Abstract
Purpose: :
Sleep-wake cycles and the circadian rhythm are primarily established by the synchronization of light detection by photosensitive retinal ganglion cells and the consequent release of melatonin by the pineal gland. Sleep disturbances have been reported in many blind individuals, as well as in individuals with pineal gland damage. Research has demonstrated that among genetically caused retinal dystrophies, some genes are expressed only in the retina while others are expressed both in the retina and the pineal gland. This study investigates sleep disturbances in individuals with genetically caused retinal dystrophies, either involving only the retina or both the retina and the pineal gland, in order to determine if there is an effect of gene expression on sleep quality.
Methods: :
Data were collected for 27 individuals with genetically caused retinal dystrophy (20 retinal expression only, 7 retinal and pineal expression). All participants were interviewed using the Pittsburgh Sleep Quality Index (PSQI), a 19-question scale evaluating seven major components of sleep quality. The Brief General Health Assessment Questionnaire was used to determine any other possible explanations for sleep disturbances (ex: shift work, systemic disorders, excessive caffeine or medication use). Genetic information was collected from the patient files of the McGill Ocular Genetics Centre at the Montreal Children’s Hospital.
Results: :
No significant difference in sleep quality was found between those with gene expression in the retina only and those with gene expression in the retina and pineal gland. However, both groups demonstrated abnormally poor sleep quality with regular sleep disturbances. Furthermore, although there was no significant difference between the two groups, the individuals with gene expression in the retina and the pineal gland had poorer scores on the PSQI (Mean=8.57 versus Mean=6.70 for retinal expression only, where 5 and below is considered normal) suggesting a trend in this direction.
Conclusions: :
Although no significant difference was found between individuals with gene expression in the retina only and those with gene expression in the retina and the pineal gland, both groups do experience abnormally poor sleep quality, with a trend supporting existing research and our hypothesis.
Keywords: gene/expression • circadian rhythms • retinal degenerations: hereditary