At least in vipassana, the dark night period is considered to be a phase along the path or whatever. In other words, you basically can't reach enlightenment without having a complete mental breakdown and losing your ability to hold down a job and function normally in society, often for a couple years if not permanently. C.f. her interviews on the Buddhist Geeks.

You're not going to have issues if you're just meditating for fifteen or twenty minutes a day or whatever, it's only if you're doing this for hours every day and getting into the ego dissolution stages.