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How well you sleep at night may be linked to your risk of developing irreversible sight loss, or glaucoma, according to a study published in BMJ Open.
Sleeping for too long or not long enough, insomnia, snoring and frequent daytime sleepiness were all found to significantly increase the risk of glaucoma.
The researchers say the findings should prompt those at high risk of glaucoma to discuss sleep interventions with their doctor.
Participants were followed up for over a decade
The study was based on data from more than 409,00 participants in the UK Biobank study, all of whom were aged between 40 and 69 when recruited.
All participants provided details of their sleep behaviours as well as other potentially influential factors, such as age, sex, race/ethnicity, educational attainment, lifestyle, weight and residential area of deprivation.
Normal sleep duration was considered to be between seven to nine hours per night, insomnia was defined as trouble falling asleep or frequent waking (participants asked to select never/sometimes or usually) and subjective daytime sleepiness was categorised as never/rarely, sometimes, or frequent.
Participants were followed up for an average of 10.5 years, and medical records and death registration data were used to track the health and survival of all who took part in the study.
Frequent daytime sleepiness was associated with an increased risk of sight loss
In total, 8,690 cases of glaucoma were identified. These participants tended to be older and were more likely to be male, an ever smoker and have high blood pressure or diabetes compared to those without.
Four sleep behaviours were associated with varying degrees of heightened glaucoma risk: short or long sleep duration was associated with an 8% heightened risk; insomnia 12%; snoring 4%; and frequent daytime sleepiness 20%.
And compared with those with a healthy sleep pattern, snorers and those who experienced daytime sleepiness were 10% more likely to have glaucoma, while insomniacs and those with a short/long sleep duration pattern were 13% more likely to have it.
The results were similar when categorised by different types of glaucoma.
Ophthalmologic screening could help to prevent glaucoma
The authors of the research warn that the study is observational and cannot establish a cause. However, there are some plausible explanations for the findings. These are:
- When a person is lying down and when sleep hormones are out of kilter, the internal pressure of the eye rises. This is a key factor in the development of glaucoma.
- Depression and anxiety may also increase internal eye pressure, and these two disorders are closely linked to insomnia.
- Sleep apnoea can cause repetitive or prolonged episodes of low levels of cellular oxygen, which may cause direct damage to the optic nerve.
However, they add that glaucoma might itself influence sleep patterns, rather than the other way around.
Nevertheless, they suggest that individuals at heightened risk of glaucoma should seek out sleep interventions to lower their risk. They add that ophthalmologic screening among individuals with chronic sleep problems could also help lower rates of glaucoma.