Non-24-Hour Sleep-Wake Disorder

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Non-24-Hour Sleep-Wake Disorder Definition

The body clock, also known as the circadian rhythm, is a 24-hour cycle that affects sleep timing, hunger, and energy levels. The circadian rhythm is affected by sleep timing, appetite, and energy levels. The suprachiasmatic nucleus (SCN) in the brain regulates the circadian rhythm.

Most people have a natural body clock that lasts slightly longer than 24 hours. The SCN, on the other hand, uses ambient light and other “zeitgebers” (time-givers) to keep us in sync with the 24-hour rhythm. Sleep onset is triggered by the SCN when it sends an alert to the release of the sleep hormone melatonin after it gets dark.

Non-24-hour sleep-wake disorder, formerly known as free-running rhythm disorder or hypernychthemeral syndrome, is when the body clock becomes out of sync with the environment.

What Is Non-24-Hour Sleep-Wake Disorder

Individuals with non-24-hour sleep-wake disorder (N24SWD) have a shorter circadian rhythm or, more often, slightly longer than 24 hours. This causes sleep and waking times to shift progressively earlier or later over time, usually by one to two hours at a time. The circadian rhythm gets misaligned from regular daylight hours over days or weeks.

Individuals with N24SWD endure abnormal variations in hunger, mood, and attentiveness due to this ever-shifting rhythm. In addition, they have a natural propensity for resting in the middle of the day and trouble sleeping at night when their body clock is substantially desynchronized. As a result, they may not display any symptoms many weeks later as their internal clock catches up with daylight once more.

Even when reinforced with standard treatments such as caffeine4, attempts to maintain a regular sleep-wake cycle are unsuccessful. Desynchronization from the intrinsic circadian rhythm may have adverse health repercussions in the long run.

Individuals with non-24-hour sleep-wake disorder frequently have difficulty keeping work, school, or social obligations. In addition, they may become depressed due to the pressure of not being able to maintain a typical routine or sleeping during the day and not receiving enough sunlight.

Non-24-Hour Sleep-Wake Disorder vs. Other Circadian Disorders: What’s the Difference?

One of six circadian rhythm sleep disorders is a non-24-hour sleep-wake disorder. Because the condition is primarily caused by internal reasons rather than external factors like jet lag or shift work, it is classified as an intrinsic sleep-wake disorder.

Advanced and delayed sleep-wake phase disorders are another group of circadian rhythm abnormalities. In these cases, the sleep-wake cycle is advanced or delayed considerably. There is an irregular sleep-wake rhythm disorder in which individuals have a disrupted sleep pattern 

What Are Sleep Disorders?

The sleep disorders are listed below:

Circadian Rhythm Disorders

People generally sleep in the evening, thanks not only to societal norms but also to the close interaction between our natural sleep and alertness rhythms, which are driven by an internal “clock.”

the suprachiasmatic nucleus present in the hypothalamus is a tiny portion of the brain responsible for our circadian rhythm. It’s located just above the optic nerve. Light and exercise “resynchronize” and can advance or delay the clock. Circadian rhythm disorders (or “circadian rhythm anomalies”) are diseases associated with this clock (meaning “about” or “dying”).

Jet lag, shift work adaptations, delayed sleep phase syndrome (falling asleep and waking up too late), and advanced sleep phase syndrome are all examples of circadian rhythm disturbances (you fall asleep and wake up too early).


People who have insomnia don’t feel like they get enough sleep at night. As a result, they might have trouble falling asleep or waking up frequently during the night or early in the morning. Insomnia is a problem if it harms your daily activities. Insomnia has several possible causes: stress, anxiety, depression, poor sleeping habits, circadian rhythm disorders (such as jet lag), and taking certain medicines.


Snoring is common among adults. The sound occurs when the air you breathe rattles over the relaxed tissues of your throat. Snoring may be frustrating simply because of the noise it generates. However, it might also indicate a more severe sleep issue called sleep apnea, which affects one in five adults and is characterized by abnormal pauses in breathing during sleep apnea.

