Non-24-hour sleep-wake syndrome, also called free-running type or non-24-hour circadian rhythm disorder, is one of many circadian rhythm disorders and probably the rarest and most difficult to correct of all of them. Most people have an internal biological clock, or circadian rhythm, that roughly adheres to a 24 hour schedule. There may be slight daily variances in waking and sleeping onset times, but these all generally even out over a longer stretch of time. Even those with advanced or delayed circadian rhythm disorders function within this 24 hour schedule.
Those with non-24-hour sleep-wake syndrome do not have internal clocks that reset and stay balanced within a 24 hour schedule. In most cases, their circadian rhythms are set on longer loops, usually resulting in 25 or 26 hour cycles, or even more in some cases. There have documented cases of people having as dramatic as 72 hour cycles, in which they would stay awake for 48 straight hours, and then sleep for 24 straight hours as a regular sleeping pattern. There are only a few known dramatic cases such as that though, and most cases fall within the 25 or 26 hour range.
What this means for these individuals is that their sleep and wake times are pushed back by 1 or 2 hours every day. This leads to a constant cycle between sleep times that are considered unconventional by society’s standards, with occasional short stops in conventional time frames before progressing on again into unconventional. This extremely unbalanced sleeping schedule makes it all but impossible for the subject to hold a traditional job, or attend regularly scheduled school classes unless they fight the disorder, which is not easy without the proper treatment. individuals living with this have often found their 'calling' working in a self employed capacity, or in a number of other fields of work where they can effectively set their own work schedule. Those still attending school may find it necessary to take home schooling through the internet or other avenues.
Apart from the social stress or depression that living with non-24 hour disorder may cause, the disorder itself is not considered harmful. The actual quality of sleep, and more importantly deep sleep, is equal or in many cases better, than those without the disorder.
Non-24-hour sleep wake disorder is very common among blind people, with more than 50% of blind people having it. Though they have fully functioning biological clocks, without the light cues to balance and reset it on, the circadian rhythm often becomes unbalanced. This condition is quite rare in those with sight, but can occur. Having unstructured or irregular daily routines, bad sleeping habits, and poor exposure to sunlight on a consistent basis can all be factors in the development of this disorder.
There are also studies showing a link between delayed sleep phase disorder and non-24-hour sleep-wake syndrome, in that those with delayed sleep phase are at a higher risk of developing free-running type.
In most cases, a doctor should be consulted regarding this disorder. Even if it is not causing conflict with work or other activities, it may be that it is affecting your relationships with family or friends, which could lead to stress and depression, and other sleeping problems or mental health issues as a result.
A doctor will need to have a history of your past sleeping routines, as well as your medical history and be informed of any recent changes in your life that may be contributing to the disorder. Any drug or medication use will also need to be documented. You may be subjected to a neurological test as well. Additionally, you may need to have your body temperature and melatonin levels examined.
Once the disorder has been diagnosed, which will not require an overnight sleep study, the treatment plans can begin. The first area will target changes you can make in your routine in an attempt to reset and balance your circadian rhythm. This will include incorporating fixed events into your schedule at set times no matter when you wake up, to try and root your internal clock to a 24 hour rhythm.
Melatonin is the most widely used treatment, and is typically ingested within a few hours of the desired bedtime. This can be helpful in rooting your bedtime. Light treatment for sighted people, chronotherapy and acupuncture have all been used as well with varying results.
It is common of all treatment methods that they take a long process before showing any results, and some subjects have shown extreme resistance to all therapies. Like many sleeping disorders there is no cure in a traditional sense, and the disorder must be constantly monitored and effective treatments for the patient actively continued. Maintaining a sleep diary after starting on any treatment plan will help a doctor in determining the success rate of the plan, and whether it should be maintained, abandoned in favor of another treatment option, or merged with another plan.
© 2021 American Sleep Association.