Lighting
Bringing daylight into the home is very important. As our eyes age,
less light actually gets to the retina to stimulate the nerves, therefore,
more light (without glare) is required. The intensity of daylight is
much greater than typical electric lights and daylight includes the full
color spectrum. Furthermore,
as natural daylight is free, there are significant economic and physical
reasons to include the principles of "daylighting design" into
your home.
Appropriate design criteria will vary depending upon your
geographic location so it is best to contact a local lighting designer
or architect who specializes in "daylighting design".
The
most successful solutions bring the daylight into a space above the field
of view through diffused glazing material. Rays of sunlight through
clear glass or plastic can produce both unwanted glare and shadows.
Older eyes benefit from the increased quantity and quality
of light
Quantity
 Ambient
(general) illumination should be about three to four times higher than
is typical for young people. 30 footcandles is recommended for general
room lighting. Light levels should be adjustable by switching on a dimmer
to allow adjustments according to the seasons and time of day. Bedroom
and bathroom areas should have separate lighting for day and night; high
during the day and low at night. Every room, including the living room
and family room, should have built-in lighting with control switches
at each location where people enter or exit a room. Motion sensors may
be used so that lights come on only when rooms are occupied. Table and
floor lamps should be used in combination with built-in general illumination.
Quality of Light
- Light levels that are adequate for the visual task
- Glare avoidance (direct and reflected)
- Uniformity in general lighting (with areas of interest that are
not dramatically different)
- Orientation of lighting to the visual task
- Reduction of visual busyness
- Good color rendering
- Location and directional considerations to prevent accidents
- Balanced daylight and interior ambient light.
- Walls and floor areas evenly illuminated
As we age, our eyes become much more sensitive to glare. The highest
rate of increased glare sensitivity occurs after the age of sixty.
There are two types of glare: 1) direct glare, bright light from a
fixture or bright sunlight streaming into a dimly lit room; and 2)
reflected glare, strong light that bounces of a smooth shiny surface.
Avoiding Direct Glare
The best way to avoid direct glare is
to utilize indirect lighting. This is accomplished by using a concealed
light source where light is directed toward a ceiling or wall and reflected
back into the room. It is important that the surface of the ceiling
or wall be a matte finish and light in color. Exposed bulbs such as
the tiny lights on a chandelier will produce direct glare and should
be fitted with a translucent shade. Sheer draperies or woven shades
should be used to minimize the glare and yet allow daylight into the
room.
Avoiding Reflective Glare
Problem areas include glass-top tables,
highly polished floors and/or counters and light-colored sidewalks.
Reflected glare can be avoided by using materials with a matte finish
or colors with a medium value. However, the kitchen presents
a real challenge at the sink and the stove. Porcelain reflects less
glare than stainless steel, but these surfaces are not trouble free.
Rubber mats in the sink will help to reduce some of the problem.
  Providing
Task Lighting
Consideration should be given to increased
light levels in areas for reading, hobbies, and daily activities. In
the kitchen, lights located under the upper cabinets are essential
for providing light on the work surface. For vanities,
fixtures located on each side of the mirror that illuminate both sides
of the face for shaving and applying make-up are important. Closet
areas require light that does not alter the color of the clothing and
is sufficient to distinguish dark colors (i.e. navy and black). Light
sources have a color rendering index (CRI) which rates them on a percentage
scale (high numbers being the best) for how true a color will appear
under that light source. Sources rated 80 or above are recommended.
Lighting can also improve your general health
Light Exposure
In addition to providing light for vision, the photobiological effects
of light are very important for the health of older people.
- Sunlight on the skin produces vitamin D, which is required for
calcium to be absorbed and keep bones strong. One
study of older persons living at home found that 54% had low vitamin
D levels (Gloth FM, et al. Vitamin D deficiency in homebound
elderly persons JAMA 1995; 274:1683-6).
- Daylight through the eyes keeps our body clock (circadian rhythm)
synchronized with the day/night cycle of light. Circadian rhythm
disruption impacts both sleep at night and alertness during the day.
A high percentage of older people experience sleep disorders due
in part to lack of daylight.
Sunlight on the Skin
Calcium and vitamin D are essential to
maintaining healthy bones through out life. Osteoporosis, the
most common disease of the bones, characterized by a decrease in bone
mass and density, is often called the silent epidemic. Worldwide osteoporosis
afflicts an estimated one-third of women aged 60 to 70, and two-thirds
of women aged 80 or older. Vitamin D deficiency can be prevented
by sun exposure. A Japanese study of 258 stroke patients 65+ years
old, half of which were exposed to sunlight on their face and hands
for 15 minutes per day for a year, and half (control group) of whom
maintained their normal activities without any specific activity for
sunlight exposure, found that hip fractures significantly decreased by
84% in the sunlight-exposed group. Also, bone mineral density
increased by 3.1% in the sunlight-exposed group, and decreased 3.3%
in the control group (Sato Y, Metoki N, Iwamoto J and Satoh K. Amelioration
of osteoporosis and hypovitaminosis D by sunlight exposure in stroke
patients. Neurology 2003; 61:338-342). Most window glass
blocks the ultraviolet light need for vitamin D synthesis, so plan
to go outdoors without sunscreen, make-up, or lotions which might include
sunscreen, for 15 minutes per day exposing the face and hands. It
is best to avoid the two hours before or after 12:00 noon.
Light Through the Eyes
Recent discoveries of the specific
cells in the retina of the eye that relay information to our body clock
and the particular wavelength (similar to the blue sky) to which these
cell are most sensitive reinforces the recommendation for including
daylight within homes and encouraging people to spend time outdoors.
 For
more specific information about making lighting modifications to an
existing residence, please go to: Lighting
Your Way to Better Vision.
For more information about Light for Health, please
review "Proceedings of the 2nd CIE expert Symposium on Light and
Health." http://www.cie.co.at/index_ie.html
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Center
of Design for an Aging Society