While scientists have long understood the importance of getting enough sleep, the key part played by light exposure can sometimes be overlooked, reports BBC News.
Without any access to light, the human body clock appears to drift, adding about half an hour on to its 24 hour cycle for each day of darkness. Jetlag is the most obvious example of the effect light can have. Exposure to light in the new time zone helps reset our body clock to local time, telling us the right time to sleep.
In 1800, most people across the world worked outside and were exposed to the change from day to night. Today, many of us miss out on these environmental cues as we work inside. Agriculture and fishing, for example, now make up just 1% of jobs in the UK.
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.