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Is Red Light Good for Sleep?
- Exposure to light plays a major role in regulating circadian rhythm, your body’s sleep-wake cycle.
- Red light therapy may support sleep quality and improve sleep inertia (grogginess upon waking), though more research is needed.
- Blue light can suppress melatonin and disrupt sleep, so avoid electronics before bedtime.
It’s common knowledge that bright lights (and the blue glow of laptops, TVs, and cellphones) before bed can sabotage sleep. But not all types of light are bad for rest. On the contrary, red light shows some promise for positively impacting sleep.
Below, we’ll discuss how red light affects your body’s natural sleep-wake cycle and how to use it to optimize your sleep routine.
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How Does Light Affect Your Sleep?
Light plays a major role in regulating sleep, as it controls your circadian rhythm, or the body’s internal clock that dictates your sleep-wake schedule. In nature, this rhythm follows the sun — you wake up with sunrise and feel sleepy after sunset.
“In the morning, natural sunlight (especially blue light) hits your eyes and signals the brain to stop producing the sleep hormone [melatonin],” says Praveen Rudraraju, MD, medical director of the Center for Sleep Medicine at Northwell’s Northern Westchester and Phelps hospitals. “This increases alertness, boosts mood, and helps set your circadian rhythm so you feel sleepy at the right time later.”At night, when it gets dark, your brain starts preparing for sleep.
However, in the modern world, artificial light, especially from screens, keeps sending “daytime” signals to the brain. Blue light is high-energy light that strongly suppresses melatonin and activates the brain, making it harder to fall asleep and stay asleep. Light exposure in the evening can also alter the different stages and cycles of sleep that a person experiences during the night, known as sleep architecture.
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What Is Red Light Therapy?
Red light is on the visible light spectrum, i.e., the wavelengths of light the human eye can detect. Of all the visible colors, it boasts the longest wavelength, measuring approximately 700 nanometers.
Research has shown different wavelengths of light can produce certain physiological effects in humans. Red light is a prime example. It can penetrate human tissues and trigger changes on a cellular level including:
- Increased mitochondrial production of adenosine triphosphate (ATP), a main source of energy in cells
- Improved cell repair and growth
- Reduced oxidative stress
Given its potential benefits, red light has been used as a therapy for a range of health conditions including wound healing, pain, chronic inflammation, and skin problems. Scientists are also studying whether it can be therapeutic for sleep.
Is Red Light Good for Sleep?
While the science is still evolving, current data appears to suggest that red light therapy may help with sleep. The mechanism isn’t fully understood, but red light appears to have a few characteristics that make it supportive of sleep.
Firstly, red light seems to have a different effect on intrinsically photosensitive retinal ganglion cells (ipRGCs) than other types of light. These specialized cells in the retina contain a photopigment that makes them sensitive to light, which is why they play a critical part in regulating the body’s circadian rhythms. For example, when they detect blue light, the body gets the message that it’s time to wake up.
Compared to blue light, ipRGCs appear to be much less sensitive to red light. Additionally, “red light doesn’t strongly suppress melatonin like blue light does,” says Dr. Rudraraju. This is important, because melatonin plays a pivotal role in inducing sleepiness. So, red light before bed doesn’t confuse your body clock like blue light does, making it a safe choice at night.
Sleep Quality
In fact, red light before bed may help you sleep more soundly. “Some studies suggest exposure to red light in the evening can encourage natural melatonin production, which can help with sleep,” says Dr. Rudraraju. One Chinese study found that 30 minutes of red-light therapy every night for two weeks improved sleep quality, melatonin levels, and endurance in female athletes.
Red (and near-infrared) light therapy may also have potential benefits for insomnia, says Laxminarayan Prabhakar, MD, a sleep medicine physician at Northwell.
Sleep Inertia
“Sleep inertia is the first half hour after waking up where the body is still in the sleep mode and not fully awake,” Dr. Rudraraju says. Though the groggy feeling typically lasts 30 minutes, it can linger longer (especially if a person is sleep deprived) and temporarily impair mood, memory, and thinking.
Some research suggests that red light before bed may improve alertness upon awakening, especially for night shift workers. One study concluded exposure to saturated red light through special goggles helped people feel less tired and disoriented upon waking.
However, research is still in the early stages, and more quality studies are needed to determine whether red light therapy is an effective treatment option for sleep inertia, he adds.
“Morning sunlight or blue light exposure is still the best way to fully wake up,” says Dr. Rudraraju.
Night Vision
Red light may also help you see better at night. Your eyes produce rhodopsin, a chemical that lets you see in low-light conditions. As soon as the eyes are exposed to bright light, rhodopsin breaks down, and night vision fades. Red light doesn’t break down rhodopsin, so night vision is maintained.
This use of red light differs from red light therapy. For night vision, you don’t need a therapeutic grade red light, but rather light bulbs with a red tint or red gels. Even covering a flashlight with red cellophane or painting its lens with a red magic marker will have the desired effect.
How Do You Use Red Light for Better Sleep?
Though research is still in the early days, it appears red light may be a useful tool for sleep. Many at-home red-light devices are available if you want to try it for yourself.
Here’s how to use red light safely for better sleep:
- Pick the right device: Look for products that are FDA-cleared to ensure safety. The light should emit 660 to 870 nm wavelengths, which match those used in research.
- Timing matters: Use red light for 30 minutes, three times per week, one to two hours before bed, says Dr. Prabhakar. Try it for a month, then assess whether your sleep has improved. Alternatively, you can also use the red light nightly for 14 days, he says.
- Keep it dim: Keep the intensity at or below 10 lux. If the light is too bright, it can still disrupt sleep, says Dr. Prabhakar.
What Else Can You Do to Improve Sleep Quality?
While red light therapy shows some promise for sleep, it’s not a magic pill or replacement for healthy sleep habits, says. For the best results, red light still has to be combined with sleep hygiene tactics.
Here are Dr. Rudraraju’s top tips:
- Avoid blue light sources an hour or so before bedtime. Put away phones, tablets, and laptops if possible.
- Sleep in total darkness. Use blackout curtains in the bedroom to prevent early waking from morning light, especially during summer.
- Keep the bedroom cool. The ideal bedroom temperature falls between 60 and 68 degrees Fahrenheit.
- Get natural sunlight in the morning. This helps set your circadian rhythm so you feel sleepy later in the evening.
Frequently Asked Questions
Is it good to sleep with a red light on?
“No, red light, and any other light sources, should be turned off to sleep,” says Dr. Rudraraju. While red light exposure before sleep may be beneficial, it can have the opposite effect when used during sleep. “Continuous exposure may increase microarousals and negatively affect sleep architecture and mood,” Dr. Prabhakar says.
For better shuteye, shut off all the lights and sleep in total darkness.
What light color is best for sleep?
Red light doesn’t suppress melatonin production very much and may have positive effects on sleep, Dr. Rudraraju says. That said, red light can still negatively impact sleep when used at a high intensity, says Dr. Prabhakar. Green light (at wavelengths around 530 nm) may also help promote sleep, he adds.
What color light should you avoid at night?
If you want to get a good night’s rest, steer clear of blue light, which can disrupt circadian rhythm. “Blue light (∼470 nm) is particularly alerting, delays sleep onset, and elevates arousal markers such as corticosterone in animal models,” Dr. Prabhakar says.
Blue light’s anti-sleep effects likely relate to its suppression of the sleep-promoting hormone melatonin, Dr. Rudraraju says.
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