Short answer: blue light filters can help a little, as part of an evening routine. Night mode and filter apps cut some of the blue light from one screen. Orange or red glasses filter almost all of it, from every light around you. None of them works as well as dimmer lights and putting screens down earlier, and the research on sleep is promising but still limited.
Why Blue Light Affects Sleep
Blue light is the short-wavelength part of visible light, roughly 380–500nm. The sun is by far the biggest source. During the day it helps keep you alert and your body clock on track.
In the evening, bright light, blue light especially, can delay melatonin, the hormone that helps signal it's time to sleep. A 2015 study in PNAS found that reading on a light-emitting e-reader before bed delayed melatonin and left people less alert the next morning than reading a printed book.
Types of Blue Light Filter
1. Night Mode (Built In)
Night Shift on iPhone and Mac, and Night Light or Eye Comfort on Android and Windows, warm the screen's colors in the evening. They're free and easy, but they only reduce blue light from that one screen.
2. Filter Apps
Apps such as f.lux shift your computer's screen toward warmer colors after sunset. Same idea as night mode, with more control.
3. Screen Filters
Physical films that stick onto a screen. They filter part of the blue light, but only on the device they're fitted to, and how much they filter varies.
4. Blue Light Glasses
Glasses filter everything you look at: your phone, TV, laptop and the lamps around you. For sleep, the lens needs to be orange or red. A clear lens lets most blue light through.
| Filter | What it covers | How much it cuts | Best for |
|---|---|---|---|
| Night mode | One screen | Some | Everyone, every evening |
| Filter app | One computer | Some, adjustable | Late laptop or desktop work |
| Screen filter | One device | Varies | A single device you use a lot |
| Orange or red glasses | Everything you look at | Almost all blue light | The last two to three hours before bed |
Do Blue Light Filters Help You Sleep?
The evidence is encouraging but small:
- In a 2017 study in Ophthalmic & Physiological Optics, 22 adults who wore blue-blocking glasses for three hours before bed for two weeks had about 58% higher nighttime melatonin.
- A small 2018 trial in the Journal of Psychiatric Research found modest sleep improvements in adults with insomnia symptoms who wore amber glasses for two hours before bed.
- A 2023 Cochrane review judged the evidence on blue light filtering lenses and sleep as uncertain, mostly because the studies are small.
Studies of night mode on its own have been mixed. How bright the screen is, and how long you stay on it, seem to matter as much as its color.
So think of filters as one part of winding down, not a sleep treatment. If you have ongoing trouble sleeping, talk to your doctor.
When to Use a Blue Light Filter
- Daytime: no filter needed. Daylight helps set your body clock.
- After sunset: turn on night mode and lower screen brightness.
- Two to three hours before bed: put on orange or red glasses and dim the lights.
- Bedtime: screens away, room dark.
Why Glasses Cover the Most
Night mode and apps only work on the screen they're running on. Evening light also comes from TVs, overhead LEDs and lamps. An orange or red lens filters all of it at once.
| Lens | Tint | Blue light blocked | Light let through (VLT) | When |
|---|---|---|---|---|
| SleepAid | Orange | 99% (380–550nm) | 48% | Evenings, before bed |
| SleepAidMax | Red | 99.7% (380–580nm) | 22% | Last hour or two before sleep |
Lab figures measured by Micro-Light Optics. UV400. Never drive in SleepAid or SleepAidMax lenses.
See our five best blue light blocking glasses for sleep.
Frequently Asked Questions
What does a blue light filter do?
It reduces the blue light reaching your eyes, either at the screen (night mode, apps, films) or at your eyes (glasses). In the evening, that can make light less likely to delay melatonin.
Are blue light glasses better than night mode?
They cover more: every screen and lamp, not just one device. Using both is fine.
Do blue light filters help during the day?
Not much. A 2023 Cochrane review found blue light filtering lenses probably make little or no difference to eye strain. Breaks, blinking and an eye exam help more.
How long before bed should I use a filter?
Two to three hours before bed for glasses, which is what most studies used. Night mode can go on at sunset.
The Bottom Line
Night mode is a free, easy start. Orange or red glasses cover every light source in the evening. Dimmer lights and putting the screen down earlier still matter most.
Read more: blue light and sleep quality · blue light glasses before bed
