If you or a loved one have glaucoma, there are eye health factors, such as how the disease can progress through the night and dangerous sleeping positions, that you should be aware of before heading to bed. Here, optometrist Shaun Larson, O.D. explains several night-related glaucoma concerns.*

Glaucoma progression at night

During the day, your eye makes and drains fluid continuously, but less fluid is made at night. Glaucoma prevents fluid from draining properly, leading to higher IOP and optic nerve damage. Even though both IOP and blood flow (to the head and eyes) generally decrease at night, IOP may not go down enough, increasing the risk for further optic nerve damage.

In fact, IOP can actually become elevated at night, due to:

• Changing body positioning during sleep
• Decreased eye fluid drainage
• Fluctuations in blood pressure and blood flow to the eye
• Reduced effectiveness of certain glaucoma medications at night

Fluctuations in IOP at any time, Larson explains, can strain the optic nerve head and ganglion cells of the retina that relay visual signals to the brain. This strain can lead to cell loss, glaucoma progression, and further vision loss.

It’s important, therefore, to regularly monitor your IOP (both daytime and nighttime), adhere to your prescribed medication regimens, and follow any doctor-advised lifestyle changes.

Why take glaucoma medications at night

Larson says glaucoma eye drops are typically taken at night to maximize effectiveness. Since IOP generally declines at night, the drops have more time to work as you sleep, which is especially important for those with higher IOP. At the same time, side effects that can interfere with daily activities can be avoided.

Not all glaucoma medications are taken at night, however. While some medications are typically taken once per day at night, like prostaglandin analogs (PGAs), other medications may need to be used multiple times a day.

Prostaglandin analogues

PGAs increase fluid drainage. These eye drops are typically taken once daily at bedtime. Examples of PGAs shown effective at slowing glaucoma progression include:

• Bimatoprost
• Latanoprost
• Travoprost

While all PGAs are “generally effective” at lowering IOP, Larson says, eye pressure reduction can vary between individuals. Some studies point to bimatoprost being slightly more effective at lowering IOP than latanoprost and travoprost. 

Your doctor will determine the most appropriate medication, since effectiveness can vary based on glaucoma type, glaucoma severity, underlying health conditions, and other medications.

Potential side effects include:

• Mild irritation
• Stinging or burning
• Iris color changes
• Eyelash darkening

Most people tolerate PGAs well, says Larson, and “the benefits of reducing IOP often outweigh the potential risks.” Proper eye drop use can help ensure their effectiveness.

Other glaucoma medications

In addition to PGAs, glaucoma medications often prescribed for daytime use may also be prescribed to be taken in the evening. These include:

• Beta-blockers and carbonic anhydrase inhibitors, which decrease eye fluid production, and
• Alpha-agonists, which decrease fluid production while also increasing fluid drainage.

Regular eye exams are essential for monitoring your glaucoma, ensuring that your medication is working effectively, and determining whether or not adjustments are needed.

Best sleep position for glaucoma patients

The best sleeping position to reduce IOP, Larson says, is lying on your side with the unaffected eye closest to the pillow. Conversely, IOP can increase by sleeping on your back or stomach.

Larson suggests speaking with your doctor about sleep strategies for managing IOP based on your specific needs.

*Larson, S. (n.d.). Why Take Glaucoma Eye Drops at Night? Low Vision Specialists. https://lowvisionaids.org/blog/why-take-glaucoma-eye-drops-at-night