Anyone sitting in a room at 60 years of age that appears pleasantly bright to a 20-year-old is actually seeing significantly less: according to estimates by the Lighting Research Center at Rensselaer Polytechnic Institute, with the same level of illumination, only about a third of the light reaches the retina of a 60-year-old compared to that of a 20-year-old. Those who want to know why older people need more light quickly encounter an underestimated figure: the pupil becomes smaller, the lens clouds over, and precisely the amount of light taken for granted becomes a scarce commodity in old age.
What really happens to the eye over the years
Two mechanisms are responsible for this, and both can now be well described. The first is so-called senile miosis: the pupil, which can open wide in the dark in young people, increasingly narrows over the years and also reacts more slowly to changes in light. A study published in 2024 in the journal Royal Society Open Science by Rafael Lazar, Johanna Degen, Anne-Sophie Fiechter, Alessandro Monticelli, and Manuel Spitschan (Max Planck Institute for Biological Cybernetics, Centre for Chronobiology at the University of Basel, and TU Munich) measured this systematically in everyday life for the first time across the entire lifespan, rather than just in a laboratory. The team followed participants between 18 and 87 years old with mobile measuring devices through their normal day and additionally under controlled laboratory conditions. The result: maximum pupil size decreases by about 0.4 millimeters per decade of life, a decline that adds up significantly over five or six decades.
The second mechanism concerns the lens of the eye itself. It is almost clear at birth but becomes thicker throughout life and increasingly deposits proteins, which make it appear slightly yellowish and cloudier. This has two consequences: overall, less light gets through, and the proportion of short-wave, bluish light is filtered out particularly strongly. As people age, they therefore not only see their environment as darker but also warmer and with less contrast, even if the eyes are otherwise healthy and no condition like cataracts is present.
One third of the light: what this estimate really means
The often-cited figure that a 60-year-old eye processes only about one third of the light volume that a 20-year-old eye uses under identical ambient brightness comes from the Lighting Research Center and is explicitly referred to there as an estimate, not the result of a single, precisely quantified study. This is important for context: it is a rule of thumb widely recognized in lighting research that results from a combination of pupil constriction, lens clouding, and altered retinal sensitivity, not a single measurement that could be read from one person. However, the general direction is well supported by numerous individual findings—such as the pupil study mentioned at the beginning. Reliable reporting should clearly distinguish between the two: a robust, repeatedly confirmed tendency on the one hand, and a rough guiding figure on the other.
For everyday life, this primarily means: the amount of light that seems sufficient to us at 25 can simply be too little for someone aged 65 or 75, without that person necessarily being consciously aware of it. Many older people grow accustomed to an environment that is too dark over the years, compensating unconsciously by leaning in closer, moving more slowly, or avoiding certain activities in the evening—and rarely attribute this to the lighting.
How much light experts recommend for older people
Together with the American senior organization AARP, the Lighting Research Center has developed concrete recommendations for interior spaces, which are regularly consulted by architects and lighting planners. The core message: ambient lighting for older people should be about 50 percent brighter than what younger people find comfortable, with a target value of at least around 300 lux. For activities with fine details or low contrast, such as reading, sewing, or working in the kitchen, about triple the amount of light is recommended, with a target value of at least 1,000 lux directly at the workspace.
Ambient light is not the same as task lighting
The distinction between two types of light is decisive here. Ambient light provides general orientation in a room, safety while walking, and a homely basic feeling. Task or activity lighting is placed specifically where the eyes have to work the hardest: above the work surface, at the reading chair, at the bathroom mirror. If only the general lighting is increased, the effect for fine tasks often remains minimal; if only selective brightening is used, safety is lacking in the transition areas in between, such as in the hallway or on the stairs. Good lighting design therefore always considers both levels together.
The study that shows: light changes how we walk
How strongly lighting actually affects the movement of older people was investigated by Mariana Figueiro, Barbara Plitnick, Mary Rea, Laura Gras, and Mark Rea in 2011 in the journal BMC Geriatrics. The study involved 24 adults aged 65 and over, half with a high risk of falling and half with a low risk, determined using the Berg Balance Scale and individual fall history. Each person walked through three light situations on a pressure-sensitive walkway: bright ceiling lighting with about 650 lux at corneal height, dim night light with only 0.015 lux, and the same night light supplemented by a laser line mounted on the floor that marked the path.
The results were clear: under bright lighting, the average stride length was 59 centimeters, whereas under the dim night light it was only 55 centimeters. Walking speed dropped from an average of 110 centimeters per second under good lighting to 101 centimeters per second in the dark, a statistically significant difference. The variability of stride length, an established indicator for fall risk, also increased in the dark. Particularly revealing: in the group with a high risk of falling, walking speed could be significantly improved again by the additional path marking, whereas this made almost no difference in the group with a low risk of falling. The authors themselves emphasize the limitations of their small sample size, but the core finding coincides with everyday experience: how safely someone moves in their own home depends visibly on the lighting, not just on strength or sense of balance.
Falls, independence, and the role of the environment
In its current factsheet, the World Health Organization (WHO) classifies falls as the second leading cause of fatal unintentional injuries worldwide, after traffic accidents. Every year, around 37.3 million falls worldwide are so severe that they require medical attention, and an estimated 684,000 people die annually from the consequences of a fall. The risk of a fatal or severely injuring fall increases continuously with age in all world regions. The WHO explicitly mentions unsafe living environments not adapted to an aging population as one of the central risk factors, alongside declining sense of balance and impaired vision.
