Did you know that 8 out of 10 blind people suffer from some kind of sleep disorder?
It’s true. Totally blind people (those who cannot perceive light), and many other groups of vision impaired people such as those with achromotopsia (complete color-blindness) and photophobia (extreme light sensitivity) often experience problems falling or staying asleep.
Researchers believe around half of all these blind people may suffer from some kind of serious circadian rhythm disorder.
Non-24-hour-sleep-wake-disorder is the common name for the problem many blind people have. A normal person’s body clock functions on a 25-hour sleep pattern – this is called a circadian rhythm. The transformations of light between day and night produce melatonin in our bodies, which regulate our sleep cycles and automatically reset our body clock to the normal, 24-hour cycle.
But totally blind people, and those with other vision difficulties, struggle with this cycle, because their brain doesn’t receive the message to produce melatonin to regulate the sleep cycle. So a blind person’s sleep cycle tends to fall around 25-hours.
A blind person may sleep normally one night, when their clock is in sync with the day, and then, as the month progresses, even though they go to bed at the same time, it will take them longer and longer to fall asleep. This is known as “free-running”.
This constant free-running of a 25-hour rhythm in a 24 hour day means many blind people feel drowsy and fatigued during the day. For some, this leads to symptoms of depression.
Researchers have found that a daily does of melatonin helps the body to regulate the sleep cycle and people who suffer from non-24-hour-sleep-wake-disorder can experience normal sleep.
The key to successfully taking a melatonin supplement is finding the right time of day to take it, as well as the correct dose. This is the subject of ongoing research by scientists at University of Surrey. The longer your circadian rhythm cycle is, the more difficulty you will have entraining to the 24-hour sleep cycle.
With continued research into the affects of melatonin, found in many herbal sleeping pills, will help put an end to the sleep disorders experienced by people who are blind.