For some people mental stress is a major trigger.Doesn't mean IBS is caused by stress, just stress triggers it to act up. IBS has a physical cause, but like most every disease stress tends to make it worse.Different people have different triggers.Physical stress (over-tired, over-worked, etc.) can be just as bad for some people as mental stress. For others it is diet, or the weather, or hormon fluxes, etc.If mental stress triggers your IBS then finding healthy ways to deal with stress may be a good approach for you.K.