Sleep Apnea

Sleep apnea is an experience in which the upper airway becomes wholly or partially blocked, disrupting regular breathing for brief periods, which then awakens you up. It might lead to significant daytime drowsiness. Untreated severe sleep apnea has been linked to high blood pressure and an increased risk of stroke and heart attack.

Pregnancy and Sleep

Many women endure sleepless nights and general tiredness in the first and third trimesters of pregnancy. Frequent trips to the toilet and morning sickness in the early stages of pregnancy might cause sleep problems. Vivid dreams and physical discomfort may prevent deep sleep later in pregnancy. In addition, the new baby’s care or the mother’s postpartum depression may disrupt rest after delivery.

NON 24 not blind

"Although this condition is most common in blind people, it can happen to anybody."
Circadian rhythm disorders are diseases associated with the clock

An irregular sleep-wake rhythm disorder in which individuals have a disrupted sleep pattern with napping the day and long periods awake at night.

Advanced and delayed sleep-wake phase disorders are another group of circadian rhythm abnormalities. In these cases, the sleep-wake cycle is advanced or delayed considerably, and there is an irregular sleep-wake rhythm disorder in which individuals have a disrupted sleep pattern with napping throughout the day and long periods awake at night. As a new mother has trouble sleeping because her baby keeps her up all night.”

“Racing thoughts during the day can make it hard to fall asleep at night. Many people with insomnia complain of difficulty falling back to sleep once they wake up in the middle of the night. As a young boy has trouble sleeping due to his fear of monsters under the bed.

Delayed Sleep Phase Disorder

People with this disorder have an internal body clock delayed by 2-3 hours. Their circadian rhythms are not in sync with society’s normal rhythm of sleeping during the nighttime and being awake during daylight hours.

As a result, most people diagnosed with DSPS find themselves unable to fall asleep until very early in the morning between 2 or 3 a.m. And unable to wake until late morning or early afternoon, regardless of how much sleep they’ve gotten.”

“For people with DSPS, the timing of their internal body clock is shifted around so that their usual bedtime falls after 3 a.m. As a teenager has trouble falling asleep at night because he needs to get up for school in the morning.”

Advanced Sleep Phase Disorder

People with this disorder have an internal body clock that is advanced by about 2 hours, meaning their circadian rhythms are ahead of society’s normal rhythm of sleeping during the night time and being awake during daylight hours.

As a result, most people diagnosed with ASPD find themselves wide awake at 10 p.m., with an urge to go to bed early. They may be sleepy during the morning hours.

For people with ASPD, the timing of their internal body clock is shifted around so that their usual bedtime falls before 8 p.m.As an elderly man finds himself falling asleep at 7 each night and waking up at 4 a.m.”

A shift in sleep patterns can occur when traveling across time zones or working irregular shifts.

Shift work disorder

Shift work disorder, classified as a circadian rhythm disorder, is often related to changing work schedules. It can affect anyone whose job requires them to work outside normal daytime working hours such as nurses who work the night shift. People who work evening shifts often have trouble falling asleep as early as they used to.

Circadian rhythm sleep disorders are less frequent in those who practice good sleep hygiene.

Good sleep habits can help improve the symptoms of people with circadian rhythm sleep disorders. And reduce their chances of developing other psychiatric conditions. Such as depression and anxiety. A student begins using caffeine during the day because she can’t fall asleep at night.

Non-24 blindness sleep disorder

This is a sleep disorder in which individuals do not have a typical 24-hour sleep-wake cycle. Instead, due to various circumstances, people with this disorder may find themselves awake and alert at night time while experiencing extreme drowsiness during the day.

People with Non-24 can also experience symptoms such as irregular sleep patterns, extreme tiredness, and constant yawning. For example, a college student shifts his work schedule so that he can attend classes during the day and work at night.”

Non 24 blindness

Individuals who suffer from this disorder usually lack adequate photoreceptor cells in their eyes necessary for normal vision, meaning they cannot accurately process the information daily due to the lack of light perception.

