Changing the view from a bright area to a dark area demands adaptation of the eyes.This takes time and is tiring.
It is more efficient and more comfortable to work in a room that does not have large variations in brightness.
It is important to suppress flickering light. Such lighting is annoying to everybody and causes eye fatigue. It even produces some odd effects dangerous to sufferers of epilepsy.
Sharp shadows on the work surface are a source of poor work quality low productivity, eye strain, fatigue and sometimes accidents. Eliminate shadows.