New study: Daytime sleepiness, poor nighttime sleep and snoring all increase the risk of permanent blindness

A recent study published by the UK Biobank in the BMJ Open showed that poor sleep quality, including too much or too little sleep, daytime sleepiness and snoring, may be associated with
an increased risk of developing glaucoma.
Glaucoma is a condition
that causes irreversible vision loss.

The findings highlight the importance of sleep therapy for people at high risk of glaucoma, as well as eye exams for patients with chronic sleep disorders to check for early signs of glaucoma

Glaucoma is the leading cause of blindness, with an estimated 112 million people affected globally by 2040
.
It is characterized by progressive loss of photosensitive cells in the eye and optic nerve damage, the etiology and causative factors of which are unknown
.
But if left untreated, glaucoma can progress to irreversible blindness
.

The researchers believe that while population screening may not be cost-effective, screening for high-risk populations may be cost-effective
.
Previously published research suggests that sleep disturbances may be an important risk factor
.
To explore these questions further, the researchers set out to determine the risk of glaucoma in people with different sleep behaviors: insomnia; Sleeping too much or too little; late or early riser ("owl" or "lark"); Daytime sleepiness; and snoring
.

They sampled 409053 participants from the UK Biobank, all between the ages of 40 and 69 when they were recruited from 2006 to 2010, and provided details
of their sleep behavior.

Sleep time is defined as normal (7 hours to less than 9 hours per day) and too little or too much, outside this range
.
The type of sleep was defined
according to whether the respondent claimed to be an early lark or a night owl.
The severity of insomnia—difficulty falling asleep at night or waking up frequently—is classified as never/sometimes or usual, while subjective daytime sleepiness is classified as never/rare, sometimes or frequent
.

Background information on potential influencing factors was retrieved from questionnaires completed at the time of recruitment: age (average 57 years), gender, race/ethnicity, educational attainment, lifestyle, weight (BMI), and poverty in the area of residence
.
Health and survival of all participants were tracked using medical records and death registry data until the first diagnosis of glaucoma (hospital admission), death, migration, or the end of the surveillance period (March 31, 2021), whichever came first
.

During an average monitoring period of 10.
5 years, 8690 cases of glaucoma
were detected.
People with glaucoma tend to be older, more likely to be male, frequent smokers, and have high blood pressure or diabetes
compared to people with undiagnosed glaucoma.

In addition to sleep type, the other four sleep patterns/behaviors were all associated
with varying degrees of increased risk of glaucoma.
Short or long sleep duration was associated with an 8% increased risk; 12% of insomnia; snoring 4%; Frequent sleepiness during the day (20%)
.
People with snoring and daytime sleepiness are 10% more likely to develop glaucoma compared to people with healthy sleep patterns, while insomniacs and people with short/long sleep patterns are 13%
more likely to develop glaucoma.

When classified according to different types of glaucoma, the results are similar
.

This is an observational study, so the cause
cannot be determined.
The researchers acknowledge that the study relied on self-reporting, not objective measurements, and reflected only one point
in time.
They added that glaucoma itself may affect sleep patterns, not the other way around
.

But the researchers say there may be a plausible biological explanation for the link between sleep disturbances and glaucoma
.
The researchers explain that intraocular pressure is a key factor in the development of glaucoma, and when a person lies down, it rises
when there is an imbalance of sleep hormones, such as insomnia.

They believe that depression and anxiety, often closely related to insomnia, may also increase internal pressure, possibly because cortisol secretion is imbalanced
.
Similarly, repeated or prolonged episodes of cellular hypoxia caused by sleep apnea (sudden cessation of breathing during sleep) may cause direct damage
to the optic nerve.

"Because sleep behavior can be changed, these findings highlight the need for sleep interventions in populations at high risk of glaucoma, as well as potential ophthalmic screening for people with chronic sleep problems, to help prevent glaucoma
," the researchers concluded.

References:

Association of sleep behaviour and pattern with the risk of glaucoma: a prospective cohort study in the UK Biobank” by Cun Sun, Huazhen Yang, Yihan Hu, Yuanyuan Qu, Yao Hu, Yajing Sun, Zhiye Ying and Huan Song, 1 November 2022, BMJ Open.