A Cochrane review by Lindy Clemson and colleagues in 2023 summarized how effective it is to specifically reduce such environmental risks. The authors evaluated 22 studies with a total of 8,463 independently living older people, predominantly with an average age of 78, in ten countries. Among people with an increased risk of falling, for example after a previous fall or a hospital stay, a program for the professional identification and elimination of hazards in the home was able to reduce the number of falls by up to 38 percent. Poor or unfavorably placed lighting was one of the typically recorded hazards, alongside loose rugs, missing handrails, or slippery floors—however, the studies evaluated the entire package of measures and not lighting in isolation. For other measures such as pure education or individual aids, the review found no clear effect, an indication that it is the interplay of the environment as a whole that matters, not individual token measures.
Why our homes are often built for the eyes of 30 years ago
One reason why this topic remained in the background for so long lies in the history of lighting design itself. For decades, standards and recommendations for interior lighting were developed primarily with office and workplace situations in mind, i.e., with a comparatively young, working target group in mind. Living spaces were long considered secondary because fewer visually demanding activities supposedly take place there. The fact that visual ability changes so fundamentally over a lifetime only filtered into planning standards for private rooms very late.
At the same time, lighting technology itself has changed significantly: from the incandescent bulb to energy-saving lamps to today's LED technology, which now allows brightness and light color to be adjusted continuously at a comparatively low cost. This technical flexibility is new; it simply did not exist in this form a few decades ago. This means that many older homes are still equipped with the lighting logic of a time when neither today's findings on the aging eye nor today's technical possibilities were available. A lighting design that brings both together—knowledge about changed visual needs and today's technical means—is therefore less a question of taste than one that was simply not asked for a long time.
What good lighting actually means in old age
A few practical principles can be derived from lighting research that apply independently of individual products:
- More general brightness, evenly distributed: Dark corners and strong light-dark contrasts are harder for aging eyes to process than for young ones.
- Targeted light in the right places: Work surfaces, reading chairs, mirrors, and above all stairs and transition areas benefit from additional, permanently installed light.
- Avoid glare: More light is not automatically better; unshielded, very bright light sources can lead to short-term blindness due to glare in aging, more light-sensitive eyes rather than better vision.
- Warm, dimmable light colors in the evening: They support orientation without having the effect of harsh, cold light that is more reminiscent of clinical spaces.
- Pay special attention to transitions: According to the walking study by Figueiro and colleagues, hallways, stair steps, and the path to the toilet at night are the areas where light most strongly influences safety.
None of these principles require visibly "medical" or conspicuously technical solutions. On the contrary: good, well-thought-out lighting can be integrated into any interior without making a room look any less cozy.
Myths about light in old age
A few misunderstandings persist stubbornly around the topic of lighting and age. The biggest one: "The brighter, the better." In fact, lighting research shows that the right distribution and the avoidance of glare are what count, not the pure maximum brightness. A second common error is the assumption that poor vision in old age is fundamentally a question of eye health and can only be remedied by glasses or surgery. However, the described changes in the pupil and lens also affect people with perfectly healthy eyes and current glasses; they are a normal part of the aging process, not a disease. Thirdly, it is often underestimated how slowly and unnoticed the increased need for light creeps in: because the eyes adapt over years, many affected individuals do not notice themselves how much light they actually lack until a light situation suddenly appears significantly more pleasant by comparison.
From our perspective as a brand that deals with everyday objects for the second half of life, this very topic shows something fundamental: good design in everyday life is rarely a question of flashy technology, but often a question of whether anyone has even thought about the real needs of an aging target group.
Frequently asked questions
At what age does the need for light change noticeably?
The changes to the pupil and the lens of the eye begin gradually from about 40 years of age and then increase continuously. The 2024 Lazar study shows a decrease in maximum pupil size of about 0.4 millimeters per decade of life over the entire examined range of 18 to 87 years, without a clear tipping point.
Is it true that older people need three times as much light as younger people?
For fine, low-contrast activities, the Lighting Research Center in collaboration with the AARP indeed recommends about triple the amount of light compared to younger adults, with a target value of around 1,000 lux at the workspace. For general room lighting, the recommendation is lower, at about 50 percent more brightness than what is comfortable for younger people.
Can too little light actually increase the risk of falling?
The 2011 study by Figueiro and colleagues shows that stride length, walking speed, and gait variability measurably deteriorate in poor lighting, especially in people who are already at an increased risk of falling. The 2023 Cochrane review also confirms that the targeted elimination of hazards in the home, which includes lighting, can reduce the number of falls by up to 38 percent in at-risk individuals, albeit as part of an overall package of measures.
Is a brighter light bulb enough to make the home age-appropriate?
Not really. According to lighting research, the decisive factor is the interplay of sufficient, even general brightness, targeted light in work and transition areas, and the avoidance of glare. A single, very bright, unshielded light source can even worsen the situation.
Does this only affect people with eye diseases?
No. The described changes in pupil size and lens clouding are a normal part of the aging process and also affect people with perfectly healthy eyes. Conditions such as cataracts or age-related macular degeneration are additional factors for some people, but are a separate topic.
What distinguishes "good" from "clinical" light in the home?
Good lighting design for older people does not require cold, harsh, or conspicuously "medical" looking light sources. Warm, dimmable, glare-free, and specifically placed lighting fulfills the functional requirements without making a home look any less cozy or less private.
Sources
- Lazar, R. et al. (2024): Regulation of pupil size in natural vision across the human lifespan. Royal Society Open Science, Vol. 11, Issue 6.
- Max Planck Society: Pupil dilation decreases with age (press release on the study)
- Lighting Research Center / AARP: Lighting Principles for Older Adults
- Figueiro, M. G. et al. (2011): Lighting and perceptual cues: Effects on gait measures of older adults at high and low risk for falls. BMC Geriatrics, 11:49.
- World Health Organization: Falls – Fact Sheet (updated 2021)
- Clemson, L. et al. (2023): Environmental interventions for preventing falls in older people living in the community. Cochrane Database of Systematic Reviews, CD013258.
