Sleep, Eye Pressure, and Glaucoma: What the Science Really Shows

Sleep, Eye Pressure, and Glaucoma: What the Science Really Shows

When we think about glaucoma risk, sleep is rarely part of the conversation. Yet mounting evidence shows that how—and how well—you sleep can significantly influence eye pressure, optic nerve health, and glaucoma progression.

Glaucoma is not only a disease of eye pressure. It is a disease of the optic nerve, and the optic nerve is especially vulnerable to changes in pressure, oxygen delivery, and blood flow—all of which fluctuate during sleep.

Eye Pressure Rises at Night

In healthy individuals, intraocular pressure (IOP) follows a natural circadian rhythm, typically rising at night, especially when lying flat. Multiple studies have shown that eye pressure increases when we move from a seated or upright position to a supine position, and even more so during sleep.

For patients with glaucoma or glaucoma suspects, these nocturnal IOP elevations may be more pronounced and potentially more damaging to the optic nerve, particularly because they often go undetected during daytime office visits.

Side-Sleeping and Asymmetric Glaucoma

Sleep position matters.

Research has demonstrated that sleeping on one side can increase eye pressure in the dependent (downward-facing) eye. Over time, this may contribute to asymmetric glaucoma, where one eye shows more optic nerve damage or visual field loss than the other.

Several studies have found correlations between preferred sleeping side and the eye with more advanced glaucoma damage. This does not mean side-sleeping causes glaucoma—but in susceptible individuals, it may be a modifiable risk factor worth addressing.

Sleep Apnea and Glaucoma Risk

One of the strongest sleep-related risk factors for glaucoma is obstructive sleep apnea (OSA).

OSA causes repeated episodes of airway obstruction during sleep, leading to intermittent hypoxia (low oxygen levels), surges in blood pressure, and impaired blood flow regulation. The optic nerve, which already has a delicate blood supply, may be particularly vulnerable to these changes.

Large population studies and meta-analyses have shown that people with sleep apnea have a higher prevalence of glaucoma, independent of eye pressure. Importantly, this association has been observed even in patients without elevated IOP, suggesting a vascular and hypoxic mechanism rather than a pressure-only effect.

If you have glaucoma or are at risk, and also snore loudly, wake up unrefreshed, or experience daytime sleepiness, a sleep evaluation may be medically important, not optional.

Nocturnal Hypotension: When Blood Pressure Drops Too Low

Another underrecognized risk factor is nocturnal hypotension, or excessive drops in blood pressure during sleep.

While blood pressure normally decreases at night, overly aggressive dipping—especially in patients taking nighttime antihypertensive medications—can reduce optic nerve perfusion pressure. This means the optic nerve may not receive enough blood flow during sleep, precisely when eye pressure is higher.

Multiple studies have linked nocturnal hypotension to glaucoma progression, particularly in normal-tension glaucoma. In these cases, optic nerve damage may occur despite “normal” eye pressures because blood flow is insufficient.

This is why glaucoma care should sometimes involve coordination with a patient’s primary care physician or cardiologist—especially when progressive damage occurs despite good pressure control.

Practical Sleep Strategies for Glaucoma Patients

While sleep is not a replacement for medical or surgical glaucoma treatment, optimizing sleep can support optic nerve health:

• Avoid prolonged side-sleeping on the more affected eye. Use a pillow with a face cut-out.  

• Consider a slight head elevation during sleep, about 20-30 degrees 

• Do not stop blood pressure medications—but discuss timing with your physician 

• Screen for sleep apnea if symptoms are present. Use the free app, Snore Lab, to record your sleep, and then discuss this with your primary doctor. 

• Prioritize consistent, high-quality sleep to support vascular health

The Bigger Picture

Glaucoma management is evolving. Lowering eye pressure remains essential—but it is no longer the only variable that matters.

Sleep quality, sleep position, oxygenation, and nighttime blood pressure all influence the delicate balance between eye pressure and optic nerve perfusion. Understanding and addressing these factors can help explain why some patients continue to lose vision despite “good” pressure numbers.

Protecting your vision requires looking beyond the eye—and sometimes, that starts with how you sleep.