Each human being’s sleep requirements are varied; ranging from 6 to 10 ½ hours although infants tend to require longer sleep periods than adults. But we each need adequate sleep in order to function effectively. Among the elderly deep sleep is often rare and sometimes it disappears completely. Causal factors for sleep-wake disorder include obstructive sleep apnea, central sleep apnea syndrome, circadian rhythm disruption, narcolepsy, restless leg syndrome and many others.
A 2010 cross-sectional study by Adeoti and Akang revealed that the prevalence of sleep-wake disorders among the blind is significantly high and that there is a strong association between visual loss and the sleep-wake cycle in human beings. In these individuals, the alterations of the intensity of the light reaching the pineal gland through the visual pathway contributes significantly to disruptions in the sleep-wake cycle. A 1999 longitudinal study by Leger and associates conducted among visually impaired individuals and their matched control group revealed that sleep-wake disorder was statistically higher among the blind or almost blind participants than it was among controls. Further, nocturnal disruption of sleep and daytime somnolence were found to be more common among blind participants than among the controls.
Since exposure to ocular light remains the most important environmental synchronizer of the circadian rhythm, it follows that visual impairment with no conscious perception of light increases susceptibility to circadian rhythm misalignment. Lack of light sensitivity which is necessary for resetting and regulating the circadian clock is lacking in people who are totally blind. Eyes are necessary for circadian photoreception to take place. As such, people who are blind are usually not able to entrain their circadian clock to the 24-hour light and dark cycle. However, most individuals who are legally blind but are still able to retain some level of light reception normally have entrained circadian rhythm. The adverse effects of loss of light reception due to blindness, followed by circadian rhythm misalignment resulting in sleep-wake disorder has not been adequately recognized by clinicians, families and employers of blind people. This has made it difficult for blind people with this disorder to seek treatment and/or support services to help them manage the condition. Merely focusing on therapies of sleep-wake disorder such as daytime stimulants and night-time hypnotics is limited to addressing the symptoms only, and neglects the underlying causal factors. The prevalence of sleep-wake disorder is alarming. In the United States alone, of approximately 1.3 million people who are legally blind 10% of them have no photoreception ability. This means that between 65,000 and 95,000 of these people have sleep-wake disorder. The statistics should be even more staggering at global level. This is what prompted the World Sleep Day Committee of the World Association of Sleep Medicine (WASM) to declare March 14th as World Sleep Day (WSD). Its slogan is “Sleep well, stay healthy.” More research is being conducted in this area. More prayers should also ascend to seek wisdom to counter this encroachment on humanity. God is interested not only in our spiritual health but our physical heath as well, (3 John 1:2).
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