According to Professor Alan Hedge, director of Cornell University’s Human Factors and Ergonomics Research Group, a person should be able to sit in an office chair for one to two hours without discomfort.

From his research into the effects on the human body of sitting for extended periods, he advises that a person should take frequent short breaks to relieve the stress on the spine, especially the lower back, and to relieve pressure on the thighs that can restrict blood flow.

It doesn’t require much research at all for anyone to realize that the more comfortable the chair, the longer will a person sit in it before he or she gets up to relieve discomfort. People engaged in intensive work will probably forget Prof. Hedge’s advice and omit some of the breaks, tending to sit for longer and interrupting work less.