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Light sets the time on our circadian clock. When our biological and behavioural rhythms are out of alignment, our systems are more prone to malfunction.
For instance, our body doesn’t process food as well late at night, when our body is trying to wind down.
“So you’ll tend to gain weight more and have probably more difficulty in processing glucose and whatnot at night,” Cain explains.
He adds that the pancreas, gut and liver are all rhythmic as well, operating differently depending on the time of day. “When you disrupt the clocks with low daytime light and high nighttime light, it’s going to lead to more disruptions in this tissue’s ability to do its job at the right time.”
The result is a greater propensity towards illness. “Poor light patterns will tend to make you more vulnerable to whatever chronic disease you might tend toward.”
Lighting up our lives, at the right times of day, is vitally important.Credit: Getty Images/iStockphoto
This is particularly problematic for Australia’s 1.4 million shift workers.
“Unfortunately, there’s no magic bullet here,” Cain admits. “We are day-active, night-sleeping animals, and when we don’t do that, we’re acting against our physiology.”
Though people in certain professions may not be able to choose when they are and are not exposed to light, Marshall agrees that, in the long term, poor light patterns can negatively affect health.
And though blue light is perceived differently in our brain and may suppress melatonin, Marshall says this research suggests the intensity of the light is more important than the hue.
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Interestingly, chronotype (our inclination to sleep and wake at certain times) does little to influence the effect of bright light at night.
Previous research has found that when electric lights are removed at night (while camping, for instance), night owls tend to adopt similar sleep and wake behaviours to those who consider themselves early birds.
“The power of your chronotype really is more of a modern phenomenon that is a result of exposure to artificial light,” says Cain, who has developed a wearable light sensor which will soon become available to the public.
In the future, he anticipates that we will become more cognisant of the health effects of bright lights at night and switch to smart lights, which automatically dim and emit a more orange light.
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The good news is that our bodies are highly responsive to changes in light.
When we start exposing ourselves to healthier light patterns – bright, natural light upon waking and throughout the day (natural daylight is far more intense than artificial office lights), dimmer lights as the sun goes down and near total darkness for sleeping – the strength of our clocks are boosted quickly.
“They’re better able to influence and control all of your physiology essentially,” Cain says. “Your clock can better organise all of your body to be doing the right things at the right time.”
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