If you've ever gone to a retreat to renew your life and actually felt renewed, it may be because real changes have taken place in your brain. Researchers at Thomas Jefferson University found that spiritual, meditative, and religious retreats boost levels of dopamine and serotonin in the brain — the "feel good" chemicals.

Their study included Christian participants ranging in age from 24 to 76. They attended an Ignatian retreat based on the spiritual exercises developed by St. Ignatius Loyola who founded the Jesuits.

Following a morning mass, participants spent most of the day in silent contemplation, prayer, and reflection, and attended a daily meeting with a spiritual director for guidance and insights.

After returning from the retreat, study subjects also completed a number of surveys which showed marked improvements in their perceived physical health, tension and fatigue.

Scans conducted after the retreat found decreases in dopamine transporter binding (5 to 8 percent) and serotonin transporter binding (6.5 percent), which could make more of the neurotransmitters available to the brain.

These chemicals are associated with positive emotions and spiritual feelings. Dopamine is responsible for mediating cognition, emotion and movement, while serotonin is involved in emotional regulation and mood.

"Since serotonin and dopamine are part of the reward and emotional systems of the brain, it helps us understand why these practices result in powerful, positive emotional experiences," said Andrew Newberg, M.D. "Our study showed significant changes in dopamine and serotonin transporters after the seven-day retreat, which could help prime participants for the spiritual experiences that they reported."

Study results were published in Religion, Brain & Behavior.

Other studies have found that meditation and reflection offer many health benefits. Scientists at Seattle's Group Health Research Institute found that meditation may work better than drugs to ease chronic low back pain. Eight weekly sessions of mindfulness-based stress reduction (MBSR), such as meditation, relieved pain and improved ease of movement better than conventional care, such as over-the-counter pain killers.

Meditation has also been used to counteract loneliness in the elderly, which increases the risk of depression, heart disease, and Alzheimer's. UCLA researchers found that meditation altered the genes and protein markers for inflammation — a major player in many diseases of aging.