[Nfbf-l] Non-24-hour sleep-wake disorder occurs in a great majority of individuals who are totally blind

[Alan Dicey via Nfbf-l]

Dear Friends,
Passing this along.
With Best Regards,
God Bless,
Alan
Plantation, Florida

Non-24-hour sleep-wake disorder (N24HSWD) occurs in a great majority of 
individuals who are totally blind and lack the light sensitivity necessary 
to reset their body clock. As a result, these individuals suffer from sleep 
deprivation, which may lead to difficulties with concentration and memory, 
as well as an increased risk of errors, accidents, bouts of depression and 
lack of energy. For many totally blind individuals the sleepless nights and 
daytime fatigue are considered the most disabling aspects of their 
blindness.

The timing of human sleep is governed by the length of time since a person 
last slept and by their internal body clock. The internal body clock, or 
circadian pacemaker, controls the timing of human sleep with a rhythm that 
is regulated by a tiny region of the brain called the suprachiasmatic 
nucleus (SCN). Signals from the SCN 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.

The intrinsic circadian body clock regulates biological functions in an 
approximate 24-hour cycle and requires regular input from the environment to 
help maintain synchrony to the 24-hour day. In most people, circadian 
rhythms are precisely synchronized to the 24-hour day by exposure to 
environmental synchronizers such as light. Without light, an individual may 
"free run" slightly longer or shorter than 24 hours, causing a slight delay 
or advance in their body clock each day.

This misalignment between an individual's body clock and their sleep/wake 
schedule may result in a circadian rhythm sleep disorder (CRSD), a 
non-24-hour sleep-wake disorder. As a result, the sleep-wake cycle of these 
individuals moves gradually later and later each day if their circadian 
period is more than 24 hours, or earlier and earlier if it is less than 24 
hours. This condition occurs often in subjects who are totally blind and 
lack the light sensitivity necessary to reset the circadian clock.

It is estimated that about 1.3 million Americans are legally blind, with 
approximately 10 percent having no light perception. Clinical studies 
estimate that about 50 percent of totally blind individuals suffer from 
N24HSWD. Thus, approximately 65,000 Americans may suffer from this disorder. 
The "free running" of the body clock results in an approximately 
one-to-four-month repeating cycle where the clock continually shifts about 
15 minutes a day until the cycle repeats itself. As time progresses, the 
internal circadian rhythm of these individuals moves farther and farther 
away from the 24-hour light-dark cycle, which gradually makes sleeping at 
night virtually impossible and leads to extreme sleepiness during daytime 
hours.

Eventually, the individual's sleep-wake cycle moves back into alignment with 
the night, and "free-running" individuals are once again able to sleep well 
at night. However, the alignment between the internal circadian rhythm and 
the 24-hour light-dark cycle is only temporary.

In addition to cyclical nighttime sleep and daytime sleepiness problems, 
this condition can cause daily shifts in body temperature and hormone 
secretion, and is sometimes associated with depression symptoms and mood 
disorders.

If you suffer from not being able to sleep nights, tell your physician. 
There are some natural medications, other than just sleeping pills, that 
help a person to sleep better. In addition, a new medication was recently 
approved by the FDA that will greatly help those suffering from sleepless 
nights. So if you are having trouble sleeping, tell your physician and get 
the help you need. Then, wake in the morning to have a great day.

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