Brighter is not always better.
Most lighting advice for older eyes amounts to "turn the lamps up." There's truth in there, but it skips half the picture. The wrong kind of light in the wrong place makes a page or screen harder to read no matter how many watts you throw at it. The right kind, even at modest levels, can make 20/20 eyes feel effortless and reduced contrast sensitivity easier to live with.
This is a practical guide to lighting your home and workspace for contrast. Aimed at anyone over 40 who finds reading harder than it used to be, or whose room lighting is making them squint. The physics lives in the cross-links; what we cover here is the decision tree — what to measure, buy, skip, and where to put it.
Why lighting and contrast are the same conversation
Three things move together when you turn the lights up. Your pupil contracts — a smaller pupil is a better optical instrument, with fewer peripheral aberrations reaching the retina (longer treatment in our low-light post; the same eye is a different optical instrument at a 3 mm vs a 6 mm pupil). Your photon signal climbs — noise grows as the square root of photon count, so doubling the light improves signal-to-noise and fine detail gets through. Your adaptation point stabilises — contrast is the difference between dark and light, not the absolute brightness of either, and a page lit well with no harsh source in your field of view lets ink and paper register fully.
So the goal is not just "more lumens." It is high overall ambient light, with no direct glare into the eye, on a page whose contrast is not being washed out by stray light. Get those right and a normal eye reads effortlessly; get them wrong and even a clean optical system fights the room.
The age-related layer is real. The IES Recommended Practice RP-28 — the standard reference for lighting older adults — assumes adults over 65 need roughly twice the light levels recommended for the 25-65 band for the same visual performance. The mechanism is partly senile miosis, partly intraocular scatter, partly the age-related decline in contrast sensitivity (Owsley, Sekuler & Siemsen, 1983; Mäntyjärvi & Laitinen, 2001). A lamp that was plenty in your thirties may be underpowered in your sixties. Biology, not failure.
The five questions for your task lighting
1. Brightness (lux). Lux is illuminance — the light hitting a surface, in lumens per square metre. Most homes run living and reading spaces at 100-300 lux. The IES recommends roughly 300-500 lux for general reading, 500-750 for difficult or sustained reading, and the upper end — or higher — for older adults. A $15 lux meter or a phone app gives you a usable number: put the phone on the page, screen up. If it says 100, you have a problem; 400 is roughly where general reading wants to be; over 60 and still effortful at 400, push to 600-800.
2. Position. A reading lamp belongs above and slightly behind your reading shoulder, aimed at the page. The classic mistake is putting the lamp in front of you so the light arc passes through your field of view and into your eye — pulling effective contrast on the page down via the veiling-luminance mechanism. If you can see the bulb directly without turning your head, it's in the wrong place.
3. Color temperature (Kelvin). Candle is ~2000 K, old incandescent is 2700 K, crisp daylight is 5000-6500 K. 4000-5000 K works well for sustained daytime reading and detail work; warmer light (2700-3000 K) is more comfortable for evening reading and supports better sleep. The melanopic-EDI consensus from 18 circadian researchers in PLOS Biology recommends at least ~250 melanopic EDI by day and significantly less in the evening — a useful translation of "cool by day, warm by night" into a number (Brown et al., 2022). If a single light has to do all your reading, 3500-4000 K is a safe default.
4. CRI (color rendering index). A 0-100 number describing how faithfully a light source renders colors compared with sunlight. 80 is the consumer LED baseline; 90+ is what professional artists and photographers use. Cheap LEDs at 70-80 wash out subtle color and contrast. Aim for CRI 90+. It's printed on the box; the premium is a few dollars per bulb, and the upgrade is consistently noticeable.
5. Flicker. The one nobody talks about, and the one that quietly explains a lot of "my new lights give me eye strain" complaints. Cheap LEDs rectify mains AC with simple drivers, so the light flickers at twice the mains frequency — 100 Hz in Europe, 120 Hz in the US. People often can't consciously see flicker that fast, but the visual system detects it, and a body of work links sub-perceptual flicker to eye strain, headaches and reduced visual comfort over hours (Bullough et al., 2011). IEEE 1789 sets a recommended-practice threshold for low-risk flicker that better-quality bulbs meet and cheap ones often don't.
Practical test: open the phone camera, point it at the lit bulb, and slowly pan. Horizontal banding moving through the frame means the bulb is flickering visibly to the sensor — and to your visual system, even if your conscious eye can't catch it.
What warm vs cool actually does
Cooler light is shifted toward blue, which activates the intrinsically photosensitive retinal ganglion cells (ipRGCs) that drive alertness and circadian timing. A cooler bulb at noon helps you stay sharp; the same bulb at 10 pm pushes sleep onset later (reasons in the screens-at-night post) and slightly enhances perceived contrast on text.
Warmer light activates ipRGCs less, interferes less with sleep at night, and slightly compresses perceived contrast. If you do both day and evening reading, install dimmable, color-tunable bulbs — most "smart bulbs" do the cool-to-warm transition automatically once you set the schedule.
What to buy, what to skip
We deliberately don't name brands — what matters is the spec on the box, not the logo on it.
Skip $3 LED bulbs from discount bins. CRI in the high 70s, no published flicker spec, short life.
Skip harsh single-source desk lamps that point a bright disc into your field of view, especially the cheap clip-on kind whose hood is too small to control glare.
Skip "daylight" tube fluorescents in workspaces where you'll sit for hours. Well-documented flicker, mediocre CRI.
