Among the conditions for one’s fasting to be valid is that the person does not become insane, not even for a moment, during the fasting day. If a person loses his sanity during the day or during part of the day, even for a moment, then his fasting will be invalidated. In addition to this, one’s fasting is invalid if one loses consciousness during the entire fasting day, that is, from the dawn until sunset. However, if one loses consciousness for only part of the day, this does not invalidate the fast. On the other hand, sleeping does not invalidate the fast, even if one slept all day long.