Posted By Simon Wright Harsh, bright, piercing light can cause problems as it makes people unnecessarily tired and strain their eyes. Your body is subconciously in tune with natural light levels and artificial light can confuse and strain your eyes. I read a report a few years ago stating that if you were working in subdued light for a proportion of your day then it was actually good for your eyes as the muscles were being gently exercised and you were making them work which kept them working more effectively. I have always preferred to work in an office with more subdued lighting, to the point that I've taken fluorescent tubes out to lower the light levels around my desk. It never ceases to amaze me how many bespectacled co-workers comment about the subdued light levels which I work in to which I always respond "Er, which of us two needs to use glasses and which one is taking care of his eyes?". There will obviously be a minimum light level required in a large number of industries for safe working but there are problems with open plan offices where the offices are made as bright as possible while the workers underneath all have differing light level preferences but just get stuck with harsh lighting which leaves some of them exhausted by the end of the day.