Buy bulbs labelled CRI 90+ (sometimes "high CRI" or "Ra 90"). Most major manufacturers sell a high-CRI line at modest premium.
Buy dimmable lamps with bulbs that genuinely dim well. Cheap dimmable LEDs flicker more visibly when dimmed; better ones don't. Dim to ~30% and run the phone-camera-banding test before committing.
Consider a daytime task lamp at 5000 K CRI 95+ for detail work like sewing, model-making, or photographs. These exist for the art and dental markets and are unreasonably good for everyday tasks.
Set up two or three diffuse lights in a room rather than one bright one. Multiple sources reduce harsh shadows and produce more uniform illuminance.
Screen-specific guidance
The screen is itself a light source, which adds constraints.
Match ambient light to screen brightness. A bright screen in a dark room is a contrast mismatch — the eye adapts to the dim surround while looking at a bright stimulus, and low-contrast UI elements get washed out. A dim screen in a sunlit room is overpowered by reflections. The screen should look like it belongs in the room.
Reorient to keep window glare off the screen. Failing that, anti-reflective film, a matte monitor, or a curtain.
Use warm-screen modes after sunset (mechanism in the screens-at-night post).
Turn the screen down for long sessions. 400 cd/m² is outdoor-laptop brightness; 80-150 cd/m² indoors is typical for sustained comfort.
For older eyes specifically
If you are over 60, every decision above tilts the same direction: more light, more glare control, more attention to flicker. The combined effect of senile miosis, intraocular scatter and the normative age-related contrast decline means an older eye reaches the retina with meaningfully less usable light than a younger eye in the same room. Home-lighting surveys of older adults consistently find median household lighting well below clinical-task recommendations. Many "I can't read like I used to" reports are partly a lighting problem masquerading as a vision problem.
This is not weakness and not always disease — it is optics plus physiology. The trio that makes daily reading feel easy past 60 is brighter ambient light, well-placed task lighting, and a correct, recent prescription. Each leg compensates partially for what the others can't do alone.
What our test can tell you (and what it can't)
Note. Take the contrast sensitivity test under normal indoor reading lighting — a quiet, well-lit room, not bright sun, not a dim hallway. The result is a snapshot of your photopic contrast sensitivity, related to but not identical to your day-to-day reading experience. A normal result does not guarantee comfortable reading; a reduced one does not mean your room is the problem. Test-retest noise on calibrated contrast sensitivity testing is roughly ±0.15 log units, so a short-term improvement from a new lamp probably won't show up as a new CSF number, even when daily reading feels easier.
If your CSF is normal and reading still feels effortful, lighting and ergonomics are usually the highest-leverage thing to change — the test rules out one mechanism, and the answer is in the room. If your CSF is below typical for your age, better lighting won't move the biology, but it reduces the daily load on the part of vision doing less. Both groups benefit from the room being right.
Practical next steps
- Measure the room. Lux meter or phone app, on the page, in every spot you read or work. Note where you are below 300 lux.
- Replace the worst three bulbs with CRI 90+, low-flicker bulbs in a color temperature matched to when you use them.
- Move one lamp. Any reading lamp in front of you instead of behind your shoulder — move it. Free, and often the single biggest improvement.
- Take the test as a baseline, then improve the room. If reading comfort changes, the room was a big part of the story. If reading still feels effortful with the room dialled in, that's a different conversation to have with your eye doctor, number in hand.
Take the test
Take the free test. Three minutes, then improve the room. Many people see meaningful gains in daily comfort from lighting alone — and the ones who don't have a clearer reason to bring it to a clinician.
Brighter is not always better. Right is better. And "right" is mostly cheap, mostly DIY, and within your control.
References
- Pelli, D. G., Robson, J. G., & Wilkins, A. J. (1988). The design of a new letter chart for measuring contrast sensitivity. Clinical Vision Sciences, 2, 187–199. Methodology anchor for clinical contrast sensitivity and the standard reference for test-retest variance (≈0.15 log units).
- Owsley, C., Sekuler, R., & Siemsen, D. (1983). Contrast sensitivity throughout adulthood. Vision Research, 23(7), 689–699. Foundational study; basis for the roughly 10%-per-decade age-related decline.
- Mäntyjärvi, M., & Laitinen, T. (2001). Normal values for the Pelli-Robson contrast sensitivity test. Journal of Cataract and Refractive Surgery, 27(2), 261–266. Age-stratified normative Pelli-Robson values used clinically as the reference band for "typical for your age."
- Brown, T. M., Brainard, G. C., Cajochen, C., Czeisler, C. A., Hanifin, J. P., Lockley, S. W., et al. (2022). Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLOS Biology, 20(3), e3001571. Consensus recommendations from 18 circadian researchers, expressed in melanopic equivalent daylight illuminance — basis for "cool by day, warm by night."
- Bullough, J. D., Sweater Hickcox, K., Klein, T. R., & Narendran, N. (2011). Effects of flicker characteristics from solid-state lighting on detection, acceptability and comfort. Lighting Research & Technology, 43(3), 337–348. Empirical evaluation of LED flicker; basis for the flicker-free guidance.
Standards (not peer-reviewed)
- Illuminating Engineering Society. (2020). ANSI/IES RP-28-20: Recommended Practice — Lighting and the Visual Environment for Older Adults and the Visually Impaired. Source for the recommendation that adults over 65 typically need roughly twice the light levels of younger adults.
- IEEE Power Electronics Society. (2015). IEEE Std 1789-2015: Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers. The recommended-practice threshold for low-risk flicker.