Soul n Peace

Many authorities avoid emphasizing the effects of meditation — sometimes out of modesty, sometimes for fear that the expectation of results might interfere with one's meditation. For theists, the effects of meditation are considered a gift of God or from the Holy Spirit/Ghost, and not something that is "achieved" by the meditator alone, just as some say that a person will not convert to Christianity without the influence of the Holy Spirit/Ghost's presence.   

At the same time, many effects (or perhaps side-effects) have been experienced during, or claimed for, various types of meditation. These include:   

Greater faith in, or understanding of, one's religion or beliefs  

An increase in patience, compassion, and other virtues and morals or the understanding of them  

Feelings of calm or peace, and/or moments of great joy

Consciousness of sin, temptation, and remorse, and a spirit of contrition.  

Sensitivity to certain forms of lighting, such as fluorescent lights or computer screens, and sometimes heightened sense-perception.

Surfacing of buried memories.

Experience of spiritual phenomena such as kundalini, extra-sensory perception, or visions of deities, saints, demons, etc.

"Miraculous" abilities such as levitation (cf. yogic flying)

Psychotic episodes (see medical section below)

Some traditions acknowledge that many types of experiences and effects are possible, but instruct the meditator to keep in mind the spiritual purpose of the meditation, and not be distracted by lesser concerns. For example, Mahayana Buddhists are urged to meditate for the sake of "full and perfect enlightenment for all sentient beings" (the bodhisattva vow). Some, as in certain sects of Christianity, say that these things are possible, but are only to be supported if they are to the glory of God.