A good lesson not to ignore things, and for everyone to be aware that sudden changes in their colleagues behaviors are more likely serious issues of any sort than they are laziness or idiocy.

I was fortunate in college to discover fairly serious cancer very early (total accident), and am very appreciative of the support I received at the time. Likewise, someone very close to me who had been behaving oddly for a while was diagnosed with a serious nutritional deficiency that explained everything.

Bodies and minds are terribly imperfect, and if someone you know is suddenly behaving oddly, at best it's a serious personal problem, at worst it's a physical problem even they may not recognize. Be a friend to them!