Sleeping well has benefits for the health of the body and mind that have been scientifically proven; in fact, a recent study shows that it protects against the risk of heart disease and stroke, while another associates little sleep with more chances of developing various chronic diseases. Now, new research warns that poor-quality sleep, including sleeping too much or too little, experiencing daytime sleepiness or snoring, may be linked to an increased risk of irreversible vision loss from glaucoma.
The results of this large UK Biobank study highlight the need for people at high risk of developing glaucoma to undergo sleep therapy and for those with chronic sleep disorders to have eye checks to make it possible detect if they present early signs of glaucoma, according to the authors of the work in an article published in BMJ Open.
Glaucoma is characterized by a progressive loss of light-sensitive cells in the eye and a deterioration of the optic nerve. The causes and factors that contribute to the appearance of this eye disease are not well understood, but if patients do not receive adequate treatment it can progress to irreversible blindness. It is currently one of the main causes of blindness worldwide and it is estimated that it will affect around 112 million people in 2040.
Inadequate sleep patterns that increase the risk of glaucoma
The researchers decided to assess the risk of developing glaucoma in people with different sleep habits: sleeping too much or too little, suffering from insomnia, having nocturnal or morning chronotypes (popularly known as ‘owls’ or ‘larks’), presenting daytime sleepiness and snoring. . To do this, they selected 409,053 participants in the UK Biobank, who were between 40 and 69 years old in 2006-10 when they were recruited, and who had reported their sleep behaviours.
Short or long sleep was associated with an 8% increased risk of glaucoma; insomnia with 12% more; snoring with 4% more, and frequent daytime sleepiness with 20% more
They defined as normal a sleep duration of 7 to less than 9 hours per day, while outside this range it was considered too little or too much. The chronotype was established based on whether the person described themselves as a morning lark or a night owl. Insomnia severity (difficulty falling asleep at night or frequent awakenings) was classified as never, sometimes, or usually, while subjective daytime sleepiness was classified as never, rarely, sometimes, or frequently.
At the time of recruitment, the participants had answered questionnaires detailing other factors that could influence the results, such as their age (57 on average), gender, educational level, weight (body mass index, BMI), or race. Medical records and death registration data were also used to track their health and survival until a first diagnosis of glaucoma (hospital admission), death, emigration, or the end of the follow-up period (31 March 2021), whichever comes first.
8,690 cases of glaucoma were detected during the average follow-up period of just over 10.5 years. Individuals with glaucoma tended to be older and more likely to be male, chronic smokers, and have hypertension or diabetes than those who were not diagnosed with glaucoma. With the exception of chronotype, the other four sleep patterns or behaviors were associated with varying degrees of increased risk of glaucoma.
Thus, a short or long duration sleep was associated with an 8% higher risk; insomnia with 12% more; snoring with 4% more, and frequent daytime sleepiness with 20% more. People who snored and those who experienced daytime sleepiness were 10% more likely to develop glaucoma, while people with insomnia and those who had a short- or long-duration sleep pattern were 13% more likely to have it, compared with individuals who enjoyed a healthy sleep pattern. These results were similar when classified by different types of glaucoma.
Why sleep disturbances are associated with glaucoma
As it is an observational study that has been based on data offered by the participants during a certain period of time, it has not been possible to establish a cause, according to its authors, who point out that it could be glaucoma that influenced the patterns of dream, and not the other way around. However, they argue that there are potentially plausible biological explanations for the associations between sleep disturbance and glaucoma that they have found.
The internal pressure of the eye or intraocular pressure is a fundamental factor in the development of glaucoma and increases when a person is lying down and when sleep hormones are unbalanced, as occurs in insomnia, the researchers explained, adding that depression and Anxiety, which often accompanies insomnia, can also increase internal eye pressure, possibly due to dysregulated cortisol production, they note.
On the other hand, it has also been suggested that repeated or prolonged episodes of low cellular oxygen levels due to sleep apnea, whose main symptom is a sudden stop in breathing during sleep, could cause a direct damage to the optic nerve.
“Since sleep behaviors are modifiable, these findings underscore the need for sleep intervention for people at high risk of glaucoma and possible ophthalmologic screening among people with chronic sleep problems to help prevent glaucoma,” they conclude. the researchers.
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