Did you know the winter blues, aka Seasonal Affective Disorder, can be treated with light therapy? You’re probably aware that the blue light emitted by your phone and computer may be wreaking havoc with your sleep. But could light also be affecting your health and mood in other ways?
Let there be light
Danielle Feinberg, Pixar’s director of photography, argues that light is the magical ingredient that brings animated worlds to life. For example, without careful attention to lighting, WALL-E is just a metal robot, not a lovable personality with a soul. Yet light is such a fundamental part of our lives that we tend to take it for granted.
The sun rises and light floods our world. After sunset, we flick on a light switch anytime we want to. It’s easy to forget light has a profound effect on our brain, body rhythms and overall health. Light obviously allows us to see, but our eyes also have light-sensitive cells that have nothing to do with vision. Instead, they send information about light levels to our brain, controlling our 24-hour body clock, triggering us to be alert and playing a role in our short-term memory.
Exposing our bodies to irregular light cycles affects our mood and brain function. The most well-known example of this is Seasonal Affective Disorder (SAD), a pattern of repeated depression that occurs during autumn or winter in up to 9% of people. There is some evidence that exposure to bright light improves this form of depression although a study published earlier this year questioned the existence of SAD.
The dark side of light: red, white and blue
If you live in a city, one of the most obvious aspects of light is that it’s virtually impossible to escape. Research out this week – the atlas of artificial night sky brightness – brought the depressing news that more than 80% of the world lives under light-polluted skies. Gone are the days of navel-gazing under a starry sky – more than a third of people can no longer see the Milky Way because the night sky where they live is so artificially bright.
There has been plenty of research looking at the health effects of light pollution. Essentially, being exposed to light at night completely stuffs up our body clocks with flow-on effects such as depression, cancer, weight gain and learning difficulties. How? Being exposed to artificial light at night suppresses production of the hormone melatonin, which we need to regulate our natural body rhythms.
Of course, artificial lights come in different colours and chances are you’ve heard that the blue light streaming out of your smart phone, or tablet, or computer, is particularly bad for you at night. During the day, being exposed to blue light makes us alert, better able to pay attention and faster in our reaction times.
But at night, blue light is the most powerful at suppressing melatonin. In one study, people were asked to read either a printed book or e-book for five nights in a row. Those who read the e-book had a delay in melatonin release of more than an hour and a half, they took longer to fall asleep and were less alert in the morning. This research has led to the popularity of plenty of programs and apps that reduce our exposure to the blue light of our screens. White light is somewhat better and red light, the least disruptive at night.
If I say mood lighting, you probably think of dimly-lit lamps. And with good reason: there’s strong evidence that brightness of lighting affects our moods. Bright street lighting makes us feel safe and something as simple as having access to a window at work can result in better sleep and a better quality of life. At work, we feel happiest when our office lights are neither too bright nor too dim. Sunshine makes us feel optimistic and can even influence the stock exchange.
But there’s more to it than that. Under bright light, we feel warmer, regardless of temperature. And the more intense the lighting, the stronger our emotional response. Under bright lights, we judge attractive people to be more attractive, positive words to be more positive, and negative words to be more negative. In bright lights, we also choose the spiciest foods!
Ambient lighting also influences how calm we feel. It’s not surprising then that airlines are now investing in mood lighting for cabins: no more instantaneous changes from dark to bright lights on a long-haul flight when the aim is to calmly get breakfast into you before landing.
And mood lighting isn’t just for us: farmers have found mood lighting makes for ‘relaxed, happy chickens.’ That’s something to crow about!