Is turning your phone to red light the secret to better sleep?

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For some people, scrolling in bed is the only ‘me time’ they get in a day. But doomscrolling at night may be keeping your mind awake while your body is tired, disrupting your body clock and leading to poor night’s sleep.

If you’re looking for some way to make doomscrolling less appealing and, in turn, improve your sleep quality, there's a hack for that. It turns out, using a filter in your phone settings to turn your screen red can reduce the blue light that keeps you up at night while also making the visuals you see lose their lustre. But how and why does it work? We spoke to experts to find out.

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Red light vs blue light – which is better for helping you wind down?

We all know we should avoid bright light before bed, but it turns out that some colours of light may disrupt your sleep more than others.

Melatonin is a hormone that largely controls your body’s natural sleep-wake cycles. Specialised photoreceptors in your eyes send information back to your brain and influence your production of melatonin. This research review has found that these receptors are most sensitive to light with wavelengths around 450 to 480 nanometres (nm). To most people, this light appears blue.

There’s still a limited amount of research looking at the effects of other light colours on our sleep cycles. However, there’s some evidence that warm colours, like the colours we see at sunset, may help lull you to sleep more quickly than cool colours.

Dr Maria Knöbel, medical director and co-founder of Medical Cert UK says, ‘The blue light that phones emit disrupts melatonin and pushes back sleep onset, which helps explain why so many of us feel compelled to stay up late and wake up tired.’

Red light does not affect circadian rhythms, so it is one of the best lights to use at night. Research has shown that exposure to red light can improve sleep and increase the production of melatonin.

Dr Emma Lin, a pulmonary and sleep physician says, ‘I’ve witnessed patients wearing a red-light filter on their phones dose off more rapidly, sleep more soundly, and wake up more refreshed.’

How a red light filter may help stop doomscrolling

Dr Lin says, ‘Turning your phone screen dark red means that if you’re looking at image-based apps like Instagram or TikTok, you won’t be able to view colours properly, and it will make the app less appealing. You will still be able to view text, so have the ability to read, but patients I have worked with found that they stopped using Instagram at night, having previously spent hours on the app before bed, purely because they weren’t able to view images properly.’

Physician Dr Naheed Ali agrees that the warm tone also helps reduce doomscrolling. ‘Bright, cool light keeps the nervous system switched on and pairs with fast content to create a cycle of novelty seeking. A red-light filter slows this pattern. The phone becomes less gripping and more purposeful, which makes it easier to close apps, put the device down, and return to real wind-down habits like reading, stretching, or breath work. The mind gets an unhurried runway into sleep, and the stress response has fewer spikes before bed.’

Red light filter and cortisol

Cortisol, a stress hormone, is also affected by insufficient sleep, and using your phone may exacerbate this issue. Dr Knöbel says, ‘Blue light has such a strong stimulating effect on us that continuous exposure keeps cortisol levels 15-20% higher than they would normally be. When you look at light with a wavelength of around 480 nanometers, you get a much more potent kick of stimulation, which means your body's not going to quiet down and get ready for rest anytime soon.’

Dr Knöbel continues, ‘Whereas red light tends to have nothing but calming effects on the body's cells, blue light has the exact opposite effect. So, if you can't stop using your phone before bed, at least do it under a red filter, and then see how much better it makes you feel.’

Having a red light in the bedroom also helps you feel calmer at night. A quality improvement project examined the impact of changing the lights from white to red at an old age psychiatry ward. The researchers administered a staff questionnaire, and the results showed that patients were less agitated at night and slept better under the red light condition.

Does a red filter on your phone improve your vision?

Red light filters on phones don't correct vision problems or enhance visual acuity. However, they can provide some benefits for eye comfort, particularly in certain situations, according to Dr Taj Nasser, medical director of Tylock Eye Care.

Potential benefits of red filters (or red light modes) include:

• Reduced eye strain in dark environments - red light is less disruptive to your night vision and doesn't cause your pupils to constrict as much as blue or white light
• Reduced glare sensitivity - some people find red-filtered screens more comfortable in low-light conditions

Dr Nasser says, ‘Most phones now have ‘night mode’ or ‘blue light filter’ settings that shift the display toward warmer colours (more red/orange, less blue) rather than pure red filters. These are generally more practical for daily use while still providing some of the eye comfort benefits.’

Suppose you're experiencing eye strain from using your phone. In that case, other strategies, such as taking regular breaks, adjusting screen brightness, maintaining proper distance, and ensuring good ambient lighting, are typically more effective than relying solely on colour filters.

Will a red light filter help me sleep better?

Sleep specialists say rather than worry about the light itself, focus on how you’re using screens - whether they’re calming or activating. Avoid using screens in bed to maintain the strongest association between bed and sleep. 

‘It’s not just about the colour of the light - it’s about creating calming, consistent habits so your brain learns to associate bedtime with feeling safe, not alert. If your bedtime routine includes scrolling, it’s essential to be mindful of the emotional impact, not just the lighting,’ advises specialist sleep psychotherapist Heather Darwall-Smith.

Darwall-Smith says, ‘Using the red-light filter on your phone at night can feel like a clever workaround to use your phone in bed. The idea makes sense: there has been a lot of noise about how blue light from screens tells your body clock it’s still daytime, while red light has marginally less of that effect. So yes, the red glow is definitely gentler on your sleep biology. The bigger issue is the behaviour that keeps you scrolling and delays bedtime.’

‘Sucked into the doomscroll loop your brain stays switched on,’ says Darwall-Smith. ‘Red light won't stop that from happening, your brain still lights up at emotional or anxiety-fuelled content – that’s the ‘doomscrolling effect’ – that keeps you awake. On top of that if your bedtime routine is still tied to scrolling, your brain learns that bed = stimulation, not rest. There is no red light that can break that link.’

‘Think of using red light as a helpful stepping stone, not a magic fix because it can be more stressful to go cold turkey on screen use. If you want to really protect your sleep, pairing the red filter with a cut-off time for screens (or swapping doomscrolling for a gentler wind-down like music, journaling, or a book) is where the real difference shows up. Also keeping regular sleep–wake times and ensuring sufficient exposure to natural light during the day to support your circadian rhythm – establishing solid habits is far more useful than relying on a red filter,’ says Darwall-Smith.

To create a relaxing bedtime routine, Darwall-Smith suggests:

• Reserving an hour before bedtime to wind down away from stressful, stimulating activities. Relaxing steps and rituals like these make it easier to fall asleep:
• Putting away electronic devices, except if used for calming music or a guided relaxation routine.
• Reading for pleasure in soft light.
• Taking a warm bath.
• Doing some easy stretches, progressive muscle relaxation, or deep breathing.

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