Blind Non-24 Hour Sleep-Wake Disorder

Author: Vanda Pharmaceuticals
Published: 2011/07/08 - Updated: 2025/05/24
Publication Type: Informative
Category Topic: Sleep Disorders - Academic Publications

Page Content: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This article is about Non-24-Hour Sleep-Wake Disorder (N24HWD), a condition where a person's internal body clock doesn't sync with the standard 24-hour day, causing sleep times to shift daily. It's especially common among totally blind individuals - impacting over 50% of them - since they can't rely on light to regulate their circadian rhythm, though sighted people can experience it too, often tied to things like jet lag or shift work. The piece explains how this disorder leads to tough challenges like insomnia and daytime sleepiness, which can throw a wrench into work, family, and social life, affecting an estimated 65,000 to 95,000 people in the U.S. alone. It's a straightforward, informative read that sheds light on a tricky sleep issue, making it valuable for anyone curious about sleep disorders or dealing with them - especially those with disabilities like blindness, seniors adjusting to changing sleep patterns, or caregivers looking to understand what's going on - Disabled World (DW).

Defining Blind Non-24 Hour Sleep-Wake Disorder (Non-24)

Blind Non-24 Hour Sleep-Wake Disorder (Non-24)

Blind Non-24 Hour Sleep-Wake Disorder (Non-24) is a chronic circadian rhythm disorder primarily affecting individuals who lack light perception, such as those with total blindness. Without light cues to synchronize the body's internal clock with the 24-hour day, sleep and wake cycles drift later each day, following a natural rhythm slightly longer than 24 hours. This leads to recurring periods of severe insomnia, excessive daytime sleepiness, and unpredictable shifts in alertness as the body's sleep-wake pattern moves in and out of alignment with societal norms. The disorder is rooted in the brain's inability to regulate melatonin production due to missing light signals, disrupting the timing of sleep, hormone release, and other physiological processes. Diagnosis often involves tracking sleep logs or actigraphy over weeks, and management focuses on stabilizing rhythms through strict routines, timed melatonin, or prescription medications like tasimelteon. Non-24 is recognized as a lifelong neurological condition, not a behavioral issue, and its impact on daily functioning can be profound.

Introduction

For most people, the clock changes just twice a year for Daylight Saving Time. But for someone with Non-24-Hour Sleep-Wake Disorder (N24HWD, or Non-24), their internal body clock changes every day.

Main Content

In the U.S. alone, it is estimated that approximately 65,000 - 95,000 people suffer from Non-24, a sleep disorder in which a person's sleep period can advance by about 15 minutes each night. Patients suffering from Non-24 experience severe insomnia and excessive daytime sleepiness, which often interferes with social, family and work obligations.

Non-24 is most common in the totally blind who lack light perception and affects more than 50 percent of this population. Sighted people can experience similar sleep or circadian rhythm disorders as well, in the form of jet lag or from night shift work.

Vanda Pharmaceuticals Inc. launched to promote awareness and support for those who may suffer from Non-24. Utilizing the website, people can access helpful information and research articles, listen to interviews conducted with medical experts, and learn about clinical trials.

"Non-24 is a serious health condition and, because many doctors themselves are unaware of the disorder, people can go undiagnosed for years. Though there's still no cure, it's important to have a place for people to go and learn about this condition, know that they're not alone, and then talk to their doctor about their options," said Melanie Brunson, Executive Director of the American Council of the Blind.

Circadian Rhythm

Circadian Rhythm is the daily activity cycle that drives the rhythms of our body- from digestion to hormone secretions to our ability to sleep.

The timing of human sleep is governed by the length of time since a person last slept and by their internal body clock. The body clock or circadian clock controls the timing of human sleep with a rhythm that is regulated by a region of the brain called the suprachiasmatic nucleus (SCN). The SCN, located in the hypothalamus, sends signals to help us stay awake and counteract the effects of fatigue. These signals peak in the evening, when the drive for sleep is high, and then diminish when bedtime approaches.

In most people, the sleep/wake circadian rhythm is maintained on a 24-hour day cycle and determined by the light exposure they get in the morning or evening. When a person's body clock is mismatched with their sleeping and waking schedule, it may create a circadian rhythm sleep disorder.

Insights, Analysis, and Developments

Attribution/Source(s): This quality-reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by Vanda Pharmaceuticals and published on 2011/07/08, this content may have been edited for style, clarity, or brevity.