In addition to the other symptoms mentioned, individuals with Non-24 may also experience “sensitivity to bright light” and a “feeling of never being fully awake.”

For example, A young girl living in a dorm room feels extremely tired during her classes and often has trouble studying because she cannot keep her eyes open.”

Free-running sleep disorder

A shift in sleep patterns can occur when traveling across time zones or working irregular shifts. People who suffer from this disorder cannot shift their internal timing without exposure to daylight. 

Because free-running people do not have an external time cue known as a zeitgeber, it is very difficult for them to adapt to society’s normal sleep schedules. For example, she has trouble sleeping during her daytime classes because she was taught growing up that school starts at 8:30 and she needs the sunlight to stay awake.

People with this disorder experience insomnia while trying to maintain a regular sleep or wake schedule. Example: He usually sleeps 3 hours every night but still feels tired throughout the day.

Circadian rhythm disorder blindness

As mentioned above, those with Non-24 will generally lack adequate photoreceptor cells in their eyes necessary for normal vision. Due to the lack of light perception, those who suffer from this disorder will experience extreme drowsiness during the day and insomnia at night. 

What happens after damage to the suprachiasmatic nucleus itself?

After the damage to the SCN, people experience more severe symptoms of sleep disorder conditions. For example, shift work disorder appears when there is damage to the SCN, and the individual has trouble traveling between their internal clock and civilian time. Due to damage to her suprachiasmatic nucleus, she often misses days of class because she cannot fall asleep in the morning or stay awake at night.

What happens when the circadian rhythm is disrupted?

A person may have difficulty falling asleep, wake up during the night, or be not able to sleep as per their needs in the morning if their body’s internal clock isn’t sending correct signals. As a result, their total sleep time can be reduced, and a disrupted circadian rhythm might also result in less deep, fractured, and lower-quality sleep.

Can a Sighted Person Have Non-24-Hour Sleep-Wake Disorder?

Non-24-hour sleep-wake disorder can also affect those who are blind. 10. Non-24 hour sleep-wake disorder affects people who are blind, as well as those with vision impairments. Unfortunately, symptoms include daytime tiredness and nighttime sleeplessness. 

So N24SWD is frequently misdiagnosed as another sleep problem in sighted persons. As a result, many sighted individuals suffer from it for years before being diagnosed.

In people who are blind, it’s unknown what causes non-24-hour sleep-wake disorder. The most comprehensive research of sighted individuals with N24SWD discovered that most were male and had symptoms that began in the teens or twenties. The non-24-hour sleep-wake disease may have a genetic component, although it is uncommon within families and can occur even if a person has multiple risk factors.

Before being diagnosed with N24SWD, people who have been seen with the disease often have a delayed sleep-wake cycle. N24SWD may occur spontaneously in persons with a weak circadian clock due to staying up late for many years and getting too much nocturnal exposure to light, according to researchers.

Many sighted people with N24SWD have a history of mental illness, such as major depression, bipolar disorder, obsessive-compulsive disorder, schizophrenia, or schizoid personality disorder. N24SWD may have evolved in these people due to social isolation and other symptoms of their disease.

In some situations, non-24-hour sleep-wake syndrome in blind people is linked to a traumatic brain injury. Damage to cells in the retina14, connecting the retina and the SCN, melatonin production pathway regulation route, or even the SCN itself may disrupt or weaken the body clock.


Doctors may administer bright light treatment in the morning and melatonin supplements at night to cure N24SWD in sighted persons. However, patients should begin therapy as soon after their body clock naturally shifts within one to two hours of their intended bedtime as possible to get the best results. We hope you liked the information written in this article along with the sources mentioned above if you have any further queries regarding this topic. Don’t hesitate to leave a comment below.

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Ask Ameer

Ameer is the content director of Sleepingmentor, which means he not only reviews new mattresses, bedsheets, pillows, and mattress toppers every week, but also curates all the comparisons, best of pages, reviews pages, and vs pages on the site. He takes a straightforward, honest approach to his reviews. He covers sleep science by researching a lot on Google and finding meaningful content which entertains his users.

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