electric lights don’t usually send the right cues to keep
our daily rhythms in check. The results go beyond just
feeling a bit out of sorts – poor lighting can contribute
to depression, low productivity, weight gain, and can
increase the risk of other health problems or exacerbate
those we already have. Studies have shown that hospital
patients in sunnier rooms experience less stress, use less
pain medication and don’t stay as long.
In the Russian spacecraft, the fluorescent lighting
lacked the blue element in daylight that our body clocks
rely on. Nasa is now spending more than $11 million
(£ 7 million) replacing fluorescent lighting on the
International Space Station with LEDs, so it can control
the colour, intensity and timing of lighting to help
astronauts sleep better and awake refreshed.
It is a happy coincidence that our understanding of the
biological effects of light has blossomed at the same
time that LEDs and lighting controls have taken off
– technologies that let us harness this knowledge by
tuning the colour and intensity of light during the day
to match our circadian rhythms. Companies including
Philips, Osram and Fagerhult have contributed to
extensive research in this area, coming up with dynamic
lighting solutions for schools, offices, homes, hospitals
UK LED lighting specialist PhotonStar recently secured
a $2 million (£1.3 million) investment to develop
biodynamic lighting products including wireless
controllable lamps, building on its colour-tuning
technology. PhotonStar’s Fenella Frost says the priorities
of lighting manufacturers and designers are changing.
‘First it was all about safety and practicality, then it was
all about energy, then it was about sustainability,’ she
says. ‘To me the next level is about human health and
productivity. By installing energy-efficient lighting you
might be able to save 40 per cent of your energy, but if
you can improve the productivity of the people in there
by just one per cent, that’s a much bigger number. The
potential is absolutely huge.’
She believes the applications are ‘incredibly broad’.
‘Any area where people spend time, we have the
opportunity to provide more human-centred lighting.
Whether that’s a home or a retailer trying to get you to
buy a particular product – these are all target markets.
Anywhere where people spend time and the owner has
an interest in the health and wellbeing of the occupants
– schools, prisons, hospitals, shops homes… It’s going
to become something that isn’t much more expensive
than standard lighting.’
Piergiovanni Ceregioli, who leads iGuzzini’s research
centre, even suggests that we should start measuring
lighting efficiency in circadian light per watt – taking
into account not just the amount of lumens emitted by
a light, but whether or not they affect us positively by
promoting a healthy daily rhythm.
Although the science behind the technology is widely
accepted, it remains ‘hardly understood’, Frost says, and
there are still few real-world solutions that successfully
combine an understanding of the physiological effects
of light with efficiency and aesthetics.
An online information source, Lighting for People
(lightingforpeople.eu), backed by the European
Commission and Lighting Europe, has been set up to
bring together the latest research about human-centric
lighting. It is building up a body of knowledge about
biodynamic lighting and how it could be applied in our
offices, schools, cities, homes and hospitals, with the hope
of making us happier, healthier and more productive.
In workplaces, for instance, every employer wants
alert, energetic employees, and it seems that brighter,
more intense light in the workplace is the key. The
challenge is to provide stimulating and pleasant settings
that promote vitality and concentration, while taking
account of individual workers’ preferences.
Research suggests that exposure to more intense light
boosts employees’ feelings of alertness and vigour. At
the very least it can counteract feelings of tiredness,
although this may depend on the duration and timing
of the exposure. Scientists are not yet agreed on the best
intensity to create a wide awake workplace.
Light intensity can affect employees’ feelings about
their working environment. Studies have shown that
rooms lit by sources with a higher illuminance are
generally viewed as brighter. Spaces with high-intensity
lighting are regarded as more lively and less tense, and
most workers like higher intensity lighting at the work
surface. Very high-intensity electric lighting (above 93
foot-candles, 1000 lux), however, is off-putting to some.
Employers concerned about sleepy staff should note
that exposure to bright light ( 93 foot-candles, 1000 lux)
in the afternoon helps employees feel alert after a short
night’s sleep. Dim light (below 0.5 foot-candles, 5 lux),
on the other hand, increases sleepiness. In fact, research
shows that working under intense light during the day
may ensure a better night’s sleep.
The impact of bright lighting on employees’
productivity seems to depend on what they are doing.
Some studies have found that exposure to lighting levels
above 185 foot-candles (2000 lux) may enhance people’s
capacity for visual scanning, short-term memory and
mental arithmetic. However, a study that compared
the effects of working under 93 and 185 foot-candles
(common in offices) found no improvement in visual
scanning or the ability to concentrate. More research is
needed to establish optimum lighting levels for different
activities during the working day.