Calea zacatechichi is a medium-sized shrub that is known to increase dreams. Because of this, it is often referred to as the "dream herb". It also is called "bitter grass" because the plant material has an intensely bitter taste. It has been used in folk remedies for thousands of years.Some people use Mexican Dream Herb to induce psychic dreams, to help remember dreams, and to increase dreaming. In addition, it has also been studied for mental enhancement and sleep.