A dark room is the key to getting a good night's sleep, according to 73% of respondents in a National Sleep Foundation poll. It turns out that science agrees with popular opinion.

Even a dim artificial light (no brighter than a street lamp outside of a window) can cause a person to wake in the middle of the night, according to a peer-reviewed study published in Chronobiology International.

This isn't a case of "blue light" disrupting circadian rhythms (like using a smartphone before bed can do). No, researchers at Caltech believe that a protein in our brains responds directly to light exposure!

Can a "Blackout Eye Mask" Improve Sleep Quality?

A study published in Critical Care, a peer-reviewed medical journal, concludes that the "use of earplugs and eye masks in subjects not only improves subjective sleep quality, but also increases the amount of REM sleep and nocturnal melatonin levels."

To be fair, this study was conducted in a hospital setting where patients were exposed to light and sounds throughout the night, i.e. not your typical nighttime conditions. Nevertheless, an eye mask may be beneficial for those who are exposed to light during sleeping hours.

The best eye masks use natural, breathable materials and have an adjustable fit. Masks should be hand-washed as often as a pillow case to minimize the risk of developing acne or a stye (an eyelid infection).

Interestingly, eye masks are rumored to cause wrinkles. It sounds like nonsense, but some doctors believe that facial distortions during sleep (e.g. from too-tight a mask or sleeping face down on a pillow) can cause or deepen wrinkles. Consider speaking with your dermatologist if you plan to wear an eye mask regularly.

Are Weighted Sleep Masks Safe?

The risks of using a weighted sleep mask are likely to outweigh the potential benefits.

External ocular compression can result in intraocular pressure, which is likely to "contribute to significant ocular pathology, not only for glaucoma, but for retinal vascular occlusive diseases," according to a clinical study published in The Journal of Clinical Ophthalmology. In fact, even the simple act of pressing one's eyes into a pillow can increase intraocular pressure, according to an analysis published in Acta Ophthalmologica.

Weighted sleep masks are a relatively new product, and as a result, there are no clinical studies that directly speak to the risks of using one. However, a disturbing number of online reviews for these products mention "eye pain" and "blurry vision." I do not recommend these products.

How Much Does a Good Sleep Mask Cost?

A good sleep mask (with verified, above-average reviews) costs approximately $9, according to a 12-month analysis of price trends. Those same eye masks cost around $6 while on sale: an average discount of 33%.

Here are the best cheap blackout eye masks for the money:

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1. Bucky 40 Blinks Midnight Floral Eye Mask

Good Value: $11 | Great Deal: $9

Check Current Price on: Amazon | Walmart | Bed Bath & Beyond

Bucky's sleep masks are extremely comfortable because they leave room for eyelashes to blink, yet still manage to block out all light, according to several online customers. Some reviewers warn that the Velcro strap can catch hair; others say that the mask must be replaced every few years because its lining peels.

Note: This mask is also available in cool gray, hibiscus leaf, ruby pop and pink arabella.

2. Earth Therapeutics Rx3 Soft and Smooth Shut Eye Sleep Mask

Good Value: $10 | Great Deal: $7

Check Current Price on: Ulta | Bed Bath & Beyond

Earth Therapeutics' sleep mask is lightweight, comfortable and completely dark, according to several online customers. Some reviewers say the Velcro strap pulls on their hair; others say the mask has an odor.