68. Non-24 — Not Just a Disorder of the Blind, a guest post24 July 2014 at 03:12 | Posted in Circadian rhythm | 5 Comments
Tags: Guest blogger, Non-24
Perhaps I’ve “arrived”, when Healthline.com approaches me with an offer of a guest post? I said yes, please. So here is the article by their health-and-fitness writer Adrienne:
Thank you Healthline and Adrienne, for the timely article! —D
Non-24 — Not Just a Disorder of the Blind
Non-24-Hour Sleep-Wake Disorder is not a condition that a lot of people were aware of, at least until the first medication for it was approved by the U.S. Food and Drug Administration earlier this year. The advertising for Vanda Pharmaceuticals’ new drug has brought some attention to the disorder, but since the drug is aimed at (and only approved for) those who are blind, few realize that the disorder can and does affect sighted people as well.
Non-24 in Layman’s Terms
Non-24 is a circadian rhythm sleep disorder that causes people to be unable to adjust their sleep-wake cycles to a 24 hour day. This causes their sleep time to progress around the clock. To put it more simply: Each night people who have Non-24 go to sleep later than the night before, each time sleeping in the next day in accordance with the time they went to bed. They go to bed later and later every day, eventually ending back at the same bedtime and starting the cycle all over again. As you can imagine, this doesn’t only interfere with day-to-day responsibilities, but it can also lead to daytime sleepiness, memory issues, depression and more.
Non-24 in the Sighted
In a majority of totally blind people, Non-24 is the result of their inability to perceive light; the lack of light interferes with synchronization of their internal clocks to the day/night cycle in nature. Even though the disorder goes by the same name for the sighted as it does for the blind, the causes are entirely different. Though it’s not currently known just how many sighted people have Non-24, there are several known causes of it.
Here are some of them:
- Changes in light sensitivity. In some sighted people, even though they are able to see well and appear to have great vision, daily light signals may not get through properly, leading to disrupted circadian rhythms.
- Melatonin imbalance. Melatonin, a hormone, plays a part in linking sleep to the day-night cycle. Some sighted people with Non-24 have been found to produce less melatonin than normal while others produce too much. Problems with metabolizing melatonin properly can also impair circadian rhythm and cause Non-24.
- Trauma and physical damage to the brain. Healthy people who suffer head injury can develop Non-24 when the injury damages the circadian and sleep centers of the brain. This can also be the case with brain tumors, such as craniopharyngiomas. For some it’s the brain tumor itself that causes the damage while for others it can be the effect of treatment, such as radiation.
- Environmental factors. Sometimes it’s a sighted person’s exposure to light, or the lack of it, that can interfere with the ability to maintain a 24-hour sleep-wake cycle. An example of this, in scientific studies in the laboratory, is being in an isolated environment without access any clues as to what time of the day it is, and not being allowed to turn lights on or off as desired. In such studies healthy people will temporarily acquire a non-24 sleep pattern, though, of course, not the disorder.
- Individual sleep patterns. According to The National Organization for Rare Disorders (NORD), a person’s need for sleep could lead to a Non-24 sleep cycle. They give the example of a healthy person who may sleep 8 hours and stay awake for 16 while another person may need 12 hours of sleep but still be awake for the normal 16 hours, leading to a 28-hour day. The same can happen for a person who sleeps the normal 8 hours but then requires 20 hours of awake time before sleep again is possible, also leading to a 28-hour day.
These are just some of the known or suspected causes of Non-24 in the sighted.
- (January 2014). FDA approves Hetlioz: first treatment for non-24 hour sleep-wake disorder in blind individuals. U.S. Food and Drug Administration. Retrieved June 28, 2014 from http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm384092.htm?utm_source=rss&utm_medium=rss&utm_campaign=fda-approves-hetlioz-first-treatment-for-non-24-hour-sleep-wake-disorder-in-blind-individuals
- (2013). Non-24 in Sighted vs. Blind People. National Sleep Foundation. Retrieved June 29, 2014, from http://sleepfoundation.org/non-24/blind.html
- Fadden, James S.P. MA, Vice-President, Sharkey, Katherine MD, PhD, NORD. (March 2013). NON-24-HOUR SLEEP-WAKE DISORDER. National Organization for Rare Disorders (NORD). Retrieved June 28, 2014, from https://www.rarediseases.org/rare-disease-information/rare-diseases/byID/1275/viewFullReport
Adrienne is a freelance writer and author who has written extensively on all things health and fitness for more than a decade. You can connect with Adrienne on Facebook here.
Healthline.com is funded, apparently exclusively, by advertising and they own, are owned by or are affiliated with Healthline Networks, Inc., Healthline Corp and YourDoctor.com
Their goal is to educate and empower users with relevant and responsible information in order to foster better communication between doctors and patients.
You can go to http://www.healthline.com for more information on sleep disorders and other related conditions.
69. Next post: –another guest post–