The orbits of sungrazing comets originally have inclinations near 90° and perihelion distances in the approximate range 0-2 AU. Long-term secular perturbations cause correlated changes in the orbital elements, especially the perihelion distance, eccentricity and inclination, which eventually lead to a temporary sungrazing state of extremely small perihelion distance. At such a time the comet may suffer tidal disruption or destruction by solar heating.