Are blackout shades worth it?

Key takeaways

• They’re worth it if light is waking you or keeping you up. That usually means early summer sunrises, a streetlight outside the window, sleeping during the day after a night shift, or a child who wakes with the sun.

• Light at night affects the body even with your eyes shut. In a Northwestern University lab study, one night with the overhead light on raised sleepers’ heart rates and made them more insulin resistant the next morning.

• “Blackout” isn’t a regulated term. True blackout fabric blocks 99% to 100% of light, but many products sold as blackout are closer to room-darkening, and light leaks around the edges either way.

• They cost anywhere from about $10 to over $1,000 a window. A pair of budget blackout curtains costs less than a takeout dinner; custom cellular or motorized shades cost far more.

• A sleep mask does much of the same job for very little. It won’t help a baby or darken the room for a partner, but it travels and blocks light at the source.

The short answer

For a lot of people, yes. If your bedroom gets bright before you want to wake up, or never gets fully dark at night, blackout shades or curtains are one of the cheaper fixes in the bedroom, and they work every night without you having to do anything.

They’re less useful if your room is already dark, if you like waking with the daylight, or if you only need darkness for yourself and not the whole room. In those cases a sleep mask may be enough.

What light at night does to your body

Your body clock takes its main cue from light. Light in the evening and overnight tells it the day isn’t over, which can delay the release of melatonin, the hormone that rises as you get sleepy. In a 2011 study of 116 young adults, ordinary room light in the hours before bed delayed melatonin onset in almost every participant and cut the time melatonin was raised by about 90 minutes.

Light during sleep has effects of its own. In a 2022 Northwestern University study, 20 healthy young adults slept one night with an overhead light on (about 100 lux, roughly a dim room). Compared with people who slept in near darkness, their heart rates were higher through the night and their insulin resistance rose the next morning. Their melatonin levels didn’t change, so the effect seems to run through the nervous system rather than the hormone. It was one night and a small group, but the authors’ advice was simple: keep the bedroom dark.

Bigger studies have found links between bedroom light and health over time, though they can’t show cause and effect:

• Older adults in Chicago. Among 552 people aged 63 to 84 who wore light sensors for a week, the 54% who had any light during the darkest part of the night were more likely to have obesity, diabetes, or high blood pressure.

• Older adults in Japan. In a study of 863 people, those whose bedrooms averaged 5 lux or more at night were more likely to develop symptoms of depression over about two years than those with darker rooms.

None of this proves a streetlight will make you ill. People who are unwell may also turn lights on more at night. But a dark room is what sleep researchers recommend: a 2022 expert consensus says the bedroom should be “as dark as possible.”

How dark is dark?

Light is measured in lux. Most of what reaches a bedroom at night is surprisingly dim:

So a streetlight can easily put more light on your window than a full moon, and an early sunrise outshines both by a wide margin. That’s why summer mornings are often when people first think about blackout shades. In mid-June, the sun rises at about 5:06am in Boston and around 4:20am in Anchorage.

Who gets the most from blackout shades

Shift workers. If you sleep during the day, you’re up against full daylight, which is where blackout shades earn their cost. The CDC’s workplace safety institute tells day sleepers to make the bedroom so dark they can’t see a hand in front of their face, using blackout shades or drapes, or to wear an eye mask.

Early wakers in summer. If the sun reliably wakes you an hour before your alarm from May to August, blocking it is the simplest fix.

People near streetlights or signs. Ground-floor and city bedrooms often get the most outdoor light at night.

Kids. Many parents use blackout shades for children who wake at first light or nap during the day. Darkening a child’s room in the morning is also one of the standard tips for adjusting to the clock change.

People in the far north. In Alaska, where summer nights barely get dark, blackout curtains are common, and some people tape foil or cardboard over windows.

The case for some morning light

A completely dark room has a downside: it hides the morning. Morning daylight is the main signal that moves your body clock earlier, and the same expert consensus that calls for a dark bedroom also calls for bright light during the day. In a small 2013 camping study, a week of natural light and no electric light shifted people’s body clocks about two hours earlier.

If you struggle to wake up in a pitch-black room, open the shades as soon as you’re up, or get outside early. Some people use smart shades on a timer, or a wake-up light that brightens before the alarm. A small 2013 study of 17 people found that light rising gradually before waking improved mood and well-being in the morning.

