Is dim indoor lighting making us dimmer?
How much time do you spend outside each day? Research suggests it’s probably not very much, with statistics showing that we spend about 90 per cent of our days indoors.
The indoor environment that we are exposed to can have a huge impact on our productivity and new research suggests that spending too much time in dimly-lit rooms could change the way our brains process information.
The positive effects on our cognitive function of immersing ourselves in bright ambient light are well known.
A study published this week in the journal Hippocampus looked into this further by studying how different light conditions affected the brain over a longer time period.
The study used rats because, like humans, rats are diurnal, meaning that they are most active in the day and sleep at night.
The rats were split into two groups, one group was housed under dimly-lit conditions and the other group in brightly-lit conditions.
After four weeks of receiving 12 hours of their selected light then 12 hours of dark per day, the mental skills of the rats were put to the test.
Using a Morris Water Maze, which involves placing the rats in a large circular pool and monitoring how well they find a platform to escape, the rats were compared with each other.
The results showed that the rats which had been kept under dimly-lit conditions performed poorly in the test and showed impaired spatial memory as well as a reduction of brain-derived neurotrophic factor (BDNF).
BDNF is known to support the survival of existing neurons, and encourage the growth of new neurons, implying that low-light conditions can result in fewer neural connections being made in the brain.
Overall the dimly-lit rats lost about 30 per cent of the capacity in a part of their brain called the hippocampus, which was thought to be responsible for their reduced learning and memory performance.
The good news was that the negative effects seen from the lowlighting conditions seemed to be reversible as the poor performing rats produced much better results after they were housed in brighter living Dr Michelle Dickinson, also known as Nanogirl, is an Auckland University nanotechnologist who is passionate about getting Kiwis hooked on science. Tweet her your science questions @medickinson
conditions for a further four weeks.
This study supports other research that has shown how important light is for our circadian rhythm or natural body clock which helps us to fall asleep at night-time and be active during the day.
Further understanding of these rhythms using different light sources could potentially help us to design offices that encourage people to be more productive at work by using different light sources at different times of the day.
Several studies have shown that when humans are exposed to blue light — the main colour we see when we are outdoors, our bodies suppress the amount of melatonin we release.
Melatonin is the brain chemical that can help us to feel sleepy, so less melatonin keeps us awake and alert.
Bright blue based lights are thus ideal for peak employee performance in the office during the day.
The same principle can also keep us up at night which is why taking bright blue screened laptops or smartphones to bed is never a good idea if you want to fall asleep quickly.
Warm red lights have been shown to help promote our natural sleep cycles and ideally, our bedrooms should immerse us in a dimly-lit red glow to increase our melatonin production to help us nod off.
As our love of indoor lifestyles doesn’t look like it will be changing anytime soon, and the next generation rush home to play video games rather than play outside, our power to learn might actually be held in the powerful colour of a lightbulb.