Definitions of heighten:

• verb:   make more extreme; raise in quantity, degree, or intensity

  Example: "Heightened interest"

• verb:   become more extreme

  Example: "The tension heightened"

• verb:   increase the height of

  Example: "The athletes kept jumping over the steadily heightened bars"

• verb:   increase

  Example: "Heighten the tension"

• verb:   make (one's senses) more acute
• verb:   make more intense, stronger, or more marked

  Example: "Potsmokers claim it heightens their awareness"