Blackout vs. room-darkening

The two terms get used loosely, and there’s no industry standard behind either one.

• Blackout fabric is meant to block close to all light, 99% to 100%. It usually has a dense weave plus a coating or liner.

• Room-darkening fabric blocks most light but not all. Sellers quote anything from about 70% to 99%.

The fabric is only half of it. Light gets in around the edges: over the top of a curtain rod, down the sides of a shade, and under the bottom. A blackout shade mounted inside the window frame will still glow at the edges at sunrise. To get a room truly dark, cover the edges too:

• Hang curtains wide and high, so they overlap the wall on each side and above the window.

• Use a wraparound rod, which curves back to the wall at each end.

• Choose shades with side channels, tracks that hold the edges of the fabric.

• Layer a blackout curtain over a shade.

What they cost

Prices range widely:

These are rough ranges from retailers and cost guides, and prices for custom shades depend heavily on window size.

Other things blackout shades can do

Keep heat in or out. Cellular (honeycomb) shades trap air in their cells, which slows heat moving through the window. The Department of Energy found cellular shades cut heating energy by up to 20% compared with no shades. That comes from the cell structure and a tight fit, not from the blackout fabric itself. In summer, closed shades also block sun that would otherwise warm the room, which helps if your bedroom runs hot (our guide to the best temperature to sleep at covers the rest).

Block noise? Not much. Curtains sold as “soundproof” typically cut noise by only a few decibels, and they do little for the low rumble of traffic. If noise is the problem, earplugs, white noise, or better windows will do more.

A safety note on cords

Window covering cords are a strangulation risk for young children. The Consumer Product Safety Commission says about nine children under age 5 die each year from them. Under the industry’s voluntary safety standard, stock shades sold in the US since 2018 must be cordless or have short or inaccessible cords, and a 2022 revision, in effect since 2024, removed free-hanging cords from most custom products. In a child’s room, choose cordless or motorized shades, and keep cribs and beds away from any window with a cord.

Blackout shades or a sleep mask?

A sleep mask blocks light at the eyes for a few dollars, travels with you, and works in any room. There’s some evidence it helps. In a 2023 Cardiff University study of 94 young adults, a week of sleeping in an eye mask improved alertness and how well they learned new information the next day, compared with a week without one.

Shades make more sense when the whole room needs to be dark: for a child, for a partner who won’t wear a mask, for napping, or if you find masks uncomfortable. Many people use both, shades for most of the light and a mask for the leaks.

The verdict

Blackout shades are worth it if light is cutting your sleep short or keeping your room bright at night, and especially if you sleep during the day. Start cheap: a pair of blackout curtains on a wide rod, or a liner behind the curtains you have, fixes most bedrooms. Spend more on custom or motorized shades only if the cheap fix leaks too much light or you want them on a timer. If your room is already dark and you wake easily in the morning, you can skip them.

Frequently asked questions

Do blackout curtains block 100% of light?

Good blackout fabric blocks 99% to 100% of the light that hits it, but light still gets in around the edges. Hanging curtains wider and higher than the window, using a wraparound rod, or choosing shades with side channels gets you closer to full darkness.

What’s the difference between blackout and room-darkening?

Blackout fabric is meant to block nearly all light. Room-darkening fabric blocks most of it, anywhere from about 70% to 99% depending on the seller. Neither term is regulated, so check the stated percentage and look at reviews that mention light leaks.

Is it bad to sleep in complete darkness?

No. Sleep researchers recommend a bedroom that’s as dark as possible. The catch is waking up: morning light helps set your body clock, so open the shades or get outside soon after you wake.

Do blackout curtains keep a room cooler?

Somewhat. Closed shades or curtains block sunlight that would heat the room during the day, and insulating shades slow heat moving through the window. They won’t cool a room the way air conditioning or a fan does.

Do blackout curtains reduce noise?

Only a little. Even curtains sold as soundproof usually cut noise by a few decibels, and they do little against low traffic noise. Earplugs or a white noise machine will help more.

Should a baby’s room be completely dark?

A dark room helps babies and young children sleep, especially for daytime naps and early summer mornings. Pediatricians suggest a night light in the hallway rather than the bedroom if a child needs one. Use cordless shades in a child’s room.