SHED SOME LIGHT… on Non-24 Disorder

You may have seen commercials for a new drug, Hetlioz, airing on TV the last few weeks for a mysterious condition called Non-24 Circadian Rhythm Disorder (also known as Non-24, N24 or free running disorder). Non-24 is considered a circadian rhythm disorder which occurs in both blind people and people who are sighted. Those with Non-24 can struggle to keep to a regular schedule of work or classes. Those who are blind run a 40-70 percent risk of suffering from this disorder, which researchers still don’t understand fully, as it can equally effect people who have their sight.

Here are some good questions that help doctors to identify people struggling with Non-24 Disorder:

  • Do you struggle to fall asleep or stay asleep at night?
  • Do you find you are sometimes excessively sleepy at inappropriate times during the day?
  • Do you find it hard to concentrate on tasks?
  • Do you feel like you are never well rested even after sleeping?
  • Do you sleep at times that are remarkably different from those around you?
  • Do you feel as if you are the only one who has your sleep schedule?

It is important to see a doctor about these concerns as they point to multiple kinds of sleep disorders. And like many other sleep problems, Non-24 shares two major symptoms:

1. The inability to fall and/or stay asleep at night.
2. An overwhelming urge to sleep during the day.

These symptoms can point to the improper timing of hormone release in the body, primarily of two sleep-related hormones: melatonin (which encourages sleep) and cortisol (which encourages wakefulness and appetite). When these hormones run out of sync with one another they can impact the phasing which leads to normal sleep patterns. On top of that, sleep deprivation that comes as a result can lead to daytime cognitive dysfunction and mood disorders.

Those with Non-24 Disorder have brains which do not adequately time the release of the sleep-wake hormones melatonin and cortisol due to an abnormal circadian clock, which is found inside the brain (the suprachiasmatic nucleus, or SCN). As a result, their sleep-wake and other critical rhythms shift off schedule gradually every day, leading to significant disruptions in sleep-wake function until the circadian clock is eventually reset. 

Thanks to HetliozPro for use of this diagram.

Why do the hormones fall out of rhythm? Science isn’t sure. Most people have circadian rhythms that run around 24 hours; the cycles of sleep-wake and other drives rely on the regular timing of hormones in conjunction with external time cues (like light and dark) to keep these rhythms on track.

Somebody with Non-24 has a body clock which is set for longer or shorter than the 24 hour clock that most people function on, so they basically shift a little earlier or later each day in comparison to everyone else until their rhythms align outside of what is considered a normal schedule. Hence, they can become sleepy during the day due to a persistent shift in rhythms that forces their sleep drive to kick in at times which are incongruent with social norms.

For people who are sighted, Non-24 is fairly rare, but it may be amended by the use of light cues and phototherapy, matched with forced sleep schedules, to help inform the sleep drive mechanisms in the body. Managing light exposure is key to making melatonin work. However, those who are blind are less able (or unable) to use light exposure effectively to control melatonin production and need to try other methods to keep from “free running.”

How it Non-24 treated? Carefully timed phototherapy can help some people regain a regular rhythm or at least offset deep shifts so they can manage normal job or school schedules. A new melatonin receptor, Hetlioz (tasimelteon), was approved earlier this year by the FDA to treat Non-24 and can be obtained by prescription through specialty pharmacies.

For more information about Non-24, please visit these excellent websites.

Non-24 Hour Sleep-Wake Disorder || Facts & Prevalence || NSF
Circadian Sleep Disorders Network Non-24 Q&A

About Tamara Kaye Sellman (621 Articles)

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