Have you noticed that you don't go to sleep at the same time every day, and that you seem to go to sleep later and later until you've hit a 24-hour sleep delay? This may sound confusing, but imagine one day you go to sleep at 10 pm and then the next day at 11 pm, and this continues until you find yourself going to sleep at 10 pm again.

This is abnormal, as our circadian rhythm usually helps us go to sleep at the same time every day. If you are having trouble going to sleep every day at the same time, then you may have non-24-hour sleep-wake disorder (N24). Continue reading to find out more about it. 

What is N24? 

N24, or non-24-hour sleep-wake disorder, is a sleep disorder that is an inability of your circadian rhythm to manage your sleep schedule. This means that your biological clock is essentially off. You don't have one, or it is unable to manage your everyday schedule, so you go to sleep at random times. You will go to sleep later and later by minutes or hours until you have completed the clock and made it back to the beginning.

Not only is your sleep impacted, but temperature and hormonal release are also on this same schedule, so attempting to fight it and force yourself to go to sleep at the same time every day can result in severe sleep deprivation. N24 occurs mostly in blind individuals, but can also occur in those with sight. 

Signs and symptoms of N24

A common sign, or potentially the first sign that is noticed, is random bouts of insomnia followed by excessive daytime sleepiness. Insomnia is the inability to go to sleep, and excessive daytime sleepiness is feeling incredibly tired during the day, especially while exposed to light, which should delay the onset of melatonin and any other sleep-inducing feelings. 

These waves will be cyclical, so there are moments when you feel normal because your clock is aligned with society's, but then there are times when your clock is the opposite, and that's when you struggle or feel the symptoms the most. Most individuals have a 24-hour clock, but some even have a 28- or 30-hour clock, further exacerbating the symptoms. 

When allowed to sleep according to your schedule, you may feel relief from these moments of insomnia and fatigue, but at the expense of not being able to keep a daily schedule. But some will continue to feel these symptoms, even if they try to adhere to their schedule, just because of the desynchronization of their clock. 

Without any sort of management and an attempt to stay on a 24-hour clock, these individuals are at extreme risk for the accumulation of their symptoms, including daytime sleepiness, fatigue, depression, and difficulty concentrating or memory problems. Isolation and loneliness are also secondary symptoms due to the clock, causing these individuals to be awake when others are asleep. 

Causes 

In the brain, there is a region in the hypothalamus called the suprachiasmatic nucleus (SCN). The SCN is responsible for maintaining the sleep-wake pattern of the entire body, including influencing the production of melatonin and orexin (two hormones responsible for sleep and wake, respectively), body temperatures (peaking in the morning and dropping at night), and is heavily influenced by light-receiving molecules in the eye. 

When this process is interrupted, the body can no longer maintain its circadian rhythm, and the SCN goes a little rogue. Factors that can interrupt this process include: 

• blindness - no perception of light, which means the SCN doesn't have that extra system to keep it in check, leading to a gradual drifting of the 24-hour cycle. 
• alteration in light sensitivity - dampened perceptions of light, which leads to an inability to truly influence the circadian rhythm.
• environment - isolation with total control of when to turn lights on and off will not receive natural cues. 
• hormonal - a lack of melatonin may lead to the development or perpetuation of N23, which can lead to an inability to regulate the sleep-wake cycle.

Diagnosis 

The initial diagnosis is based on sleep logs by the patient that show a non-24-hour sleep pattern. It's more easily distinguished if the patient's sleep times are not constrained by social or occupational obligations. 

Confirmation of the diagnosis may be done by wearing an actigraphy, which is a device worn on the wrist that tracks the timing of sleep. It should be worn for sufficient time for the sleep cycle to complete one pass around the clock, typically taking several weeks.

A polysomnography is not necessary for diagnosis, so this is very much a disorder reliant on the patient's log of what's happening.  

Therapy

The most widely recommended treatment for sighted patients is exposure to specific regimens of light and dark therapy. A lightbox is useful for phototherapy (light) and is used early in the morning, typically for 2 hours to stabilize the sleep cycle. 

Dark therapy is accomplished by avoiding light exposure late in the day by staying in a dark room or by using special goggles that reduce the amount of light that is allowed in. 

For blind individuals, melatonin therapy is the most recommended, although investigational therapies are looking at other supplements and their impact on the circadian rhythm. 

If you or someone you know is struggling with sleeping, please click the orange button below for a free online sleep test and to get in contact with one of our sleep health professionals.

[Source]:

https://rarediseases.org/rare-diseases/non-24-hour-sleep-wake-disorder/