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Light and the body clock: the key to a good night’s sleep?
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. One study suggested that after 17-19 hours of staying awake, performance on cognitive tasks may be similar to having had too much to drink.
These effects worsen over time. But while scientists have long understood the importance of getting enough sleep, the key part played by light exposure can sometimes be overlooked. The reason light is so important is that it sets our 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 rhythm so that the internal and external day coincide. This is so powerful that people who have very severe eye damage can find their body clock is thrown off, leading to sleep problems.
Today, many of us miss out on these environmental cues as we work inside. We have become a light deprived species, and this has far reaching consequences for the quality of our sleep, and consequently our wellbeing.
Further research and greater awareness ∈ this area could help individuals to make informed choices about prioritising their own sleep and getting enough sunlight. It could also influence the way that policies are developed by governments, educational institutions and workplaces. Minimising light exposure before you go to bed, and trying to get as much morning light as possible, are simple steps that could help most people to regulate and improve their sleep.
(Russell Foster. www.bbc.com, 19.05.2019. Adaptado.)
According to the text, the cycle of sleep and wakefulness is essential for human beings because
