The cycle of sleep and wakefulness is one of the key human behaviours.
We spend about a third of our lives asleep and cannot survive without it.
When asleep, our brain memorises and processes information. Our body clears toxins and repairs itself, allowing us to function properly when awake.
Even short-term sleep deprivation significantly affects our wellbeing. Most of us begin to fall apart after just one night without sleep and after three nights of missed sleep, we are functioning way below par.
These effects worsen over time. Thelongest documented period without sleepof just more than 11 days prompted serious cognitive and behavioural changes, problems with concentration and short term memory, paranoia and hallucinations.
But while scientists have long understood the importance of getting enough sleep, the key part played by light exposure can sometimes be overlooked.
Setting the body clock
The reason light is so important is that it sets our circadian rhythm, or body clock, via specialised light sensors within the eye.
Our eye detects the light and dark cycle within our environment and adjusts the body’s circadian rhythm so that the internal and external day coincide.
We have become a light deprived species, and this has far reaching consequences for the quality of our sleep, and consequently our wellbeing. The optimum amount varies from person to person, but we do know that our bodies need exposure to very bright light that the majority of indoor lighting does not provide.
And there are many other areas where lack of natural light has caused problems.
Working the nightshift
While many of us aren’t getting enough natural light, for nightshift workers it is a particular issue.
They have to work at a time when the body clock has prepared the body for sleep, and alertness and performance ability are low. They may try to make up on sleep during the day, but it will usually be shorter and of poorer quality.
In effect, they work when they are sleepy and sleep when they are not, and the negative health effects of this are only just being fully realised.
In the short term, it can prompt abnormal emotional responses and an inability to process information correctly.