commonly prescribed treatments for sighted people (scototherapy).

Lightboxes are commonly used in phototherapy. In order to maintain a regular sleep cycle, the lightbox is utilized in the early morning for a period of two hours at a time. In order to get the most benefit from light therapy, it is recommended to begin treatment when the patient is already waking up at the desired wake time. The retinohypothalamic tract, which connects the retina to the brain, is responsible for registering light and transmitting that information to the brain. Melatonin production is reduced as a result of this signal, which causes the sleep schedule to be shifted. The ideal moment to expose yourself to light is determined by a phase response curve.

Avoiding light exposure late in the day (scototherapy) is the key to achieving dark therapy To avoid the phase-delaying effects of light, patients should wear dark goggles or stay in dimly lit rooms at night or in the evening.

Both light and dark therapy are thought to be more effective when combined. Patients who successfully synchronize to a 24-hour cycle with light and dark therapy are needed to keep up the regimen or the synchronization will be lost.

If you’re having trouble sleeping, melatonin can help. About 4-6 hours before you want to go to bed, take a melatonin supplement. The use of melatonin as a standalone treatment for N24 is rarely successful in patients who are sighted.

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